Systematic Review
Gait and Lower Extremity Kinematic Analysis as an Outcome Measure After Femoroacetabular Impingement Surgery Hussain Alradwan, M.D., F.R.C.S.C., Moin Khan, M.D., Maggie Hamel-Smith Grassby, Asheesh Bedi, M.D., Marc J. Philippon, M.D., and Olufemi R. Ayeni, M.D., M.Sc., F.R.C.S.C.
Purpose: Lower extremity and pelvis kinematics have been shown to be abnormal in patients with femoroacetabular impingement (FAI). We conducted this systematic review to evaluate the current status of gait and lower extremity kinematics as an outcome measure in patients treated surgically for FAI. Methods: We searched the Embase, Medline, and PubMed databases for all reports of studies published through February 22, 2014, evaluating kinematic assessment of patients undergoing FAI surgery. A review of eligible studies was conducted, and the references were searched. Methodologic quality was evaluated for all studies that met the inclusion and exclusion criteria, and data were extracted regarding methods of kinematic assessment and clinical and kinematic outcomes. Results: We identified 633 reports, of which 5 met our eligibility criteria. These studies included a total of 58 patients with symptomatic FAI (age range, 18 to 50 years). All included studies were of moderate methodologic quality. Kinematic assessments were completed preoperatively and postoperatively with variable methodology and follow-up (range, 3 to 32 months). Most studies used highspeed motion-capture camera systems with reflective tracking markers to evaluate in vivo kinematic function. Of the 5 included studies, 3 documented kinematic improvements postoperatively particularly regarding sagittal hip range of motion primarily with flexion (weighted mean, 35.1 5.4 preoperatively and 37.8 6.3 postoperatively). Conclusions: Gait and lower extremity kinematics can be used as an outcome measure after FAI surgery. However, the lack of uniformity in the methodology used and underpowered case series limit the ability to identify clear and predictable differences after corrective surgery for FAI. Though statistically significant, functional outcome improvements were often conflicting and not necessarily of clinical significance. A uniform outcome measure and technique to reliably assess in vivo hip motion are required for future comparative studies. Level of Evidence: Level IV, systematic review of Level IV studies.
F
emoroacetabular impingement (FAI) is recognized as a common source of hip pain in the young adult.1,2 The condition is caused by impingement between the femoral head and acetabulum.1 Two
From the Division of Orthopaedic Surgery, Department of Surgery, McMaster University (H.A., M.K., M.H-S.G., O.R.A.), Hamilton, Ontario, Canada; Saudi Ministry of Higher Education (H.A.), Riyadh, Saudi Arabia; MedSport, Department of Orthopaedic Surgery, University of Michigan (A.B.), Ann Arbor, Michigan; and Steadman Philippon Research Institute (M.J.P.), Vail, Colorado, U.S.A. The authors report the following potential conflict of interest or source of funding: A.B. receives support from Smith & Nephew. M.J.P. receives support from Steadman Philippon Research Institute, Smith & Nephew, MIS, Ossur, Siemens, Vail Valley Medical Center, Arthrosurface, DonJoy, Linvatec, HIPCO. O.R.A. receives support from Smith & Nephew. Received April 21, 2014; accepted June 11, 2014. Address correspondence to Olufemi R. Ayeni, M.D., M.Sc., F.R.C.S.C., McMaster University Medical Center, 1200 Main St W, Room 4E17, Hamilton, ON L8N 3Z5, Canada. E-mail: [email protected] Ó 2014 by the Arthroscopy Association of North America 0749-8063/14329/$36.00 http://dx.doi.org/10.1016/j.arthro.2014.06.016
different types of FAI have been described, namely cam and pincer impingement.2 Cam impingement results from an aspherical portion of the femoral head and neck or a loss of offset of the femoral head-neck junction. Pincer impingement results from focal or global acetabular overcoverage.3 The collision between these 2 osseous structures can result in damage to the acetabular labrum and joint cartilage.1 This resulting impingement causes hip pain, restricted motion, and abnormal gait mechanics.4 Previous clinical studies have reported significant differences in joint kinematics and motion when comparing patients with and without FAI.5 More recently, studies comparing preoperative and postoperative kinematic analysis have raised the possibility of using gait and lower extremity kinematic assessment as an outcome measure after corrective FAI surgery.6 This systematic review aimed to evaluate and summarize the available literature regarding the use of gait and lower extremity kinematic analysis as an outcome measure for patients after corrective FAI surgery.
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Table 1. Search Strategy Medline 1. exp Femoroacetabular impingement/
Embase 1. exp femoroacetabular impingement/
2. exp Movement
2. exp treatment outcome/or exp outcomes research/ 3. exp outcome assessment/
3. exp Outcome Assessment (Health Care)/or exp Treatment Outcome/ 4. exp Gait/ 5. exp Walking/ 6. exp Biomechanical Phenomena/ 7. 2 or 3 or 4 or 5 or 6 8. 1 and 7 9. Limit 8 to (English language and humans) No. of studies: 139
PubMed (“femoroacetabular impingement”) AND (“outcome assessment health care” OR “treatment assessment outcome” OR “walking” OR “biomechanics/gait” OR “pathomechanics” OR “kinematics”) No. of studies: 207
4. exp biomechanics/ 5. exp kinematics/or exp gait/or exp walking 6. 2 or 3 or 4 or 5 7. 1 and 6 8. Limit 7 to (Human and English language) No. of studies: 287
NOTE: exp indicates an “exploded search”: by adding “exp” to a keyword (“exp keyword”) all the lower “branches” of this specific term are automatically included in the search as well.
Methods Identification of Studies We used multiple strategies to identify studies potentially eligible for inclusion. Two reviewers (H.A, M.H.) independently and in duplicate searched the Embase, Medline, and PubMed databases (1946 through February 22, 2014) for clinical studies evaluating kinematic assessment on patients undergoing FAI surgery. The search strategy combined the following search terms: femoroacetabular impingement, treatment outcome, outcome assessment, kinematics, gait, walking, and biomechanics (Table 1). A review of abstracts from major orthopaedic sports medicine conferences over the past 2 years was conducted to ensure unpublished data were not missed. We conducted a manual review of the reference lists of articles that were eligible for inclusion in our study to ascertain whether any additional studies were eligible for inclusion. We also used the “related articles” feature in PubMed for any study that met our criteria to identify any additional studies. The process of title screening and duplicate deletion was performed using a Web-based bibliography and database manager (RefWorks 2.0/2011; ProQuest, Ann Arbor, MI). Assessment of Study Eligibility Studies meeting the following inclusion criteria were eligible for inclusion in this review: (1) clinical studies with patients diagnosed and surgically treated with FAI and (2) outcomes evaluated with kinematic assessment. The exclusion criteria were as follows: (1) review articles, (2) basic science or technique papers, (3) radiographic/anatomic studies, (4) arthroplasty/non-FAI studies, (5) nonhuman/cadaveric studies, and (6) none English-language studies (Fig 1).
We made no restriction regarding the level of evidence or follow-up period to maximize potentially eligible studies. Assessment of Methodologic Quality Two reviewers (M.K, H.A.) independently graded the methodologic quality of all included studies. A quality assessment of all observational studies was planned a priori using the Methodological Index for NonRandomized Studies (MINORS) scale developed and validated by Slim et al.7 The ideal MINORS score is 24 for comparative studies and 16 for noncomparative studies. We graded all studies for the level of evidence according to the criteria of Wright and Swiontkowski.8 Data Abstraction Data were collected and recorded in a spreadsheet (Microsoft Excel; Microsoft, Redmond, WA) by the reviewers (H.A, M.H.). Abstracted data included the following information: author, year, method and instrument used in kinematic assessment, postoperative kinematic outcomes, and clinical outcome scores preoperatively and postoperatively. Statistical Analysis All abstracted data from all studies were organized into a table (Microsoft Word; Microsoft). Descriptive statistics were calculated to reflect the frequency of outcome measures. Interobserver agreement for study eligibility was calculated with the Cohen k coefficient.9 On the basis of the recommendations by Landis and Koch,10 a k of 0 to 0.2 represents slight agreement; 0.21 to 0.40, fair agreement; 0.41 to 0.60, moderate agreement; and 0.61 to 0.80, substantial agreement. A value beyond 0.80 is considered almost complete agreement.
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Results Study Identification We identified 633 potentially relevant citations from the initial search. After title review, 405 were identified for full abstract review, of which 32 required full text review. After application of the inclusion and exclusion criteria, 5 studies were selected for inclusion in this review.4,6,11-13 The k value for overall agreement between reviewers (H.A, M.H.) for the final eligibility decision was 0.89 (95% confidence interval, 0.78 to 0.99), indicating almost perfect agreement. Study and Patient Characteristics The sample sizes for included studies ranged from 10 to 17 patients. A total of 58 patients surgically treated for symptomatic FAI were included in this systematic review. Reported ages ranged from 18 to 50 years. Most of the included patients were men (27 of 38) in those studies that reported gender.6,12,13 The follow-up period ranged from 3 to 32 months. Two studies reported on 20 patients with only cam lesions,11,13 with the remaining studies reporting on cam, pincer, and mixed lesions. Most patients included in this review underwent arthroscopic corrective FAI surgery (38 of 58); the remainder underwent open or combined approaches (20 of 58) (Table 2).
Fig 1. Literature search outlining reasons for exclusion of identified articles.
Interobserver agreement for methodologic quality assessment was calculated using the intraclass correlation coefficient (ICC). Both the k and ICC were calculated using SPSS statistical analysis software (SPSS, Chicago, IL).
Study Quality There were 3 case series4,6,11 and 2 case-control studies12,13 included in this review. All included studies were of Level IV evidence. There were no Level I studies identified. We judged the case series to be of low methodologic quality, with mean MINORS scores of 10 of 16 for noncomparative studies and 18 of 24 for comparative studies. Agreement between reviewers (M.K, H.A.) in the assessment of study quality was excellent (ICC, 0.94; 95% confidence interval, 0.90 to 0.96). Kinematic Outcomes The included studies assessed kinematic outcomes through a variety of methods (Table 3). Of the 5 studies, 4
Table 2. Characteristics of Included Studies Study Bedi et al.4 Lamontagne et al.11 Rylander et al.6
Year Study Design 2011 Case series 2011 Case series 2011
Case series
Rylander et al.12 2013
Case control
Brisson et al.13
Case control
2013
SD, standard deviation.
Sample Size 10 10
Age, yr 25.9 (19-31) 18-50
11
19-44
17 patients and 35.4 8.9 17 controls (mean SD) 10 patients and 29.9 7.2 13 controls (mean SD)
Gender FAI Type Not reported Cam and/or pincer Not reported Cam 8 men and 3 women 12 men and 5 women 7 men and 3 women
Surgical Procedure Arthroscopic Open or combined
Follow-up 3 mo 8-32 mo
Cam/pincer/mixed
Arthroscopic
1 yr
3 pincer/14 mixed
Arthroscopic
1 yr
Cam
4 open/6 combined
10-32 mo
Table 3. Reported Kinematic Outcome Measures Kinematic Assessment Kinematic Instrumentation Preoperative Postoperative 3D reconstructions IR at 90 : 19.1 13.03 IR at 90 : 28.4 12.86 (P ¼ .0002) Flexion: 110.4 10 (P ¼ .002) and clinical hip Flexion: 107.4 11.6 ROM
Clinical Assessment
Lamontagne et al.,11 2011
Maximal squat assessment
High-speed motion capture (Vicon MX-13; Vicon) with reflective markers
Squat depth: 36.9% 12% All joint angles (hip/knee/ankle): 263.2 33.1
Squat depth: 33.2% 10.3% (P ¼ .027) All joint angles (hip/knee/ankle): 277.9 35.5 (P ¼ .006)
WOMAC: 78.1 14.3
Rylander et al.,6 2011
Gait assessment
High-speed motion capture (Qualisys) with reflective markers
HFA: 27.6 5 Reversal present in 5 of 11 patients
HFA: 30.7 4.3 (P ¼ .02) Reversal present in 2 of 11 patients
Rylander et al.,12 2013
Gait and stair climbing assessment
High-speed motion capture (Qualisys) with reflective markers
Gait Hip sag ROM: 40.0 5.7 Hip maximal flexion: 35.5 5.3 Hip rotation ROM: 11.3 3.5 Hip maximal IR: 6.5 4.6
Tegner activity Tegner activity scale: 6.1 scale: 4.1 1.7 VAS score: 1.9 (P ¼ .005) 4.6 2.2 VAS score: 2.18 1.5 (P ¼ .013) VAS score: VAS score: 2.1 2.1 4.9 1.9 (P .001) Tegner score: 3.7 1.7 Tegner score: 5.4 2.0 (P .001)
Brisson et al.,13 2013
Gait assessment
High-speed motion capture (Vicon MX-13) with reflective markers
Preoperative Postoperative IR at 90 : 17.5 IR at 90 : 11.37 31 8.43 mHHS: 65.86 mHHS: 6.66 89.1 13.02
Stairs Gait Hip sag ROM: Hip sag ROM: 54.5 3.3 42.5 7.5 (P ¼ .029) (P ¼ .780) Hip maximal Hip maximal flexion: 37.5 flexion: 66.2 5.9 7.1 (P ¼ .038) (P ¼ .971) Hip rotation Hip rotation ROM: 14.1 ROM: 13.6 5.1 .4 (P ¼ .890) (P ¼ .002) Hip maximal IR: Hip maximal IR: 8.7 4.4 10.3 5.6 (P ¼ .347) (P ¼ .027) No significant differences were detected between preoperative and WOMAC pain: postoperative groups on kinematic assessment 67.2 16.2 WOMAC stiffness: 67.4 16.2 WOMAC function: 82.4 15.4 Stairs Hip sag ROM: 54.8 3.7 Hip maximal flexion: 66.3 5.9 Hip rotation ROM: 13.8 3.9 Hip maximal IR: 7.1 6.4
WOMAC: 82.2 14.8
WOMAC pain: 80.6 14.7 (P ¼ .035) WOMAC stiffness: 65.9 18.5 (P > .05) WOMAC function: 84.6 17.6 (P > .05)
Key Findings Focal cam and/or rim osteoplasty can reliably improve hip kinematics and clinical ROM No significant differences between preoperative and postoperative kinematic assessments of maximal squat depth Surgical intervention for FAI restores more normal patterns of gait Hip kinematics improves postarthroscopic surgical intervention for walking but not for stair climbing
Gait biomechanics of FAI patients did not return to normal after surgery
NOTE. Data are presented as mean SD unless otherwise indicated. 3D, 3-dimensional; HFA, hip flexion angle; IR, internal rotation; mHHS, modified Harris Hip Score; SD, standard deviation; sag, sagittal plane; VAS, visual analog scale.
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Kinematic Assessment Virtual and clinical hip ROM
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Study Bedi et al.,4 2011
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used high-speed motion-capture camera systems with reflective markers affixed to the study subjects to evaluate kinematic motion. The systems used for this analysis were developed by either Vicon (Los Angeles, CA) or Qualisys (Gothenburg, Sweden). One study used highresolution 3-dimensional computed tomography reconstruction images of the lower extremities and correlated these with patients’ clinical range of motion (ROM).4 Variability in kinematic assessment was also apparent. Of the 4 studies reporting with motion capture, 2 reported on gait/level walking.6,13 One study reported on gait and stair climbing.12 Finally, 1 study reported on lower extremity and pelvis kinematics during squatting.11 A case-control study by Brisson et al.13 evaluated FAI treated through open or combined approaches and found no significant difference between preoperative and postoperative groups regarding hip frontal- and sagittal-plane ROM. In addition, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were obtained preoperatively and postoperatively and failed to show significant differences with the exception of the WOMAC pain subscale (67.2 16.2 to 80.6 14.7). In the case series by Bedi et al.,4 significant improvements in hip kinematics were noted through both clinical assessments and computer-generated 3-dimensional lower extremity reconstructions. Improvements were reported, including increases in hip flexion and internal rotation at 90 of hip flexion. Clinically, the mean modified Harris Hip Score improved from 65.86 6.66 preoperatively to 89.1 13.02 postoperatively. Lamontagne et al.11 reported in a case series that no significant improvement in pelvic angular displacements or overall pelvic motion occurred after FAI surgery. WOMAC scores were assessed, with a mean score improvement from 78.1 preoperatively to 82.2 postoperatively. The case series by Rylander et al.6 reported improvement in the sagittal-plane ROM. Abnormal gait kinematics disappeared or were reduced in 4 of 5 patients. Tegner scores were obtained, with improvement from the preoperative score of 4.1 to 6.1 postoperatively. Pain scores improved as well, from 4.6 to 2.1 on an 11-point pain scale survey. In a separate study, Rylander et al.12 assessed gait and stair climbing and noted improvement in hip sagittalplane ROM and internal rotation during walking; however, this improvement was not noted during stair climbing. Hip frontal-plane ROM remained significantly reduced after surgery. Pelvic transverse-plane ROM and maximum pelvic anterior tilt remained significantly increased in FAI patients after surgery. Functional outcomes were reported using the Tegner activity scale, with improvement from 3.7 (SD, 1.7) to 5.2 (SD, 1.9) postoperatively.
Of the 5 studies included in this review, 3 concluded that kinematic improvements occurred after FAI surgery.4,6,12 Pertinent data were pooled for the 3 studies evaluating and reporting gait kinematics, with 38 included patients.6,12,13 In 28 patients, or 73%, improvements in sagittal hip ROM, primarily with flexion, were shown postoperatively (weighted mean, 35.1 5.4 preoperatively to 37.8 6.25 postoperatively).
Discussion Key Findings This systematic review explores the utility of kinematic assessment after corrective FAI surgery. Although outcomes after FAI surgery are generally reported to be favorable, objective measures of gait and physical motion are not regularly evaluated after surgery. Given that FAI results from mechanical impingement between osseous structures, osteochondroplasty/rim decompression to correct the architecture of the hip should theoretically improve motion and gait kinematics. Consequently, gait analysis would offer a physician the opportunity to quantitatively and objectively assess functional improvement after surgery. Although studies, to date, have reported favorable changes in kinematics after corrective surgery, our results show that these are primarily small case series with a lack of consistency in the methodology of in vivo testing, as well as in the selected functional task to assess improvement. In this regard, the objective improvement in gait or other functional tasks after corrective FAI surgery cannot be reliably quantified based on the current literature. This highlights the need for standardized methods of assessing postsurgical kinematic measures after corrective FAI surgery. In general, the included studies reported modest improvements in functional outcome scores after FAI surgery. Most of these results, when statistically significant, did not exceed the threshold for minimally important patient differences. The minimally important difference is the smallest effect that an informed patient would perceive as valuable enough to justify a change in therapeutic management.14 Although we found that kinematic assessment after FAI surgery in many studies shows improvements in sagittal hip ROM, particularly with regard to flexion, it is important to note that the minimum improvement in terminal hip flexion and/or internal rotation to improve function has not been defined and may be variable based on patient expectations or sport-specific athletic demands. The potential of gait assessment to provide an objective measure of success after FAI surgery exists; however, the results of available studies do not clearly define the best available kinematic measurement tool, surgical technique, or functional tasks. In addition, gait abnormalities may persist after surgery for a number of
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reasons, including but not limited to residual pain, concomitant operative procedures (psoas release/ lengthening), incomplete osseous correction, time from surgery, and severity of initial disease, as well as the degree and quality of postoperative physical therapy. Future Directions Further research is required regarding developing an optimal measurement tool after corrective FAI surgery. The definition of more sensitive functional tasks to assess changes in terminal ROM after FAI surgery and to confirm the quality of the executed surgical correction is necessary. Our systematic review highlights the need for studies with larger sample sizes and standardized gait assessment methods. Correlating radiographic measures of impingement to gait and kinematic outcomes may help define the impact of FAI morphology on clinical outcomes. Consequently, future reporting measures may incorporate a composite score comprising functional outcomes, radiographic measures, gait assessment, and potentially, biomarkers in determining those patients who would benefit most from surgical intervention for FAI. Strengths This systematic review is the first evaluating kinematic assessment after corrective FAI surgery. The strengths of this study include broad search terms and duplicate assessment of study eligibility, as well as methodologic quality assessment of included studies. In addition, a search was completed of the unpublished literature to ensure a comprehensive search, and there were high levels of agreement between assessors regarding study inclusion and methodologic assessment. Limitations The limitations of our study relate to the size and study design of the included studies. All studies were of Level IV methodologic quality with small sample sizes. Most of the included studies did not perform sample size calculations; many studies had loss to follow-up and incomplete reporting of outcome data. Given the significant heterogeneity of included studies relating to patient interventions and outcome measurements, only a limited pooled analysis could be performed. A significant risk of bias exists with case series, and therefore the results of this review should be used to form the basis of well-designed prospective studies evaluating the kinematic outcomes after corrective FAI surgery.
Conclusions Gait and lower extremity kinematics can be used as an outcome measure after FAI surgery. However, the lack of uniformity in the methodology used and underpowered case series limit the ability to identify clear
and predictable differences after corrective surgery for FAI. Though statistically significant, functional outcome improvements were often conflicting and not necessarily of clinical significance. A uniform outcome measure and technique to reliably assess in vivo hip motion are required for future comparative studies.
References 1. Bedi A, Kelly BT, Khanduja V. Arthroscopic hip preservation surgery: Current concepts and perspective. Bone Joint J 2013;95:10-19. 2. Bedi A, Kelly BT. Femoroacetabular impingement. J Bone Joint Surg Am 2013;95:82-92. 3. Hetaimish BM, Khan M, Crouch S, et al. Consistency of reported outcomes after arthroscopic management of femoroacetabular impingement. Arthroscopy 2013;29: 780-787. 4. Bedi A, Dolan M, Hetsroni I, et al. Surgical treatment of femoroacetabular impingement improves hip kinematics: A computer-assisted model. Am J Sports Med 2011;39:43S-49S (suppl). 5. Kennedy MJ, Lamontagne M, Beaule PE. Femoroacetabular impingement alters hip and pelvic biomechanics during gait walking biomechanics of FAI. Gait Posture 2009;30:41-44. 6. Rylander JH, Shu B, Andriacchi TP, Safran MR. Preoperative and postoperative sagittal plane hip kinematics in patients with femoroacetabular impingement during level walking. Am J Sports Med 2011;39(suppl):36S-42S. 7. Slim K, Nini E, Forestier D, Kwiatkowski F, Panis Y, Chipponi J. Methodological Index for Non-Randomized Studies (MINORS): Development and validation of a new instrument. ANZ J Surg 2003;73:712-716. 8. Wright JG, Swiontkowski MF. Introducing a new journal section: Evidence-based orthopaedics. J Bone Joint Surg Am 2000;82:759-760. 9. Fleiss JL. Statistical methods for rates and proportions, Ed 2. New York: John Wiley and Sons, 1981. 10. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33: 159-174. 11. Lamontagne M, Brisson N, Kennedy MJ, Beaule PE. Preoperative and postoperative lower-extremity joint and pelvic kinematics during maximal squatting of patients with cam femoro-acetabular impingement. J Bone Joint Surg Am 2011;93:40-45 (suppl 2). 12. Rylander J, Shu B, Favre J, Safran M, Andriacchi T. Functional testing provides unique insights into the pathomechanics of femoroacetabular impingement and an objective basis for evaluating treatment outcome. J Orthop Res 2013;31:1461-1468. 13. Brisson N, Lamontagne M, Kennedy MJ, Beaule PE. The effects of cam femoroacetabular impingement corrective surgery on lower-extremity gait biomechanics. Gait Posture 2013;37:258-263. 14. ISAKOS Scientific Committee, Audige L, Ayeni OR, et al. A practical guide to research: Design, execution, and publication. Arthroscopy 2011;27:S1-S112 (4 suppl).
Gait and Lower Extremity Kinematic Analysis as an Outcome Measure After Femoroacetabular Impingement Surgery Hussain Alradwan, M.D., F.R.C.S.C., Moin Khan, M.D., Maggie Hamel-Smith Grassby, Asheesh Bedi, M.D., Marc J. Philippon, M.D., and Olufemi R. Ayeni, M.D., M.Sc., F.R.C.S.C.
Purpose: Lower extremity and pelvis kinematics have been shown to be abnormal in patients with femoroacetabular impingement (FAI). We conducted this systematic review to evaluate the current status of gait and lower extremity kinematics as an outcome measure in patients treated surgically for FAI. Methods: We searched the Embase, Medline, and PubMed databases for all reports of studies published through February 22, 2014, evaluating kinematic assessment of patients undergoing FAI surgery. A review of eligible studies was conducted, and the references were searched. Methodologic quality was evaluated for all studies that met the inclusion and exclusion criteria, and data were extracted regarding methods of kinematic assessment and clinical and kinematic outcomes. Results: We identified 633 reports, of which 5 met our eligibility criteria. These studies included a total of 58 patients with symptomatic FAI (age range, 18 to 50 years). All included studies were of moderate methodologic quality. Kinematic assessments were completed preoperatively and postoperatively with variable methodology and follow-up (range, 3 to 32 months). Most studies used highspeed motion-capture camera systems with reflective tracking markers to evaluate in vivo kinematic function. Of the 5 included studies, 3 documented kinematic improvements postoperatively particularly regarding sagittal hip range of motion primarily with flexion (weighted mean, 35.1 5.4 preoperatively and 37.8 6.3 postoperatively). Conclusions: Gait and lower extremity kinematics can be used as an outcome measure after FAI surgery. However, the lack of uniformity in the methodology used and underpowered case series limit the ability to identify clear and predictable differences after corrective surgery for FAI. Though statistically significant, functional outcome improvements were often conflicting and not necessarily of clinical significance. A uniform outcome measure and technique to reliably assess in vivo hip motion are required for future comparative studies. Level of Evidence: Level IV, systematic review of Level IV studies.
F
emoroacetabular impingement (FAI) is recognized as a common source of hip pain in the young adult.1,2 The condition is caused by impingement between the femoral head and acetabulum.1 Two
From the Division of Orthopaedic Surgery, Department of Surgery, McMaster University (H.A., M.K., M.H-S.G., O.R.A.), Hamilton, Ontario, Canada; Saudi Ministry of Higher Education (H.A.), Riyadh, Saudi Arabia; MedSport, Department of Orthopaedic Surgery, University of Michigan (A.B.), Ann Arbor, Michigan; and Steadman Philippon Research Institute (M.J.P.), Vail, Colorado, U.S.A. The authors report the following potential conflict of interest or source of funding: A.B. receives support from Smith & Nephew. M.J.P. receives support from Steadman Philippon Research Institute, Smith & Nephew, MIS, Ossur, Siemens, Vail Valley Medical Center, Arthrosurface, DonJoy, Linvatec, HIPCO. O.R.A. receives support from Smith & Nephew. Received April 21, 2014; accepted June 11, 2014. Address correspondence to Olufemi R. Ayeni, M.D., M.Sc., F.R.C.S.C., McMaster University Medical Center, 1200 Main St W, Room 4E17, Hamilton, ON L8N 3Z5, Canada. E-mail: [email protected] Ó 2014 by the Arthroscopy Association of North America 0749-8063/14329/$36.00 http://dx.doi.org/10.1016/j.arthro.2014.06.016
different types of FAI have been described, namely cam and pincer impingement.2 Cam impingement results from an aspherical portion of the femoral head and neck or a loss of offset of the femoral head-neck junction. Pincer impingement results from focal or global acetabular overcoverage.3 The collision between these 2 osseous structures can result in damage to the acetabular labrum and joint cartilage.1 This resulting impingement causes hip pain, restricted motion, and abnormal gait mechanics.4 Previous clinical studies have reported significant differences in joint kinematics and motion when comparing patients with and without FAI.5 More recently, studies comparing preoperative and postoperative kinematic analysis have raised the possibility of using gait and lower extremity kinematic assessment as an outcome measure after corrective FAI surgery.6 This systematic review aimed to evaluate and summarize the available literature regarding the use of gait and lower extremity kinematic analysis as an outcome measure for patients after corrective FAI surgery.
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Table 1. Search Strategy Medline 1. exp Femoroacetabular impingement/
Embase 1. exp femoroacetabular impingement/
2. exp Movement
2. exp treatment outcome/or exp outcomes research/ 3. exp outcome assessment/
3. exp Outcome Assessment (Health Care)/or exp Treatment Outcome/ 4. exp Gait/ 5. exp Walking/ 6. exp Biomechanical Phenomena/ 7. 2 or 3 or 4 or 5 or 6 8. 1 and 7 9. Limit 8 to (English language and humans) No. of studies: 139
PubMed (“femoroacetabular impingement”) AND (“outcome assessment health care” OR “treatment assessment outcome” OR “walking” OR “biomechanics/gait” OR “pathomechanics” OR “kinematics”) No. of studies: 207
4. exp biomechanics/ 5. exp kinematics/or exp gait/or exp walking 6. 2 or 3 or 4 or 5 7. 1 and 6 8. Limit 7 to (Human and English language) No. of studies: 287
NOTE: exp indicates an “exploded search”: by adding “exp” to a keyword (“exp keyword”) all the lower “branches” of this specific term are automatically included in the search as well.
Methods Identification of Studies We used multiple strategies to identify studies potentially eligible for inclusion. Two reviewers (H.A, M.H.) independently and in duplicate searched the Embase, Medline, and PubMed databases (1946 through February 22, 2014) for clinical studies evaluating kinematic assessment on patients undergoing FAI surgery. The search strategy combined the following search terms: femoroacetabular impingement, treatment outcome, outcome assessment, kinematics, gait, walking, and biomechanics (Table 1). A review of abstracts from major orthopaedic sports medicine conferences over the past 2 years was conducted to ensure unpublished data were not missed. We conducted a manual review of the reference lists of articles that were eligible for inclusion in our study to ascertain whether any additional studies were eligible for inclusion. We also used the “related articles” feature in PubMed for any study that met our criteria to identify any additional studies. The process of title screening and duplicate deletion was performed using a Web-based bibliography and database manager (RefWorks 2.0/2011; ProQuest, Ann Arbor, MI). Assessment of Study Eligibility Studies meeting the following inclusion criteria were eligible for inclusion in this review: (1) clinical studies with patients diagnosed and surgically treated with FAI and (2) outcomes evaluated with kinematic assessment. The exclusion criteria were as follows: (1) review articles, (2) basic science or technique papers, (3) radiographic/anatomic studies, (4) arthroplasty/non-FAI studies, (5) nonhuman/cadaveric studies, and (6) none English-language studies (Fig 1).
We made no restriction regarding the level of evidence or follow-up period to maximize potentially eligible studies. Assessment of Methodologic Quality Two reviewers (M.K, H.A.) independently graded the methodologic quality of all included studies. A quality assessment of all observational studies was planned a priori using the Methodological Index for NonRandomized Studies (MINORS) scale developed and validated by Slim et al.7 The ideal MINORS score is 24 for comparative studies and 16 for noncomparative studies. We graded all studies for the level of evidence according to the criteria of Wright and Swiontkowski.8 Data Abstraction Data were collected and recorded in a spreadsheet (Microsoft Excel; Microsoft, Redmond, WA) by the reviewers (H.A, M.H.). Abstracted data included the following information: author, year, method and instrument used in kinematic assessment, postoperative kinematic outcomes, and clinical outcome scores preoperatively and postoperatively. Statistical Analysis All abstracted data from all studies were organized into a table (Microsoft Word; Microsoft). Descriptive statistics were calculated to reflect the frequency of outcome measures. Interobserver agreement for study eligibility was calculated with the Cohen k coefficient.9 On the basis of the recommendations by Landis and Koch,10 a k of 0 to 0.2 represents slight agreement; 0.21 to 0.40, fair agreement; 0.41 to 0.60, moderate agreement; and 0.61 to 0.80, substantial agreement. A value beyond 0.80 is considered almost complete agreement.
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Results Study Identification We identified 633 potentially relevant citations from the initial search. After title review, 405 were identified for full abstract review, of which 32 required full text review. After application of the inclusion and exclusion criteria, 5 studies were selected for inclusion in this review.4,6,11-13 The k value for overall agreement between reviewers (H.A, M.H.) for the final eligibility decision was 0.89 (95% confidence interval, 0.78 to 0.99), indicating almost perfect agreement. Study and Patient Characteristics The sample sizes for included studies ranged from 10 to 17 patients. A total of 58 patients surgically treated for symptomatic FAI were included in this systematic review. Reported ages ranged from 18 to 50 years. Most of the included patients were men (27 of 38) in those studies that reported gender.6,12,13 The follow-up period ranged from 3 to 32 months. Two studies reported on 20 patients with only cam lesions,11,13 with the remaining studies reporting on cam, pincer, and mixed lesions. Most patients included in this review underwent arthroscopic corrective FAI surgery (38 of 58); the remainder underwent open or combined approaches (20 of 58) (Table 2).
Fig 1. Literature search outlining reasons for exclusion of identified articles.
Interobserver agreement for methodologic quality assessment was calculated using the intraclass correlation coefficient (ICC). Both the k and ICC were calculated using SPSS statistical analysis software (SPSS, Chicago, IL).
Study Quality There were 3 case series4,6,11 and 2 case-control studies12,13 included in this review. All included studies were of Level IV evidence. There were no Level I studies identified. We judged the case series to be of low methodologic quality, with mean MINORS scores of 10 of 16 for noncomparative studies and 18 of 24 for comparative studies. Agreement between reviewers (M.K, H.A.) in the assessment of study quality was excellent (ICC, 0.94; 95% confidence interval, 0.90 to 0.96). Kinematic Outcomes The included studies assessed kinematic outcomes through a variety of methods (Table 3). Of the 5 studies, 4
Table 2. Characteristics of Included Studies Study Bedi et al.4 Lamontagne et al.11 Rylander et al.6
Year Study Design 2011 Case series 2011 Case series 2011
Case series
Rylander et al.12 2013
Case control
Brisson et al.13
Case control
2013
SD, standard deviation.
Sample Size 10 10
Age, yr 25.9 (19-31) 18-50
11
19-44
17 patients and 35.4 8.9 17 controls (mean SD) 10 patients and 29.9 7.2 13 controls (mean SD)
Gender FAI Type Not reported Cam and/or pincer Not reported Cam 8 men and 3 women 12 men and 5 women 7 men and 3 women
Surgical Procedure Arthroscopic Open or combined
Follow-up 3 mo 8-32 mo
Cam/pincer/mixed
Arthroscopic
1 yr
3 pincer/14 mixed
Arthroscopic
1 yr
Cam
4 open/6 combined
10-32 mo
Table 3. Reported Kinematic Outcome Measures Kinematic Assessment Kinematic Instrumentation Preoperative Postoperative 3D reconstructions IR at 90 : 19.1 13.03 IR at 90 : 28.4 12.86 (P ¼ .0002) Flexion: 110.4 10 (P ¼ .002) and clinical hip Flexion: 107.4 11.6 ROM
Clinical Assessment
Lamontagne et al.,11 2011
Maximal squat assessment
High-speed motion capture (Vicon MX-13; Vicon) with reflective markers
Squat depth: 36.9% 12% All joint angles (hip/knee/ankle): 263.2 33.1
Squat depth: 33.2% 10.3% (P ¼ .027) All joint angles (hip/knee/ankle): 277.9 35.5 (P ¼ .006)
WOMAC: 78.1 14.3
Rylander et al.,6 2011
Gait assessment
High-speed motion capture (Qualisys) with reflective markers
HFA: 27.6 5 Reversal present in 5 of 11 patients
HFA: 30.7 4.3 (P ¼ .02) Reversal present in 2 of 11 patients
Rylander et al.,12 2013
Gait and stair climbing assessment
High-speed motion capture (Qualisys) with reflective markers
Gait Hip sag ROM: 40.0 5.7 Hip maximal flexion: 35.5 5.3 Hip rotation ROM: 11.3 3.5 Hip maximal IR: 6.5 4.6
Tegner activity Tegner activity scale: 6.1 scale: 4.1 1.7 VAS score: 1.9 (P ¼ .005) 4.6 2.2 VAS score: 2.18 1.5 (P ¼ .013) VAS score: VAS score: 2.1 2.1 4.9 1.9 (P .001) Tegner score: 3.7 1.7 Tegner score: 5.4 2.0 (P .001)
Brisson et al.,13 2013
Gait assessment
High-speed motion capture (Vicon MX-13) with reflective markers
Preoperative Postoperative IR at 90 : 17.5 IR at 90 : 11.37 31 8.43 mHHS: 65.86 mHHS: 6.66 89.1 13.02
Stairs Gait Hip sag ROM: Hip sag ROM: 54.5 3.3 42.5 7.5 (P ¼ .029) (P ¼ .780) Hip maximal Hip maximal flexion: 37.5 flexion: 66.2 5.9 7.1 (P ¼ .038) (P ¼ .971) Hip rotation Hip rotation ROM: 14.1 ROM: 13.6 5.1 .4 (P ¼ .890) (P ¼ .002) Hip maximal IR: Hip maximal IR: 8.7 4.4 10.3 5.6 (P ¼ .347) (P ¼ .027) No significant differences were detected between preoperative and WOMAC pain: postoperative groups on kinematic assessment 67.2 16.2 WOMAC stiffness: 67.4 16.2 WOMAC function: 82.4 15.4 Stairs Hip sag ROM: 54.8 3.7 Hip maximal flexion: 66.3 5.9 Hip rotation ROM: 13.8 3.9 Hip maximal IR: 7.1 6.4
WOMAC: 82.2 14.8
WOMAC pain: 80.6 14.7 (P ¼ .035) WOMAC stiffness: 65.9 18.5 (P > .05) WOMAC function: 84.6 17.6 (P > .05)
Key Findings Focal cam and/or rim osteoplasty can reliably improve hip kinematics and clinical ROM No significant differences between preoperative and postoperative kinematic assessments of maximal squat depth Surgical intervention for FAI restores more normal patterns of gait Hip kinematics improves postarthroscopic surgical intervention for walking but not for stair climbing
Gait biomechanics of FAI patients did not return to normal after surgery
NOTE. Data are presented as mean SD unless otherwise indicated. 3D, 3-dimensional; HFA, hip flexion angle; IR, internal rotation; mHHS, modified Harris Hip Score; SD, standard deviation; sag, sagittal plane; VAS, visual analog scale.
H. ALRADWAN ET AL.
Kinematic Assessment Virtual and clinical hip ROM
4
Study Bedi et al.,4 2011
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GAIT AND LOWER EXTREMITY ANALYSIS
used high-speed motion-capture camera systems with reflective markers affixed to the study subjects to evaluate kinematic motion. The systems used for this analysis were developed by either Vicon (Los Angeles, CA) or Qualisys (Gothenburg, Sweden). One study used highresolution 3-dimensional computed tomography reconstruction images of the lower extremities and correlated these with patients’ clinical range of motion (ROM).4 Variability in kinematic assessment was also apparent. Of the 4 studies reporting with motion capture, 2 reported on gait/level walking.6,13 One study reported on gait and stair climbing.12 Finally, 1 study reported on lower extremity and pelvis kinematics during squatting.11 A case-control study by Brisson et al.13 evaluated FAI treated through open or combined approaches and found no significant difference between preoperative and postoperative groups regarding hip frontal- and sagittal-plane ROM. In addition, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were obtained preoperatively and postoperatively and failed to show significant differences with the exception of the WOMAC pain subscale (67.2 16.2 to 80.6 14.7). In the case series by Bedi et al.,4 significant improvements in hip kinematics were noted through both clinical assessments and computer-generated 3-dimensional lower extremity reconstructions. Improvements were reported, including increases in hip flexion and internal rotation at 90 of hip flexion. Clinically, the mean modified Harris Hip Score improved from 65.86 6.66 preoperatively to 89.1 13.02 postoperatively. Lamontagne et al.11 reported in a case series that no significant improvement in pelvic angular displacements or overall pelvic motion occurred after FAI surgery. WOMAC scores were assessed, with a mean score improvement from 78.1 preoperatively to 82.2 postoperatively. The case series by Rylander et al.6 reported improvement in the sagittal-plane ROM. Abnormal gait kinematics disappeared or were reduced in 4 of 5 patients. Tegner scores were obtained, with improvement from the preoperative score of 4.1 to 6.1 postoperatively. Pain scores improved as well, from 4.6 to 2.1 on an 11-point pain scale survey. In a separate study, Rylander et al.12 assessed gait and stair climbing and noted improvement in hip sagittalplane ROM and internal rotation during walking; however, this improvement was not noted during stair climbing. Hip frontal-plane ROM remained significantly reduced after surgery. Pelvic transverse-plane ROM and maximum pelvic anterior tilt remained significantly increased in FAI patients after surgery. Functional outcomes were reported using the Tegner activity scale, with improvement from 3.7 (SD, 1.7) to 5.2 (SD, 1.9) postoperatively.
Of the 5 studies included in this review, 3 concluded that kinematic improvements occurred after FAI surgery.4,6,12 Pertinent data were pooled for the 3 studies evaluating and reporting gait kinematics, with 38 included patients.6,12,13 In 28 patients, or 73%, improvements in sagittal hip ROM, primarily with flexion, were shown postoperatively (weighted mean, 35.1 5.4 preoperatively to 37.8 6.25 postoperatively).
Discussion Key Findings This systematic review explores the utility of kinematic assessment after corrective FAI surgery. Although outcomes after FAI surgery are generally reported to be favorable, objective measures of gait and physical motion are not regularly evaluated after surgery. Given that FAI results from mechanical impingement between osseous structures, osteochondroplasty/rim decompression to correct the architecture of the hip should theoretically improve motion and gait kinematics. Consequently, gait analysis would offer a physician the opportunity to quantitatively and objectively assess functional improvement after surgery. Although studies, to date, have reported favorable changes in kinematics after corrective surgery, our results show that these are primarily small case series with a lack of consistency in the methodology of in vivo testing, as well as in the selected functional task to assess improvement. In this regard, the objective improvement in gait or other functional tasks after corrective FAI surgery cannot be reliably quantified based on the current literature. This highlights the need for standardized methods of assessing postsurgical kinematic measures after corrective FAI surgery. In general, the included studies reported modest improvements in functional outcome scores after FAI surgery. Most of these results, when statistically significant, did not exceed the threshold for minimally important patient differences. The minimally important difference is the smallest effect that an informed patient would perceive as valuable enough to justify a change in therapeutic management.14 Although we found that kinematic assessment after FAI surgery in many studies shows improvements in sagittal hip ROM, particularly with regard to flexion, it is important to note that the minimum improvement in terminal hip flexion and/or internal rotation to improve function has not been defined and may be variable based on patient expectations or sport-specific athletic demands. The potential of gait assessment to provide an objective measure of success after FAI surgery exists; however, the results of available studies do not clearly define the best available kinematic measurement tool, surgical technique, or functional tasks. In addition, gait abnormalities may persist after surgery for a number of
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reasons, including but not limited to residual pain, concomitant operative procedures (psoas release/ lengthening), incomplete osseous correction, time from surgery, and severity of initial disease, as well as the degree and quality of postoperative physical therapy. Future Directions Further research is required regarding developing an optimal measurement tool after corrective FAI surgery. The definition of more sensitive functional tasks to assess changes in terminal ROM after FAI surgery and to confirm the quality of the executed surgical correction is necessary. Our systematic review highlights the need for studies with larger sample sizes and standardized gait assessment methods. Correlating radiographic measures of impingement to gait and kinematic outcomes may help define the impact of FAI morphology on clinical outcomes. Consequently, future reporting measures may incorporate a composite score comprising functional outcomes, radiographic measures, gait assessment, and potentially, biomarkers in determining those patients who would benefit most from surgical intervention for FAI. Strengths This systematic review is the first evaluating kinematic assessment after corrective FAI surgery. The strengths of this study include broad search terms and duplicate assessment of study eligibility, as well as methodologic quality assessment of included studies. In addition, a search was completed of the unpublished literature to ensure a comprehensive search, and there were high levels of agreement between assessors regarding study inclusion and methodologic assessment. Limitations The limitations of our study relate to the size and study design of the included studies. All studies were of Level IV methodologic quality with small sample sizes. Most of the included studies did not perform sample size calculations; many studies had loss to follow-up and incomplete reporting of outcome data. Given the significant heterogeneity of included studies relating to patient interventions and outcome measurements, only a limited pooled analysis could be performed. A significant risk of bias exists with case series, and therefore the results of this review should be used to form the basis of well-designed prospective studies evaluating the kinematic outcomes after corrective FAI surgery.
Conclusions Gait and lower extremity kinematics can be used as an outcome measure after FAI surgery. However, the lack of uniformity in the methodology used and underpowered case series limit the ability to identify clear
and predictable differences after corrective surgery for FAI. Though statistically significant, functional outcome improvements were often conflicting and not necessarily of clinical significance. A uniform outcome measure and technique to reliably assess in vivo hip motion are required for future comparative studies.
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