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Arthroscopic Treatment of Anterior Ankle Impingement: A Prospective Study of 46 Patients With 5-Year Follow-up Stewart J. Walsh, Bruce C. Twaddle, Michael P. Rosenfeldt and Matthew J. Boyle Am J Sports Med 2014 42: 2722 originally published online September 26, 2014 DOI: 10.1177/0363546514550976 The online version of this article can be found at: http://ajs.sagepub.com/content/42/11/2722
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Arthroscopic Treatment of Anterior Ankle Impingement A Prospective Study of 46 Patients With 5-Year Follow-up Stewart J. Walsh,* FRACS, Bruce C. Twaddle,*y FRACS, Michael P. Rosenfeldt,* FRACS, and Matthew J. Boyle,*z FRACS Investigation performed at Unisports Sports Medicine, Auckland, New Zealand Background: Midterm outcomes after arthroscopic debridement in patients with anterior ankle impingement without osteoarthritis are currently unclear. Purpose: To assess the functional and radiological outcomes after arthroscopic treatment of anterior ankle impingement with a minimum 5-year follow-up in patients without osteoarthritis. Study Design: Case series; Level of evidence, 4. Methods: From September 1999 to March 2006, a consecutive series of eligible patients without ankle osteoarthritis and with anterior ankle impingement, who had persistent ankle pain and activity restrictions despite at least 6 months of nonoperative management, underwent standardized arthroscopic debridement and followed uniform postoperative management. Patients were assessed preoperatively and at 6 weeks, 6 months, and 12 months and then at 1-year intervals after surgery until a minimum of 5 years’ follow-up had been achieved, with weightbearing ankle dorsiflexion, Foot Functional Index (FFI), and plain radiography including Scranton and McDermott classification (SMC) grade and tibial osteophyte size. Results: A total of 46 patients (42 male, 4 female) were prospectively assessed, with a mean age at surgery of 29 years (range, 16-44 years) and a mean follow-up duration of 5.1 years (range, 5.0-7.5 years). Preoperative ankle radiographs demonstrated a median SMC grade of 2 and a mean tibial osteophyte size of 5.1 mm. At a minimum of 5 years postoperatively, patients demonstrated limited improvement in ankle dorsiflexion (mean, 24.7° [preoperatively] vs 27.0° [final follow-up]; P = .049); however, they demonstrated substantial improvement in the FFI (mean, 20.5 [preoperatively] vs 2.7 [final follow-up]; P \ .001). Postoperatively, 84% of patients showed a recurrence of radiological osteophytes, with plain radiographs at final follow-up demonstrating no significant difference in the SMC grade (P = .107) or tibial osteophyte size (P = .212) compared with preoperative imaging. There was no significant effect of patient age, sex, body mass index, or SMC grade at the time of surgery on any of the postoperative outcome measures. Conclusion: In this prospective outcome study of 46 patients without osteoarthritis managed arthroscopically for anterior ankle impingement, the functional outcome scores had significantly improved at 5 years postoperatively despite a recurrence of radiographic osteophytes. Keywords: ankle impingement; ankle arthroscopic surgery; functional outcomes; athletes
1943 by Morris,14 ankle impingement is a common cause of ankle pain in athletic patients and is frequently associated with sporting activities involving repetitive forced dorsiflexion or plantar flexion of the ankle. The exact cause of this condition is debated but seems to involve osteophyte formation due to either repetitive microtrauma or macrotrauma associated with major injuries.4,9,18,20 Recently, the concept of cam-type impingement in the ankle has also been proposed,1 with certain anatomic features possibly resulting in altered ankle joint mechanics and impingement. Once anterior ankle impingement is established, repetitive impaction of the impinging tissue results in pain, restricted ankle motion, functional disability, and often traumatic chronic synovitis that may be resistant to nonoperative measures.10
Anterior ankle impingement is characterized by anterior ankle pain with restricted and painful dorsiflexion due to soft tissue11 or bony15 impingement. First described in
z Address correspondence to Matthew J. Boyle, FRACS, Unisports Sports Medicine, 71 Merton Road, PO Box 18067, Glenn Innes, Auckland 1743, New Zealand (e-mail: [email protected]). *Unisports Sports Medicine, Auckland, New Zealand. y Sports Medicine Center at Husky Stadium, Seattle, Washington, USA. The authors declared that they have no conflicts of interest in the authorship and publication of this contribution.
The American Journal of Sports Medicine, Vol. 42, No. 11 DOI: 10.1177/0363546514550976 Ó 2014 The Author(s)
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Vol. 42, No. 11, 2014
Arthroscopic Treatment of Ankle Impingement
The treatment of patients with anterior ankle impingement who fail nonoperative management typically involves arthroscopic or open surgical debridement of the impinging osteophytes and soft tissue. While successful open treatment of anterior ankle impingement has been reported,8,17 arthroscopic treatment of this condition has become increasingly popular2,4,5,13,17,19,22,23 because of the benefits of reduced recovery time and earlier return to sports compared with open debridement.17 Promising short-term arthroscopic results have been reported2,4,5,13,17,19,23; however, only 1 midterm study has been presented to date.22 Furthermore, many previous studies have included mixed diagnoses, including large numbers of patients with osteoarthritis.5,22,23 It therefore remains unclear as to the expected midterm outcomes of patients without arthritis and whether osteophytes in such patients recur over time. The aims of this prospective study were to determine the minimum 5-year clinical, functional, and radiological outcomes after arthroscopic treatment of anterior ankle impingement.
MATERIALS AND METHODS After ethical review board approval, a consecutive series of patients with anterior ankle impingement seen at our institution from September 1999 to March 2006, who had persistent ankle pain and associated activity restrictions despite at least 6 months of nonoperative management (rest, nonsteroidal anti-inflammatory medication, physical therapy, ankle bracing, shoe modification) and were scheduled for arthroscopic surgery, were assessed for study inclusion. Weightbearing plain radiography and magnetic resonance imaging (MRI) of the affected ankle were performed preoperatively. Patients with osteochondral talar dome lesions, talar dome fractures, or avascular necrosis of the talus on MRI; joint space narrowing of the tibiotalar, subtalar, or midtarsal joints on plain radiography; worse than Outerbridge16 grade I changes to either the distal tibial or talar dome articular cartilage on arthroscopic examination; tibiotalar instability on examination under anesthetics; or a history of ankle fractures were excluded from the study. All patients prospectively gave informed consent to participate in the study. All included study patients had single-leg weightbearing ankle dorsiflexion clinically measured, the Foot Functional Index (FFI) completed,7 and exercise activity levels assessed preoperatively by an independent orthopaedic sports medicine clinician (not involved in patient care), and preoperative weightbearing anteroposterior and lateral plain ankle radiographs undertaken by an experienced musculoskeletal radiographer were recorded. With respect to the exercise activity level, all patients were asked to quantify the number of exercise sessions undertaken in the week immediately before assessment (0, 1-2, 3-4, or 5 sessions) and the mean duration of exercise sessions during that week (\30, 30-60, 60-90, 90-120, or .120 minutes). Although not validated, these 2 exercise activity questions were selected as a simple measure to broadly compare patient activity preoperatively and postoperatively. Preoperative
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and postoperative plain radiography was not standardized for the purposes of this study but rather was undertaken to include anteroposterior and lateral radiographs of the tibiotalar joint according to standard local radiography protocols for the assessment of ankle pain. Preoperative radiographs were assessed for Scranton and McDermott classification (SMC)17 grade and tibial osteophyte size by an orthopaedic sports medicine fellow who was blinded to patient outcomes. All study patients underwent standardized outpatient surgery, with arthroscopic debridement of impinging bony and soft tissue performed by 1 of the 2 senior authors (S.J.W. and B.C.T.) utilizing standard anterolateral and anteromedial arthroscopic portals without the use of intraoperative radiographic imaging. All patients followed a uniform postoperative management program, with immobilization for the first postoperative week and partial weightbearing in a walking boot for 2 weeks. Once the portals healed, a nonimpacting cycling, stretching, and waterbased rehabilitation program was commenced. Patients returned to running no sooner than 4 weeks after surgery. Postoperatively, patients were assessed by an independent orthopaedic surgeon at 6 weeks, 6 months, and 12 months and then at 1-year intervals after surgery until a minimum of 5 years’ follow-up had been achieved. Single-leg weightbearing ankle dorsiflexion, FFI, exercise activity level (number of exercise sessions undertaken in the week immediately before assessment and the mean duration of exercise sessions during that week), and plain radiographs were recorded at each time point. Final postoperative radiographic analysis was undertaken by an independent orthopaedic sports medicine fellow who was blinded to patient outcomes but was not blinded to the follow-up time. Final data analysis was undertaken by an independent orthopaedic sports medicine fellow.
Methodological Considerations The FFI is a validated, self-reported instrument for the assessment of multiple dimensions of foot function based on patient-centered values. It consists of 23 items divided into 3 subscales that quantify the effect of foot pathological disorders on patients’ pain, disability, and activity limitation, with a lower score indicating superior function.7 The FFI has been found to have good reliability and validity.6,7,12 The SMC17 grade is a widely used classification system that categorizes anterior ankle impingement into 4 grades according to lateral ankle plain radiography: grade 1 when a tibial osteophyte is \3 mm, grade 2 when the osteophyte is .3 mm, grade 3 when there are both tibial and talar osteophytes, and grade 4 when there is associated joint space narrowing.
Statistical Analysis Comparisons of preoperative and postoperative scores were made using paired t tests. The associations between baseline measures and postoperative scores were tested using independent t tests for patient sex and Pearson
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TABLE 1 Results of Arthroscopic Treatment of Anterior Ankle Impingement at Minimum 5-Year Follow-up (N = 46 Patients)a Variable
Preoperative
Final Follow-up
Ankle dorsiflexion, deg FFI score Pain subscale Difficulty subscale Activity subscale SMC grade, median 6 SD Tibial osteophyte size, mm
24.7 20.5 25.0 21.6 13.3 2.0 5.1
27.0 2.7 3.1 3.1 1.2 2.0 4.3
6 6 6 6 6 6 6
6.3 17.6 21.0 22.7 15.5 0.7 2.7
6 6 6 6 6 6 6
7.5 4.8 5.2 6.9 3.4 0.9 3.1
P Value .049 \.001 \.001 \.001 \.001 .107 .212
a Values are reported as mean 6 SD unless otherwise indicated. FFI, Foot Function Index; SMC, Scranton and McDermott classification.
correlation coefficients for continuous baseline variables. A 2-tailed P value of \.05 was taken to indicate statistical significance.
RESULTS We enrolled 50 eligible patients during the study period. Of these patients, 3 were lost to follow-up, and 1 died before study completion, leaving 46 patients available for clinical, functional, and plain radiographic assessments with a minimum 5-year follow-up.
Baseline Information At the time of surgery, there were 42 male and 4 female patients, with a mean age of 29 years (range, 16-44 years) and a mean body mass index (BMI) of 26.7 kg/m2 (range, 19.8-36.0 kg/m2). All patients participated in competitive sports preoperatively, with the primary sport being rugby in 17 patients (37.0%), soccer in 10 patients (21.7%), rugby league in 2 patients (4.4%), tennis in 2 patients (4.4%), and other in 15 patients (32.6%); 40 patients participated in local or regional club-level sports, and 6 patients participated in professional or international competitions. Preoperatively, the mean ankle dorsiflexion was 24.7°, and the mean FFI was 20.5 (Table 1). Preoperative ankle radiographs demonstrated a median SMC grade of 2 (range, 1-3) and a mean tibial osteophyte size of 5.1 mm (range, 1-10 mm).
Postoperative Outcomes The mean follow-up duration was 5.1 years (range, 5.0-7.5 years). The postoperative clinical examination demonstrated improvement in the mean ankle dorsiflexion to 28° at 1-year follow-up (P \ .001) and 27° at final followup (P = .049) (Table 1). The functional assessment demonstrated substantial postoperative improvement in the mean FFI to 3.8 at 1-year follow-up (P \ .001) and 2.7 at final follow-up (P \ .001). Every FFI subscale also
Figure 1. Weightbearing lateral radiographs of the ankle in terminal dorsiflexion of a 26-year-old male patient. (A) Preoperative radiograph, demonstrating anterior ankle impingement with a prominent tibial osteophyte (Scranton and McDermott classification grade 2). (B) Radiograph taken 6 weeks after arthroscopic treatment, demonstrating satisfactory removal of an anterior tibial osteophyte. (C) Radiograph taken 5 years after arthroscopic treatment, demonstrating the recurrence of an anterior tibial osteophyte. (D) Weightbearing anteroposterior radiograph of the ankle 5 years after arthroscopic treatment, demonstrating no significant osteoarthritic change. The 5-year functional scores for this patient were excellent.
improved significantly after surgery (all P \ .001). There was no significant change in the exercise activity level between the preoperative and 1-year status (P = .185) or between the preoperative and final postoperative status (P = .147). Compared with preoperatively, 22 patients increased, 19 patients decreased, and 5 patients showed no change in exercise frequency or duration at 1-year follow-up, and 21 patients increased, 21 patients decreased, and 4 patients showed no change in exercise frequency or duration at final follow-up. Plain radiography at 6 weeks postoperatively demonstrated complete osteophyte resection in all patients. At final follow-up, osteophytes typically had recurred (Figure 1), with plain radiographs demonstrating no significant difference in the SMC grade (median, grade 2 [preoperative and final follow-up]; P = .107) or tibial osteophyte size (mean, 5.1 mm [preoperative] vs 4.3 mm [final follow-up]; P = .212) compared with preoperative imaging (Table 1). Correlation analyses demonstrated significant positive associations between the preoperative ankle dorsiflexion and postoperative ankle dorsiflexion (r = 0.41, P = .005) and between the preoperative tibial osteophyte size and postoperative SMC grade (r = 0.41, P = .029). There were
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Arthroscopic Treatment of Ankle Impingement
no significant effects of baseline patient age, sex, BMI, or SMC grade on any of the postoperative outcome measures.
DISCUSSION Good short-term outcomes after arthroscopic treatment of anterior ankle impingement have been reported2,4,5,13,17,19,23; however, midterm studies are limited. Our results compare favorably with those of the only other midterm study published to date, which was a series of 57 patients, with a mean age of 36 years, who were assessed at a minimum of 5 years after arthroscopic management of anterior ankle impingement.22 At a mean follow-up of 6.5 years, the overall patient satisfaction score in that study by Tol et al22 was 74%, and the overall successful treatment score was 65% (based on the lowest score for pain, swelling, stiffness, limping, or activity), with better results seen in patients without preoperative joint space narrowing. In the present study, we excluded patients with preoperative degenerative joint disease. In our study, we have presented clinical examination results, in addition to radiological and functional outcomes, at a minimum of 5 years after arthroscopic management of anterior ankle impingement. Our clinical results are interesting in that although we observed a statistically significant improvement in ankle dorsiflexion after surgery, this improvement was small and of questionable clinical significance. It is difficult to know why there is a limited improvement in ankle dorsiflexion after surgery both at early and midterm follow-ups. We hypothesize that posterior tibiotalar capsular contraction develops preoperatively in these patients, which restricts postoperative ankle dorsiflexion despite the removal of impinging bony and soft tissue anteriorly. Anterior osteophytes typically recur postoperatively, which may also contribute to the minimal postoperative improvement in ankle motion seen at midterm follow-up. Furthermore, the patients in our series did not have dramatically reduced ankle dorsiflexion preoperatively,3 which may have reduced the potential for substantial improvements postoperatively. In any case, it is important for patients to be advised that although improvements in ankle dorsiflexion after surgery may be limited, anterior ankle pain with dorsiflexion is reliably improved. Previous studies have recorded satisfactory early functional results after arthroscopic anterior ankle impingement surgery2,4,5,17,19,23; however, it is unclear whether these good results persist with time. The patients in our study displayed significant functional improvement at 1 year postoperatively, and importantly, this improvement was maintained at a minimum of 5 years postoperatively across all FFI subscales. This midterm persistence of satisfactory postoperative function was also observed in the midterm study of Tol et al22 and strongly supports arthroscopic treatment as a successful surgical option in patients with anterior ankle impingement. We also found that after surgery, our patients were able to return to at least the same level of exercise that they undertook preoperatively, which is an important finding in this young, athletic
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population. It is important to note that while we did not detect a significant improvement in exercise frequency or duration after surgery, this is likely a reflection on the shortcomings of the coarse measure of exercise activity levels that we employed; the postoperative improvements in the FFI suggest that our patient group experienced a positive, durable response to surgery. It is interesting to note that while postoperative function remained excellent, osteophytes typically recurred in our patients, with no significant difference in the median SMC grade between preoperative and final follow-up imaging. This postoperative recurrence of osteophytes, with the maintenance of good functional results, has been observed by previous authors.9,22 It is generally accepted that the recurrent osteophytes themselves are not painful in these patients.22 During terminal dorsiflexion, hypertrophic synovium and scar tissue become compressed between the anterior osteophytes, causing pain and swelling. The arthroscopic removal of osteophytes along with synovectomy and the removal of painful impinging soft tissue allow the pathoanatomy to be reversed. While we did not undertake repeat arthroscopic surgery, our positive functional results suggest that although the osteophytes recur, the painful hypertrophic synovium and scar tissue do not. It is important to note that despite the recurrence of osteophytes at midterm follow-up, the functional results in our patients remained excellent. This information is essential to convey to patients preoperatively, before treatment, so that they are adequately informed. Our study has a number of limitations. First, preoperative and postoperative plain radiography was not standardized, which may produce inaccuracies in the interpretation of radiographic results. Although arthroscopic assessment indicated the complete removal of anterior osteophytes, the lack of radiographic standardization and possible variability within the technique of lateral projection raise the possibility that early postoperative radiographs failed to demonstrate residual osteophytes. In addition, the radiographs were interpreted by an orthopaedic sports medicine fellow who was not blinded to the follow-up time, which introduces the possibility of confirmation bias. Furthermore, previous authors21 have indicated that oblique ankle radiographs, in addition to standard ankle radiography, may increase the diagnostic sensitivity in patients with suspected anterior ankle impingement. We believe that subtle radiographic differences have questionable clinical relevance, however, and the SMC grade remains a relatively broad, clinically relevant classification system. Therefore, our radiographic interpretation likely remains valid. Second, only 1 functional assessment tool was employed. The FFI is a validated scoring system that has been widely employed to assess the outcomes of ankle surgery,6,7,12 with the patient-centered, self-reported nature of the FFI likely providing a very relevant indication of patient outcomes. Third, we did not use a validated measure of patient exercise activity levels but rather assessed exercise activity using 2 simple, reproducible questions that we believe can be used to broadly compare patient activity
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preoperatively and postoperatively. Finally, we only achieved a minimum of 5 years’ follow-up; further followup is desirable to confirm the long-term persistence of our positive midterm patient outcomes. In this prospective outcome study of 46 patients without degenerative ankle arthritis managed arthroscopically for anterior ankle impingement, we found patient function to be significantly improved at 1 year after surgery, with maintenance of this improvement at a minimum of 5 years postoperatively. Patients managed arthroscopically for anterior ankle impingement can be advised that although radiographic osteophytes may recur, excellent midterm functional outcomes are expected.
ACKNOWLEDGMENT The authors sincerely thank Associate Professor Christopher Frampton for his statistical assistance and Dr Annunziato Amendola for his kind review.
REFERENCES 1. Amendola N, Drew N, Vaseenon T, Femino J, Tochigi Y, Phisitkul P. Cam-type impingement in the ankle. Iowa Orthop J. 2012;32:1-8. 2. Arnold H. Posttraumatic impingement syndrome of the ankle: indication and results of arthroscopic therapy. Foot Ankle Surg. 2011; 17(2):85-88. 3. Baggett BD, Young G. Ankle dorsiflexion: establishment of a normal range. J Am Podiatr Med Assoc. 1993;83(5):251-254. 4. Baums MH, Kahl E, Schultz W, Klinger HM. Clinical outcome of the arthroscopic management of sports-related ‘‘anterior ankle pain’’: a prospective study. Knee Surg Sports Traumatol Arthrosc. 2006; 14(5):482-486. 5. Branca A, Di Palma L, Bucca C, Visconti CS, Di Mille M. Arthroscopic treatment of anterior ankle impingement. Foot Ankle Int. 1997; 18(7):418-423. 6. Budiman-Mak E, Conrad KJ, Mazza J, Stuck RM. A review of the foot function index and the foot function index-revised. J Foot Ankle Res. 2013;6(1):5.
7. Budiman-Mak E, Conrad KJ, Roach KE. The Foot Function Index: a measure of foot pain and disability. J Clin Epidemiol. 1991; 44(6):561-570. 8. Coull R, Raffiq T, James LE, Stephens MM. Open treatment of anterior impingement of the ankle. J Bone Joint Surg Br. 2003;85(4):550553. 9. Hayeri MR, Trudell DJ, Resnick D. Anterior ankle impingement and talar bony outgrowths: osteophyte or enthesophyte? Paleopathologic and cadaveric study with imaging correlation. AJR Am J Roentgenol. 2009;193(4):W334-W338. 10. Kim SH, Ha KI. Arthroscopic treatment for impingement of the anterolateral soft tissues of the ankle. J Bone Joint Surg Br. 2000;82(7):1019-1021. 11. Lahm A, Erggelet C, Reichelt A. Ankle joint arthroscopy for meniscoid lesions in athletes. Arthroscopy. 1998;14(6):572-575. 12. Landorf KB, Keenan AM. An evaluation of two foot-specific, healthrelated quality-of-life measuring instruments. Foot Ankle Int. 2002;23(6):538-546. 13. Liu SH, Raskin A, Osti L, Baker C, Jacobson K, Finerman G. Arthroscopic treatment of anterolateral ankle impingement. Arthroscopy. 1994;10(2):215-218. 14. Morris LH. Athlete’s ankle. J Bone Joint Surg Am. 1943;25:220. 15. O’Donoghue DH. Impingement exostoses of the talus and tibia. J Bone Joint Surg Am. 1957;39(4):835-852. 16. Outerbridge RE. The aetiology of chondromalacia patellae. J Bone Joint Surg Br. 1961;43:752-757. 17. Scranton PE Jr, McDermott JE. Anterior tibiotalar spurs: a comparison of open versus arthroscopic debridement. Foot Ankle. 1992; 13(3):125-129. 18. Tol JL, Slim E, van Soest AJ, van Dijk CN. The relationship of the kicking action in soccer and anterior ankle impingement syndrome: a biomechanical analysis. Am J Sports Med. 2002;30(1):45-50. 19. Tol JL, van Dijk CN. Anterior ankle impingement. Foot Ankle Clin. 2006;11(2):297-310, vi. 20. Tol JL, van Dijk CN. Etiology of the anterior ankle impingement syndrome: a descriptive anatomical study. Foot Ankle Int. 2004; 25(6):382-386. 21. Tol JL, Verhagen RA, Krips R, et al. The anterior ankle impingement syndrome: diagnostic value of oblique radiographs. Foot Ankle Int. 2004;25(2):63-68. 22. Tol JL, Verheyen CP, van Dijk CN. Arthroscopic treatment of anterior impingement in the ankle. J Bone Joint Surg Br. 2001;83(1):9-13. 23. van Dijk CN, Tol JL, Verheyen CC. A prospective study of prognostic factors concerning the outcome of arthroscopic surgery for anterior ankle impingement. Am J Sports Med. 1997;25(6):737-745.
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Arthroscopic Treatment of Anterior Ankle Impingement: A Prospective Study of 46 Patients With 5-Year Follow-up Stewart J. Walsh, Bruce C. Twaddle, Michael P. Rosenfeldt and Matthew J. Boyle Am J Sports Med 2014 42: 2722 originally published online September 26, 2014 DOI: 10.1177/0363546514550976 The online version of this article can be found at: http://ajs.sagepub.com/content/42/11/2722
Published by: http://www.sagepublications.com
On behalf of: American Orthopaedic Society for Sports Medicine
Additional services and information for The American Journal of Sports Medicine can be found at: Email Alerts: http://ajs.sagepub.com/cgi/alerts Subscriptions: http://ajs.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav
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Arthroscopic Treatment of Anterior Ankle Impingement A Prospective Study of 46 Patients With 5-Year Follow-up Stewart J. Walsh,* FRACS, Bruce C. Twaddle,*y FRACS, Michael P. Rosenfeldt,* FRACS, and Matthew J. Boyle,*z FRACS Investigation performed at Unisports Sports Medicine, Auckland, New Zealand Background: Midterm outcomes after arthroscopic debridement in patients with anterior ankle impingement without osteoarthritis are currently unclear. Purpose: To assess the functional and radiological outcomes after arthroscopic treatment of anterior ankle impingement with a minimum 5-year follow-up in patients without osteoarthritis. Study Design: Case series; Level of evidence, 4. Methods: From September 1999 to March 2006, a consecutive series of eligible patients without ankle osteoarthritis and with anterior ankle impingement, who had persistent ankle pain and activity restrictions despite at least 6 months of nonoperative management, underwent standardized arthroscopic debridement and followed uniform postoperative management. Patients were assessed preoperatively and at 6 weeks, 6 months, and 12 months and then at 1-year intervals after surgery until a minimum of 5 years’ follow-up had been achieved, with weightbearing ankle dorsiflexion, Foot Functional Index (FFI), and plain radiography including Scranton and McDermott classification (SMC) grade and tibial osteophyte size. Results: A total of 46 patients (42 male, 4 female) were prospectively assessed, with a mean age at surgery of 29 years (range, 16-44 years) and a mean follow-up duration of 5.1 years (range, 5.0-7.5 years). Preoperative ankle radiographs demonstrated a median SMC grade of 2 and a mean tibial osteophyte size of 5.1 mm. At a minimum of 5 years postoperatively, patients demonstrated limited improvement in ankle dorsiflexion (mean, 24.7° [preoperatively] vs 27.0° [final follow-up]; P = .049); however, they demonstrated substantial improvement in the FFI (mean, 20.5 [preoperatively] vs 2.7 [final follow-up]; P \ .001). Postoperatively, 84% of patients showed a recurrence of radiological osteophytes, with plain radiographs at final follow-up demonstrating no significant difference in the SMC grade (P = .107) or tibial osteophyte size (P = .212) compared with preoperative imaging. There was no significant effect of patient age, sex, body mass index, or SMC grade at the time of surgery on any of the postoperative outcome measures. Conclusion: In this prospective outcome study of 46 patients without osteoarthritis managed arthroscopically for anterior ankle impingement, the functional outcome scores had significantly improved at 5 years postoperatively despite a recurrence of radiographic osteophytes. Keywords: ankle impingement; ankle arthroscopic surgery; functional outcomes; athletes
1943 by Morris,14 ankle impingement is a common cause of ankle pain in athletic patients and is frequently associated with sporting activities involving repetitive forced dorsiflexion or plantar flexion of the ankle. The exact cause of this condition is debated but seems to involve osteophyte formation due to either repetitive microtrauma or macrotrauma associated with major injuries.4,9,18,20 Recently, the concept of cam-type impingement in the ankle has also been proposed,1 with certain anatomic features possibly resulting in altered ankle joint mechanics and impingement. Once anterior ankle impingement is established, repetitive impaction of the impinging tissue results in pain, restricted ankle motion, functional disability, and often traumatic chronic synovitis that may be resistant to nonoperative measures.10
Anterior ankle impingement is characterized by anterior ankle pain with restricted and painful dorsiflexion due to soft tissue11 or bony15 impingement. First described in
z Address correspondence to Matthew J. Boyle, FRACS, Unisports Sports Medicine, 71 Merton Road, PO Box 18067, Glenn Innes, Auckland 1743, New Zealand (e-mail: [email protected]). *Unisports Sports Medicine, Auckland, New Zealand. y Sports Medicine Center at Husky Stadium, Seattle, Washington, USA. The authors declared that they have no conflicts of interest in the authorship and publication of this contribution.
The American Journal of Sports Medicine, Vol. 42, No. 11 DOI: 10.1177/0363546514550976 Ó 2014 The Author(s)
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Arthroscopic Treatment of Ankle Impingement
The treatment of patients with anterior ankle impingement who fail nonoperative management typically involves arthroscopic or open surgical debridement of the impinging osteophytes and soft tissue. While successful open treatment of anterior ankle impingement has been reported,8,17 arthroscopic treatment of this condition has become increasingly popular2,4,5,13,17,19,22,23 because of the benefits of reduced recovery time and earlier return to sports compared with open debridement.17 Promising short-term arthroscopic results have been reported2,4,5,13,17,19,23; however, only 1 midterm study has been presented to date.22 Furthermore, many previous studies have included mixed diagnoses, including large numbers of patients with osteoarthritis.5,22,23 It therefore remains unclear as to the expected midterm outcomes of patients without arthritis and whether osteophytes in such patients recur over time. The aims of this prospective study were to determine the minimum 5-year clinical, functional, and radiological outcomes after arthroscopic treatment of anterior ankle impingement.
MATERIALS AND METHODS After ethical review board approval, a consecutive series of patients with anterior ankle impingement seen at our institution from September 1999 to March 2006, who had persistent ankle pain and associated activity restrictions despite at least 6 months of nonoperative management (rest, nonsteroidal anti-inflammatory medication, physical therapy, ankle bracing, shoe modification) and were scheduled for arthroscopic surgery, were assessed for study inclusion. Weightbearing plain radiography and magnetic resonance imaging (MRI) of the affected ankle were performed preoperatively. Patients with osteochondral talar dome lesions, talar dome fractures, or avascular necrosis of the talus on MRI; joint space narrowing of the tibiotalar, subtalar, or midtarsal joints on plain radiography; worse than Outerbridge16 grade I changes to either the distal tibial or talar dome articular cartilage on arthroscopic examination; tibiotalar instability on examination under anesthetics; or a history of ankle fractures were excluded from the study. All patients prospectively gave informed consent to participate in the study. All included study patients had single-leg weightbearing ankle dorsiflexion clinically measured, the Foot Functional Index (FFI) completed,7 and exercise activity levels assessed preoperatively by an independent orthopaedic sports medicine clinician (not involved in patient care), and preoperative weightbearing anteroposterior and lateral plain ankle radiographs undertaken by an experienced musculoskeletal radiographer were recorded. With respect to the exercise activity level, all patients were asked to quantify the number of exercise sessions undertaken in the week immediately before assessment (0, 1-2, 3-4, or 5 sessions) and the mean duration of exercise sessions during that week (\30, 30-60, 60-90, 90-120, or .120 minutes). Although not validated, these 2 exercise activity questions were selected as a simple measure to broadly compare patient activity preoperatively and postoperatively. Preoperative
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and postoperative plain radiography was not standardized for the purposes of this study but rather was undertaken to include anteroposterior and lateral radiographs of the tibiotalar joint according to standard local radiography protocols for the assessment of ankle pain. Preoperative radiographs were assessed for Scranton and McDermott classification (SMC)17 grade and tibial osteophyte size by an orthopaedic sports medicine fellow who was blinded to patient outcomes. All study patients underwent standardized outpatient surgery, with arthroscopic debridement of impinging bony and soft tissue performed by 1 of the 2 senior authors (S.J.W. and B.C.T.) utilizing standard anterolateral and anteromedial arthroscopic portals without the use of intraoperative radiographic imaging. All patients followed a uniform postoperative management program, with immobilization for the first postoperative week and partial weightbearing in a walking boot for 2 weeks. Once the portals healed, a nonimpacting cycling, stretching, and waterbased rehabilitation program was commenced. Patients returned to running no sooner than 4 weeks after surgery. Postoperatively, patients were assessed by an independent orthopaedic surgeon at 6 weeks, 6 months, and 12 months and then at 1-year intervals after surgery until a minimum of 5 years’ follow-up had been achieved. Single-leg weightbearing ankle dorsiflexion, FFI, exercise activity level (number of exercise sessions undertaken in the week immediately before assessment and the mean duration of exercise sessions during that week), and plain radiographs were recorded at each time point. Final postoperative radiographic analysis was undertaken by an independent orthopaedic sports medicine fellow who was blinded to patient outcomes but was not blinded to the follow-up time. Final data analysis was undertaken by an independent orthopaedic sports medicine fellow.
Methodological Considerations The FFI is a validated, self-reported instrument for the assessment of multiple dimensions of foot function based on patient-centered values. It consists of 23 items divided into 3 subscales that quantify the effect of foot pathological disorders on patients’ pain, disability, and activity limitation, with a lower score indicating superior function.7 The FFI has been found to have good reliability and validity.6,7,12 The SMC17 grade is a widely used classification system that categorizes anterior ankle impingement into 4 grades according to lateral ankle plain radiography: grade 1 when a tibial osteophyte is \3 mm, grade 2 when the osteophyte is .3 mm, grade 3 when there are both tibial and talar osteophytes, and grade 4 when there is associated joint space narrowing.
Statistical Analysis Comparisons of preoperative and postoperative scores were made using paired t tests. The associations between baseline measures and postoperative scores were tested using independent t tests for patient sex and Pearson
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TABLE 1 Results of Arthroscopic Treatment of Anterior Ankle Impingement at Minimum 5-Year Follow-up (N = 46 Patients)a Variable
Preoperative
Final Follow-up
Ankle dorsiflexion, deg FFI score Pain subscale Difficulty subscale Activity subscale SMC grade, median 6 SD Tibial osteophyte size, mm
24.7 20.5 25.0 21.6 13.3 2.0 5.1
27.0 2.7 3.1 3.1 1.2 2.0 4.3
6 6 6 6 6 6 6
6.3 17.6 21.0 22.7 15.5 0.7 2.7
6 6 6 6 6 6 6
7.5 4.8 5.2 6.9 3.4 0.9 3.1
P Value .049 \.001 \.001 \.001 \.001 .107 .212
a Values are reported as mean 6 SD unless otherwise indicated. FFI, Foot Function Index; SMC, Scranton and McDermott classification.
correlation coefficients for continuous baseline variables. A 2-tailed P value of \.05 was taken to indicate statistical significance.
RESULTS We enrolled 50 eligible patients during the study period. Of these patients, 3 were lost to follow-up, and 1 died before study completion, leaving 46 patients available for clinical, functional, and plain radiographic assessments with a minimum 5-year follow-up.
Baseline Information At the time of surgery, there were 42 male and 4 female patients, with a mean age of 29 years (range, 16-44 years) and a mean body mass index (BMI) of 26.7 kg/m2 (range, 19.8-36.0 kg/m2). All patients participated in competitive sports preoperatively, with the primary sport being rugby in 17 patients (37.0%), soccer in 10 patients (21.7%), rugby league in 2 patients (4.4%), tennis in 2 patients (4.4%), and other in 15 patients (32.6%); 40 patients participated in local or regional club-level sports, and 6 patients participated in professional or international competitions. Preoperatively, the mean ankle dorsiflexion was 24.7°, and the mean FFI was 20.5 (Table 1). Preoperative ankle radiographs demonstrated a median SMC grade of 2 (range, 1-3) and a mean tibial osteophyte size of 5.1 mm (range, 1-10 mm).
Postoperative Outcomes The mean follow-up duration was 5.1 years (range, 5.0-7.5 years). The postoperative clinical examination demonstrated improvement in the mean ankle dorsiflexion to 28° at 1-year follow-up (P \ .001) and 27° at final followup (P = .049) (Table 1). The functional assessment demonstrated substantial postoperative improvement in the mean FFI to 3.8 at 1-year follow-up (P \ .001) and 2.7 at final follow-up (P \ .001). Every FFI subscale also
Figure 1. Weightbearing lateral radiographs of the ankle in terminal dorsiflexion of a 26-year-old male patient. (A) Preoperative radiograph, demonstrating anterior ankle impingement with a prominent tibial osteophyte (Scranton and McDermott classification grade 2). (B) Radiograph taken 6 weeks after arthroscopic treatment, demonstrating satisfactory removal of an anterior tibial osteophyte. (C) Radiograph taken 5 years after arthroscopic treatment, demonstrating the recurrence of an anterior tibial osteophyte. (D) Weightbearing anteroposterior radiograph of the ankle 5 years after arthroscopic treatment, demonstrating no significant osteoarthritic change. The 5-year functional scores for this patient were excellent.
improved significantly after surgery (all P \ .001). There was no significant change in the exercise activity level between the preoperative and 1-year status (P = .185) or between the preoperative and final postoperative status (P = .147). Compared with preoperatively, 22 patients increased, 19 patients decreased, and 5 patients showed no change in exercise frequency or duration at 1-year follow-up, and 21 patients increased, 21 patients decreased, and 4 patients showed no change in exercise frequency or duration at final follow-up. Plain radiography at 6 weeks postoperatively demonstrated complete osteophyte resection in all patients. At final follow-up, osteophytes typically had recurred (Figure 1), with plain radiographs demonstrating no significant difference in the SMC grade (median, grade 2 [preoperative and final follow-up]; P = .107) or tibial osteophyte size (mean, 5.1 mm [preoperative] vs 4.3 mm [final follow-up]; P = .212) compared with preoperative imaging (Table 1). Correlation analyses demonstrated significant positive associations between the preoperative ankle dorsiflexion and postoperative ankle dorsiflexion (r = 0.41, P = .005) and between the preoperative tibial osteophyte size and postoperative SMC grade (r = 0.41, P = .029). There were
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Vol. 42, No. 11, 2014
Arthroscopic Treatment of Ankle Impingement
no significant effects of baseline patient age, sex, BMI, or SMC grade on any of the postoperative outcome measures.
DISCUSSION Good short-term outcomes after arthroscopic treatment of anterior ankle impingement have been reported2,4,5,13,17,19,23; however, midterm studies are limited. Our results compare favorably with those of the only other midterm study published to date, which was a series of 57 patients, with a mean age of 36 years, who were assessed at a minimum of 5 years after arthroscopic management of anterior ankle impingement.22 At a mean follow-up of 6.5 years, the overall patient satisfaction score in that study by Tol et al22 was 74%, and the overall successful treatment score was 65% (based on the lowest score for pain, swelling, stiffness, limping, or activity), with better results seen in patients without preoperative joint space narrowing. In the present study, we excluded patients with preoperative degenerative joint disease. In our study, we have presented clinical examination results, in addition to radiological and functional outcomes, at a minimum of 5 years after arthroscopic management of anterior ankle impingement. Our clinical results are interesting in that although we observed a statistically significant improvement in ankle dorsiflexion after surgery, this improvement was small and of questionable clinical significance. It is difficult to know why there is a limited improvement in ankle dorsiflexion after surgery both at early and midterm follow-ups. We hypothesize that posterior tibiotalar capsular contraction develops preoperatively in these patients, which restricts postoperative ankle dorsiflexion despite the removal of impinging bony and soft tissue anteriorly. Anterior osteophytes typically recur postoperatively, which may also contribute to the minimal postoperative improvement in ankle motion seen at midterm follow-up. Furthermore, the patients in our series did not have dramatically reduced ankle dorsiflexion preoperatively,3 which may have reduced the potential for substantial improvements postoperatively. In any case, it is important for patients to be advised that although improvements in ankle dorsiflexion after surgery may be limited, anterior ankle pain with dorsiflexion is reliably improved. Previous studies have recorded satisfactory early functional results after arthroscopic anterior ankle impingement surgery2,4,5,17,19,23; however, it is unclear whether these good results persist with time. The patients in our study displayed significant functional improvement at 1 year postoperatively, and importantly, this improvement was maintained at a minimum of 5 years postoperatively across all FFI subscales. This midterm persistence of satisfactory postoperative function was also observed in the midterm study of Tol et al22 and strongly supports arthroscopic treatment as a successful surgical option in patients with anterior ankle impingement. We also found that after surgery, our patients were able to return to at least the same level of exercise that they undertook preoperatively, which is an important finding in this young, athletic
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population. It is important to note that while we did not detect a significant improvement in exercise frequency or duration after surgery, this is likely a reflection on the shortcomings of the coarse measure of exercise activity levels that we employed; the postoperative improvements in the FFI suggest that our patient group experienced a positive, durable response to surgery. It is interesting to note that while postoperative function remained excellent, osteophytes typically recurred in our patients, with no significant difference in the median SMC grade between preoperative and final follow-up imaging. This postoperative recurrence of osteophytes, with the maintenance of good functional results, has been observed by previous authors.9,22 It is generally accepted that the recurrent osteophytes themselves are not painful in these patients.22 During terminal dorsiflexion, hypertrophic synovium and scar tissue become compressed between the anterior osteophytes, causing pain and swelling. The arthroscopic removal of osteophytes along with synovectomy and the removal of painful impinging soft tissue allow the pathoanatomy to be reversed. While we did not undertake repeat arthroscopic surgery, our positive functional results suggest that although the osteophytes recur, the painful hypertrophic synovium and scar tissue do not. It is important to note that despite the recurrence of osteophytes at midterm follow-up, the functional results in our patients remained excellent. This information is essential to convey to patients preoperatively, before treatment, so that they are adequately informed. Our study has a number of limitations. First, preoperative and postoperative plain radiography was not standardized, which may produce inaccuracies in the interpretation of radiographic results. Although arthroscopic assessment indicated the complete removal of anterior osteophytes, the lack of radiographic standardization and possible variability within the technique of lateral projection raise the possibility that early postoperative radiographs failed to demonstrate residual osteophytes. In addition, the radiographs were interpreted by an orthopaedic sports medicine fellow who was not blinded to the follow-up time, which introduces the possibility of confirmation bias. Furthermore, previous authors21 have indicated that oblique ankle radiographs, in addition to standard ankle radiography, may increase the diagnostic sensitivity in patients with suspected anterior ankle impingement. We believe that subtle radiographic differences have questionable clinical relevance, however, and the SMC grade remains a relatively broad, clinically relevant classification system. Therefore, our radiographic interpretation likely remains valid. Second, only 1 functional assessment tool was employed. The FFI is a validated scoring system that has been widely employed to assess the outcomes of ankle surgery,6,7,12 with the patient-centered, self-reported nature of the FFI likely providing a very relevant indication of patient outcomes. Third, we did not use a validated measure of patient exercise activity levels but rather assessed exercise activity using 2 simple, reproducible questions that we believe can be used to broadly compare patient activity
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preoperatively and postoperatively. Finally, we only achieved a minimum of 5 years’ follow-up; further followup is desirable to confirm the long-term persistence of our positive midterm patient outcomes. In this prospective outcome study of 46 patients without degenerative ankle arthritis managed arthroscopically for anterior ankle impingement, we found patient function to be significantly improved at 1 year after surgery, with maintenance of this improvement at a minimum of 5 years postoperatively. Patients managed arthroscopically for anterior ankle impingement can be advised that although radiographic osteophytes may recur, excellent midterm functional outcomes are expected.
ACKNOWLEDGMENT The authors sincerely thank Associate Professor Christopher Frampton for his statistical assistance and Dr Annunziato Amendola for his kind review.
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