Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-014-2944-2
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Change of gait in patients with lateral osteoarthritis of the knee after mobile-bearing unicompartmental knee arthroplasty J. B. Seeger • J. P. Schikschneit • C. Schuld • R. Rupp • S. Ja¨ger • H. Schmitt • G. S. Maier M. Clarius
•
Received: 20 August 2013 / Accepted: 10 March 2014 Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Patients with lateral osteoarthritis of the knee suffer not only from pain but also impaired gait and limited mobility. Common treatment options are total knee replacement and lateral unicompartmental knee arthroplasty (UKA). The domed lateral mobile-bearing Oxford Uni is a new treatment option for patients with isolated osteoarthritis of the lateral compartment of the knee joint. We used instrumented gait analysis and clinical scores to study patients before and after lateral UKA. Methods Nineteen patients suffering from lateral osteoarthritis underwent implantation of a mobile-bearing lateral UKA. They were examined in a gait analysis before the operation and after an average follow-up time of 7 months. Gait analysis was performed on a treadmill with six
infrared cameras to identify gait characteristics (e.g. velocity, stride time, stride length, knee abduction or hip adduction). Results Mean velocity changed from 0.58 to 0.73 m/s. Significant advancements were also found in knee abduction and hip adduction. Time and length of strides improved significantly as well as the clinical scores American Knee Society Score, Oxford-12, FFb-H-OA and Devane Score. Conclusion Patients with lateral osteoarthritis of the knee showed an impaired gait with an increased knee abduction and hip adduction angle. Implantation of a lateral mobile UKA can restore normal axis of the leg and improve gait and function of the knee. Instrumented gait analysis is a suitable measuring instrument to quantify and qualify the post-operative change of gait. Level of evidence II.
J. B. Seeger (&) G. S. Maier Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstraße 33, 35392 Giessen, Germany e-mail: [email protected]; [email protected]
Keywords Unicompartmental knee Lateral bearing Osteoarthritis Gait analysis Gait pattern
J. P. Schikschneit S. Ja¨ger Department of Orthopaedics, Traumatology and Paraplegiology, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany C. Schuld R. Rupp Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany H. Schmitt ATOS Klinik Heidelberg, Bismarckstraße 9-15, 69115 Heidelberg, Germany M. Clarius Department of Orthopaedic and Trauma Surgery, Vulpius Klinik GmbH, Vulpiusstraße 29, 74906 Bad Rappenau, Germany
Introduction Osteoarthritis of the knee joint is a well-known and common disease [9, 23] generally located in the medial compartment of the knee joint. Excellent clinical outcomes for medial unicompartmental knee arthroplasty (UKA) have been reported [2, 21, 26]. It is less invasive than total knee arthroplasty (TKA), preserving the cruciate ligaments and providing a better range of motion and more physiological function [2, 25]. Further advantages of this prosthesis are less blood loss, fewer complications, faster rehabilitation and less cost compared to TKA [37]. Tibiofemoral knee osteoarthritis is nine times more common in the medial than in the lateral compartment [10].
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Knee Surg Sports Traumatol Arthrosc
Genu valgus alignment is often associated with proximal hip adduction and distal rear-foot eversion [13], increasing the risk of lateral joint space narrowing by 62 % and lateral osteophytes by 13 % [35]. Biomechanical studies show that varus and valgus alignment increase medial and lateral load, respectively [19]. It is these increases in joint space narrowing and compartment loading that are thought to increase stress on articular cartilage and other joint structures, subsequently leading to degenerative changes [34]. Whereas medial mobile-bearing Oxford UKA is a successful treatment option for patients with medial osteoarthritis of the knee, the initial results of lateral mobilebearing UKA have been less encouraging [28] with dislocation rates of 10 % of the bearing within the first year [14]. This dislocation rate problem has been analysed [31] and addressed by a new surgical technique and a newly designed spherically convex domed tibial component. The redesigned lateral component of the Oxford mobilebearing Uni has a spherically convex, domed tibial component and a biconcave bearing that ensures congruent contact between the components throughout flexion and increased entrapment (7 mm) [33]. The group that developed it demonstrated a reduced 4-year dislocation rate (11–1.7 %) with the new Oxford lateral UKA [24]. Gait analysis provides an objective measure of a patient’s functioning following total knee replacement with a particularly accurate measurement of sagittal plane kinematics and kinetics [18]. Gait analyses are described in patients with opening wedge high tibial osteotomy [6], UKA [5], TKA [11], limb-preserving surgery [27] as well as patients with paraplegia or cerebral palsy [1, 8]. Self-selected walking speed, single limb support and step length have been shown to increase after unicompartmental arthroplasty [5, 17, 36]. The aim of this study was to evaluate standardized instrumented gait analysis for functional recovery and gait as an outcome of lateral UKA in patients with lateral osteoarthritis of the knee. It was hypothesized that patients with lateral knee osteoarthritis present a characteristic gait pattern with increased hip adduction and knee abduction. It was expected that after lateral UKA, these parameters would change accordingly.
women and nine men. Twelve right knees and seven left knees were analysed. All operations were performed at the same institution by two experienced knee surgeons (MC and PRA). All patients suffered from valgus osteoarthritis (except one Morbus Ahlbeck), and all had previously undergone a lateral meniscectomy. Assessments The following clinical scores were assessed: • • • • •
American Knee Society Score (AKSS) [16] Oxford-12 Score [22] Devane Score [7] FFbH-OA Score (Hannover Functional Ability Questionnaire for Osteoarthritis) [15] Numeric rating scale (NRS) [32]
Kinematics of each patient were examined on a custom treadmill before and after [with a median of 7.2 (5–8) months] implantation of UKA. The static Helen Hayes marker set with 32 markers attached to anatomic landmarks was used for gait analytical assessment. Six infrared cameras (Eagle, Motional Analysis, Santa Rosa, CA) recorded movements of the reflective markers with a sampling frequency of 60 Hz [38]. Study protocol Gait analysis was performed three times under standardized conditions for a total of 90 s at a slow, normal and fast velocity. The patient’s self-selected comfortable walking speed on the treadmill rounded to the next step of 0.2 m/s was set as ‘‘normal’’ walking speed. Slow walking speed was calculated as normal speed minus 0.2 m/s and fast walking speed as normal speed plus 0.2 m/s. The same setup was chosen for the post-operative measurement [1]. Additionally, a standardized trial with a gait speed of 0.4 m/s was performed with all patients. This speed was identified as the fastest speed possible for all patients in the preoperative measurement. A common gait velocity in a pre-/post-set-up is desirable, because gait kinematics is largely [30] a function of gait speed. Post-processing
Materials and methods Twenty consecutive UKAs in twenty patients using the Oxford domed lateral component (Biomet UK Ltd, Swindon, UK) were enrolled in this study. One patient died a few days after surgery with an unknown cause of death. No patients were lost to follow-up. Patients were between 39 and 78 years old with an average age of 60 years (±10 years). Ten of them were
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Measurements were recorded and post-processed (correcting marker assignment, filling gaps, no filtering) in EVaRT 5.0.3 (Motion Analysis Inc.; Santa Rosa, CA). OrthoTrak Motion Analysis 624 (Motion Analysis Inc., Santa Rosa, CA) was used to calculate jointed angles of the lower extremities for each trial. A custom database [29] was used to create a data set for the open-source data-mining tool Gait-CAD (v3.3; http://sourceforge.net/projects/gait-cad/) [36] where all subsequent analysis tasks were performed.
Knee Surg Sports Traumatol Arthrosc
For each trial, averaged joint angles were calculated referenced to 100 % gait cycle. One outlier had to be eliminated to prevent distortion of the results for the reason of missing data, so that 18 valid profiles were evaluated. Pre- and post-operative gait parameters were compared to analyse gait improvements of the operated leg. The study protocol was approved by the institutional university review board and accepted by the local ethics committee of the university of Heidelberg (number of approval: S-117/2008). Statistical analysis Statistical analysis was performed using SPSS version 16.0 for Windows (SPSS Inc., Chicago, Illinois) and the nonparametric Wilcoxon’s test. The tests were two-sided, and a p value of \0.05 was considered significant. With a statistical power of 80 % and an alpha of 5 %, the sample size was 18 for the nonparametric Wilcoxon’s test.
Results Preoperatively patients with lateral osteoarthritis of the knee presented a characteristic gait pattern with increased
hip adduction and knee abduction. These parameters have been analysed in all patients (Fig. 1). After surgical treatment, hip adduction, knee abduction (MEAN Stride) as well as stride time and stride length showed significant changes (Table 1). The curves displayed similar motion as the healthy leg, due to the changes of joint angles and gait pattern of the operated extremity, and the prosthesis leg curve approached the healthy one (Fig. 2). The motion of the healthy leg also increased due to rebalancing of the formerly restricted leg. The degree of knee abduction also shifted by 5.4 from -6.5 preoperative to -1.1 post-operative (p = 0.014). The degree of hip adduction went from 4.6 before the operation to 1.2 with a p value of 0.013. The stride length rose from 71.8 to 76.3 cm (p = 0.045). Likewise, the stride time increased significantly from 1.3 to 1.5 s (p = 0.047). All values were evaluated under the predetermined velocity of 0.56 m/s. The patient’s self-selected walking speed changed from 0.58 to 0.73 m/s (p \ 0.05). By comparing the preoperative to both post-operative speed measurements, an increase from 0.51 to 0.63 m/s after 7.4 months was observed. Pain reduced from 6.6 to 1.2 (p \ 0.05) on the numeric rating scale. Patients were very satisfied post-operatively with an average value of 1.9 (from 1 for extremely satisfied
Fig. 1 Evaluation of a patient, preoperative versus 7 months post-operative
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to 5 for unsatisfied). AKSS increased significantly from 72.8 to 92.5 in function and from 47.9 to 91.6 in motion. The Oxford-12 Score changed from 28.9 to 17.8 postoperatively. The Devane activity score changed from 2.7 (±0.66) to 3.9 (±0.31). The FFbH-OA changed from 74.3 (±19.4) to 92.1 (±9.2). All clinical scores AKSS, OxfordTable 1 Parameters before (PRE) and after (POST 7) implantation of the lateral UKA Evaluation programme: GAITCAD (n = 19)
PRE (mean ± SD)
POST 7.2 (mean ± SD)
p values
-1.1 ± 6.3
0.014 0.013
Prosthesis leg Determinated velocity (m/s)
0.56 = 0.56
Knee adduction () (negative = abduction)
-6.5 ± 5.8
Hip adduction () (negative = abduction)
4.6 ± 4.2
1.2 ± 2.6
Cadence (strides/min)
46.0 ± 5.0
42.7 ± 7.1
n.s.
Stride time (s) Stride length (cm)
1.3 ± 0.1 71.8 ± 21.3
1.5 ± 0.3 76.3 ± 18.3
0.047 0.045
-2.0 ± 6.4
n.s.
Healthy leg Determinated velocity (m/s)
0.56 = 0.56
Knee adduction () (negative = abduction)
-2.2 ± 4.5
Hip adduction ()
1.2 ± 5.1
1.8 ± 4.6
n.s.
Cadence (strides/min)
46.0 ± 5.0
42.7 ± 7.1
n.s.
Stride time (s) Stride length (cm)
1.3 ± 0.2 72.0 ± 20.3
1.5 ± 0.3 75.3 ± 19.0
n.s. n.s.
Fig. 2 Gait curves of all patients in average
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12, Devane and FFbH-OA showed significant changes (p \ 0.05).
Discussion The most important finding of the present study was the change of hip adduction and knee abduction in patients before and after lateral UKA. One hypothesis was that patients with lateral knee osteoarthritis present a characteristic gait pattern with increased hip adduction and knee abduction. Butler et al. [4] state that the direction of knee malalignment (varus or valgus) influences which knee compartment becomes involved and probably influences gait mechanics. Genu valgus alignment is often associated with hip adduction proximally and rear-foot eversion distally [13]. The results suggest that people with lateral knee osteoarthritis exhibit typical gait mechanics with increased hip adduction and knee abduction based on the osseous defect in the femur and the lateral tibial plateau. Instrumented gait analysis enables the physician to document time–distance parameters, joint kinematics and kinetics. It is used not just for diagnostic purposes but also to monitor the effects of surgical treatments [8]. Webster et al. [36] identified that patients were able to increase their walking speed by 28 % by increasing both stride length and cadence. In the present study, the stride length rose (from 71.8 to 76.3 cm), but the cadence decreased from 46.0 to 42.7 strides/min (n.s.).
Knee Surg Sports Traumatol Arthrosc
Fuchs et al. [12] examined the gait in patients who received a fixed-bearing UKA and pointed out that UKA has failed to restore functional capabilities, quality of life, gait pattern and muscle activity compared with healthy subjects of the same age [12]. In the present study, the gait parameters hip adduction and knee abduction improved significantly, and joint angles were corrected and approached the healthy leg. Furthermore, clinical scores improved significantly, and all patients could get back to an active daily life after surgery. Catani et al. [5] presented a mean Knee Society Score postoperatively of 94.1 ± 9.5. This result is similar to the score of 92.50 in function and 91.55 in motion. Treatment of isolated osteoarthritis of the lateral compartment still remains challenging, and dislocation is an issue when lateral UKA is used. Initial results of lateral UKA reported a rate of dislocation of 11 % at 3 years and an estimated 3-year survival using revision as the endpoint at 82 % [14]. This study was based on six revisions of 53 knee joints treated with UKA for lateral osteoarthritis. Streit et al. [33] depict several reasons for dislocation such as subluxation of the lateral femoral condyle in deep flexion and an elevation of the lateral joint line. The study also has limitations. In gait analysis studies, uncontrollable influences may play an important role and substantial methodologic differences between studies may contribute to inconsistencies in reported findings for many gait outcomes [18]. In the present study, patients were requested to perform gait analysis without the use of handles. However, for security reasons and to prevent patients from stumbling or falling, handles had to be installed. This study demonstrates that the clinical effect of UKA is an outcome of the prosthesis design in combination with the surgical technique. Implantation of UKA enables a prolonged functioning of the knee by saving proprioception, ligaments and bone [3]. Instrumented gait analysis, especially for younger patients with lateral osteoarthritis of the knee joint, helps surgeons, patients and physiotherapists in their decisionmaking. Gait deficiencies are elaborated in those patients, and surgeons can decide about the appropriate treatment methods for their patients [20].
Conclusion Patients with isolated osteoarthritis of the lateral compartment of the knee joint present a typical gait pattern with increased hip adduction and knee abduction based on the osseous defect in the femur and the lateral tibial plateau. Instrumented gait analysis shows an approximation of the gait pattern to the healthy leg, particularly in the two parameters knee abduction and hip adduction. Gait analysis
is a suitable measuring instrument to quantify and qualify the change of gait following implantation of the domed lateral UKA. Acknowledgments The authors thank the Orthopa¨dische Universita¨tsklinik Heidelberg for the financial support and the equipment, as well as J. Schweidler and M. Kru¨ger for their technical assistance in data acquisition.
References 1. Abel R, Schablowski M, Rupp R, Gerner HJ (2002) Gait analysis on the treadmill-monitoring exercise in the treatment of paraplegia. Spinal Cord 40(1):17–22 2. Aldinger PR, Clarius M, Murray DW, Goodfellow JW, Breusch SJ (2004) Medial unicompartmental knee replacement using the ‘‘Oxford Uni’’ meniscal bearing knee. Orthopade 33(11): 1277–1283 3. Berger RA, Nedeff DD, Barden RM, Sheinkop MM, Jacobs JJ, Rosenberg AG, Galante JO (1999) Unicompartmental knee arthroplasty. Clinical experience at 6- to 10-year followup. Clin Orthop Relat Res 367:50–60 4. Butler RJ, Barrios JA, Royer T, Davis IS (2011) Frontal-plane gait mechanics in people with medial knee osteoarthritis are different from those in people with lateral knee osteoarthritis. Phys Ther 91(8):1235–1243 5. Catani F, Benedetti MG, Bianchi L, Marchionni V, Giannini S, Leardini A (2012) Muscle activity around the knee and gait performance in unicompartmental knee arthroplasty patients: a comparative study on fixed- and mobile-bearing designs. Knee Surg Sports Traumatol Arthrosc 20(6):1042–1048 6. Collins B, Getgood A, Alomar AZ, Giffin JR, Willits K, Fowler PJ, Birmingham TB, Litchfield RB (2013) A case series of lateral opening wedge high tibial osteotomy for valgus malalignment. Knee Surg Sports Traumatol Arthrosc 21(1):152–160 7. Devane PA, Horne JG, Martin K, Coldham G, Krause B (1997) Three-dimensional polyethylene wear of a press-fit titanium prosthesis. Factors influencing generation of polyethylene debris. J Arthroplast 12(3):256–266 8. Doderlein L, Wolf S (2004) The value of instrumented gait analysis in infantile cerebral palsy. Orthopade 33(10):1103–1118 9. Felson DT (1988) Epidemiology of hip and knee osteoarthritis. Epidemiol Rev 10:1–28 10. Felson DT, Nevitt MC, Zhang Y, Aliabadi P, Baumer B, Gale D, Li W, Yu W, Xu L (2002) High prevalence of lateral knee osteoarthritis in Beijing Chinese compared with Framingham Caucasian subjects. Arthritis Rheum 46(5):1217–1222 11. Fuchs S, Floren M, Skwara A, Tibesku CO (2002) Quantitative gait analysis in unconstrained total knee arthroplasty patients. Int J Rehabil Res 25(1):65–70 12. Fuchs S, Tibesku CO, Frisse D, Laass H, Rosenbaum D (2003) Quality of life and gait after unicondylar knee prosthesis are inferior to age-matched control subjects. Am J Phys Med Rehabil 82(6):441–446 13. Gross MT (1995) Lower quarter screening for skeletal malalignment—suggestions for orthotics and shoewear. J Orthop Sports Phys Ther 21(6):389–405 14. Gunther TV, Murray DW, Miller R, Wallace DA, Carr AJ, O’Connor JJ, McLardy-Smith P, Goodfellow JW (1996) Lateral unicompartmental arthroplasty with the Oxford meniscal knee. Knee 3(1–2):33–39 15. Haase I, Schwarz A, Burger A, Kladny B (2001) Comparison of Hannover Functional Ability Questionnaire (FFbH) and the SF36 subscale ‘‘Physical Functioning’’. Rehabilitation 40(1):40–42
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Knee Surg Sports Traumatol Arthrosc 16. Insall JN, Dorr LD, Scott RD, Scott WN (1989) Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res 248:13–14 17. Mattsson E, Brostrom LA, Linnarsson D (1990) Changes in walking ability after knee replacement. Int Orthop 14(3):277–280 18. McClelland JA, Webster KE, Feller JA (2007) Gait analysis of patients following total knee replacement: a systematic review. Knee 14(4):253–263 19. McKellop HA, Llinas A, Sarmiento A (1994) Effects of tibial malalignment on the knee and ankle. Orthop Clin North Am 25(3):415–423 20. Minns RJ (2005) The role of gait analysis in the management of the knee. Knee 12(3):157–162 21. Murray DW, Goodfellow JW, O’Connor JJ (1998) The Oxford medial unicompartmental arthroplasty: a ten-year survival study. J Bone Jt Surg Br 80(6):983–989 22. Naal FD, Impellizzeri FM, Sieverding M, Loibl M, von Knoch F, Mannion AF, Leunig M, Munzinger U (2009) The 12-item Oxford Knee Score: cross-cultural adaptation into German and assessment of its psychometric properties in patients with osteoarthritis of the knee. Osteoarthr Cartil 17(1):49–52 23. Oliveria SA, Felson DT, Reed JI, Cirillo PA, Walker AM (1995) Incidence of symptomatic hand, hip, and knee osteoarthritis among patients in a health maintenance organization. Arthritis Rheum 38(8):1134–1141 24. Pandit H, Jenkins C, Beard DJ, Price AJ, Gill HS, Dodd CA, Murray DW (2010) Mobile bearing dislocation in lateral unicompartmental knee replacement. Knee 17(6):392–397 25. Price AJ, Webb J, Topf H, Dodd CA, Goodfellow JW, Murray DW (2001) Rapid recovery after oxford unicompartmental arthroplasty through a short incision. J Arthroplast 16(8):970–976 26. Price AJWJ, Svard U (2005) Long-term clinical results of the medial Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res 435:171–180 27. Rompen JC, Ham SJ, Halbertsma JP, van Horn JR (2002) Gait and function in patients with a femoral endoprosthesis after tumor resection: 18 patients evaluated 12 years after surgery. Acta Orthop Scand 73(4):439–446 28. Saxler G, Temmen D, Bontemps G (2004) Medium-term results of the AMC-unicompartmental knee arthroplasty. Knee 11(5): 349–355
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29. Schablowski M, Schweidler J, Rupp R (2004) HeiDATAProVITHeidelberg data archiving, tag assembling, processing and visualization tool. Comput Methods Progr Biomed 73(1):61–70 30. Schablowski-Trautmann M (2005) Konzept zur analyse der Lokolotion auf dem Laufband bei inkompletter Querschnittla¨hmung mit Verfahren der nichtlinearen Dynamik. Unitversita¨t Karlsruhe (TH), Karlsruhe 31. Schelfaut S, Beckers L, Verdonk P, Bellemans J, Victor J (2013) The risk of bearing dislocation in lateral unicompartmental knee arthroplasty using a mobile biconcave design. Knee Surg Sports Traumatol Arthrosc 21(11):2487–2494 32. Snijders GF, den Broeder AA, van Riel PL, Straten VH, de Man FH, van den Hoogen FH, van den Ende CH (2011) Evidencebased tailored conservative treatment of knee and hip osteoarthritis: between knowing and doing. Scand J Rheumatol 40(3):225–231 33. Streit MR, Walker T, Bruckner T, Merle C, Kretzer JP, Clarius M, Aldinger PR, Gotterbarm T (2012) Mobile-bearing lateral unicompartmental knee replacement with the Oxford domed tibial component: an independent series. J Bone Jt Surg Br 94(10):1356–1361 34. Tanamas S, Hanna FS, Cicuttini FM, Wluka AE, Berry P, Urquhart DM (2009) Does knee malalignment increase the risk of development and progression of knee osteoarthritis? A systematic review. Arthritis Rheum 61(4):459–467 35. Teichtahl AJ, Cicuttini FM, Janakiramanan N, Davis SR, Wluka AE (2006) Static knee alignment and its association with radiographic knee osteoarthritis. Osteoarthr Cartil 14(9):958–962 36. Webster KE, Wittwer JE, Feller JA (2003) Quantitative gait analysis after medial unicompartmental knee arthroplasty for osteoarthritis. J Arthroplast 18(6):751–759 37. Willis-Owen CA, Brust K, Alsop H, Miraldo M, Cobb JP (2009) Unicondylar knee arthroplasty in the UK National Health Service: an analysis of candidacy, outcome and cost efficacy. Knee 16(6):473–478 38. Wolf S, Loose T, Schablowski M, Doderlein L, Rupp R, Gerner HJ, Bretthauer G, Mikut R (2006) Automated feature assessment in instrumented gait analysis. Gait Posture 23(3):331–338
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Change of gait in patients with lateral osteoarthritis of the knee after mobile-bearing unicompartmental knee arthroplasty J. B. Seeger • J. P. Schikschneit • C. Schuld • R. Rupp • S. Ja¨ger • H. Schmitt • G. S. Maier M. Clarius
•
Received: 20 August 2013 / Accepted: 10 March 2014 Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Patients with lateral osteoarthritis of the knee suffer not only from pain but also impaired gait and limited mobility. Common treatment options are total knee replacement and lateral unicompartmental knee arthroplasty (UKA). The domed lateral mobile-bearing Oxford Uni is a new treatment option for patients with isolated osteoarthritis of the lateral compartment of the knee joint. We used instrumented gait analysis and clinical scores to study patients before and after lateral UKA. Methods Nineteen patients suffering from lateral osteoarthritis underwent implantation of a mobile-bearing lateral UKA. They were examined in a gait analysis before the operation and after an average follow-up time of 7 months. Gait analysis was performed on a treadmill with six
infrared cameras to identify gait characteristics (e.g. velocity, stride time, stride length, knee abduction or hip adduction). Results Mean velocity changed from 0.58 to 0.73 m/s. Significant advancements were also found in knee abduction and hip adduction. Time and length of strides improved significantly as well as the clinical scores American Knee Society Score, Oxford-12, FFb-H-OA and Devane Score. Conclusion Patients with lateral osteoarthritis of the knee showed an impaired gait with an increased knee abduction and hip adduction angle. Implantation of a lateral mobile UKA can restore normal axis of the leg and improve gait and function of the knee. Instrumented gait analysis is a suitable measuring instrument to quantify and qualify the post-operative change of gait. Level of evidence II.
J. B. Seeger (&) G. S. Maier Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstraße 33, 35392 Giessen, Germany e-mail: [email protected]; [email protected]
Keywords Unicompartmental knee Lateral bearing Osteoarthritis Gait analysis Gait pattern
J. P. Schikschneit S. Ja¨ger Department of Orthopaedics, Traumatology and Paraplegiology, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany C. Schuld R. Rupp Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany H. Schmitt ATOS Klinik Heidelberg, Bismarckstraße 9-15, 69115 Heidelberg, Germany M. Clarius Department of Orthopaedic and Trauma Surgery, Vulpius Klinik GmbH, Vulpiusstraße 29, 74906 Bad Rappenau, Germany
Introduction Osteoarthritis of the knee joint is a well-known and common disease [9, 23] generally located in the medial compartment of the knee joint. Excellent clinical outcomes for medial unicompartmental knee arthroplasty (UKA) have been reported [2, 21, 26]. It is less invasive than total knee arthroplasty (TKA), preserving the cruciate ligaments and providing a better range of motion and more physiological function [2, 25]. Further advantages of this prosthesis are less blood loss, fewer complications, faster rehabilitation and less cost compared to TKA [37]. Tibiofemoral knee osteoarthritis is nine times more common in the medial than in the lateral compartment [10].
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Knee Surg Sports Traumatol Arthrosc
Genu valgus alignment is often associated with proximal hip adduction and distal rear-foot eversion [13], increasing the risk of lateral joint space narrowing by 62 % and lateral osteophytes by 13 % [35]. Biomechanical studies show that varus and valgus alignment increase medial and lateral load, respectively [19]. It is these increases in joint space narrowing and compartment loading that are thought to increase stress on articular cartilage and other joint structures, subsequently leading to degenerative changes [34]. Whereas medial mobile-bearing Oxford UKA is a successful treatment option for patients with medial osteoarthritis of the knee, the initial results of lateral mobilebearing UKA have been less encouraging [28] with dislocation rates of 10 % of the bearing within the first year [14]. This dislocation rate problem has been analysed [31] and addressed by a new surgical technique and a newly designed spherically convex domed tibial component. The redesigned lateral component of the Oxford mobilebearing Uni has a spherically convex, domed tibial component and a biconcave bearing that ensures congruent contact between the components throughout flexion and increased entrapment (7 mm) [33]. The group that developed it demonstrated a reduced 4-year dislocation rate (11–1.7 %) with the new Oxford lateral UKA [24]. Gait analysis provides an objective measure of a patient’s functioning following total knee replacement with a particularly accurate measurement of sagittal plane kinematics and kinetics [18]. Gait analyses are described in patients with opening wedge high tibial osteotomy [6], UKA [5], TKA [11], limb-preserving surgery [27] as well as patients with paraplegia or cerebral palsy [1, 8]. Self-selected walking speed, single limb support and step length have been shown to increase after unicompartmental arthroplasty [5, 17, 36]. The aim of this study was to evaluate standardized instrumented gait analysis for functional recovery and gait as an outcome of lateral UKA in patients with lateral osteoarthritis of the knee. It was hypothesized that patients with lateral knee osteoarthritis present a characteristic gait pattern with increased hip adduction and knee abduction. It was expected that after lateral UKA, these parameters would change accordingly.
women and nine men. Twelve right knees and seven left knees were analysed. All operations were performed at the same institution by two experienced knee surgeons (MC and PRA). All patients suffered from valgus osteoarthritis (except one Morbus Ahlbeck), and all had previously undergone a lateral meniscectomy. Assessments The following clinical scores were assessed: • • • • •
American Knee Society Score (AKSS) [16] Oxford-12 Score [22] Devane Score [7] FFbH-OA Score (Hannover Functional Ability Questionnaire for Osteoarthritis) [15] Numeric rating scale (NRS) [32]
Kinematics of each patient were examined on a custom treadmill before and after [with a median of 7.2 (5–8) months] implantation of UKA. The static Helen Hayes marker set with 32 markers attached to anatomic landmarks was used for gait analytical assessment. Six infrared cameras (Eagle, Motional Analysis, Santa Rosa, CA) recorded movements of the reflective markers with a sampling frequency of 60 Hz [38]. Study protocol Gait analysis was performed three times under standardized conditions for a total of 90 s at a slow, normal and fast velocity. The patient’s self-selected comfortable walking speed on the treadmill rounded to the next step of 0.2 m/s was set as ‘‘normal’’ walking speed. Slow walking speed was calculated as normal speed minus 0.2 m/s and fast walking speed as normal speed plus 0.2 m/s. The same setup was chosen for the post-operative measurement [1]. Additionally, a standardized trial with a gait speed of 0.4 m/s was performed with all patients. This speed was identified as the fastest speed possible for all patients in the preoperative measurement. A common gait velocity in a pre-/post-set-up is desirable, because gait kinematics is largely [30] a function of gait speed. Post-processing
Materials and methods Twenty consecutive UKAs in twenty patients using the Oxford domed lateral component (Biomet UK Ltd, Swindon, UK) were enrolled in this study. One patient died a few days after surgery with an unknown cause of death. No patients were lost to follow-up. Patients were between 39 and 78 years old with an average age of 60 years (±10 years). Ten of them were
123
Measurements were recorded and post-processed (correcting marker assignment, filling gaps, no filtering) in EVaRT 5.0.3 (Motion Analysis Inc.; Santa Rosa, CA). OrthoTrak Motion Analysis 624 (Motion Analysis Inc., Santa Rosa, CA) was used to calculate jointed angles of the lower extremities for each trial. A custom database [29] was used to create a data set for the open-source data-mining tool Gait-CAD (v3.3; http://sourceforge.net/projects/gait-cad/) [36] where all subsequent analysis tasks were performed.
Knee Surg Sports Traumatol Arthrosc
For each trial, averaged joint angles were calculated referenced to 100 % gait cycle. One outlier had to be eliminated to prevent distortion of the results for the reason of missing data, so that 18 valid profiles were evaluated. Pre- and post-operative gait parameters were compared to analyse gait improvements of the operated leg. The study protocol was approved by the institutional university review board and accepted by the local ethics committee of the university of Heidelberg (number of approval: S-117/2008). Statistical analysis Statistical analysis was performed using SPSS version 16.0 for Windows (SPSS Inc., Chicago, Illinois) and the nonparametric Wilcoxon’s test. The tests were two-sided, and a p value of \0.05 was considered significant. With a statistical power of 80 % and an alpha of 5 %, the sample size was 18 for the nonparametric Wilcoxon’s test.
Results Preoperatively patients with lateral osteoarthritis of the knee presented a characteristic gait pattern with increased
hip adduction and knee abduction. These parameters have been analysed in all patients (Fig. 1). After surgical treatment, hip adduction, knee abduction (MEAN Stride) as well as stride time and stride length showed significant changes (Table 1). The curves displayed similar motion as the healthy leg, due to the changes of joint angles and gait pattern of the operated extremity, and the prosthesis leg curve approached the healthy one (Fig. 2). The motion of the healthy leg also increased due to rebalancing of the formerly restricted leg. The degree of knee abduction also shifted by 5.4 from -6.5 preoperative to -1.1 post-operative (p = 0.014). The degree of hip adduction went from 4.6 before the operation to 1.2 with a p value of 0.013. The stride length rose from 71.8 to 76.3 cm (p = 0.045). Likewise, the stride time increased significantly from 1.3 to 1.5 s (p = 0.047). All values were evaluated under the predetermined velocity of 0.56 m/s. The patient’s self-selected walking speed changed from 0.58 to 0.73 m/s (p \ 0.05). By comparing the preoperative to both post-operative speed measurements, an increase from 0.51 to 0.63 m/s after 7.4 months was observed. Pain reduced from 6.6 to 1.2 (p \ 0.05) on the numeric rating scale. Patients were very satisfied post-operatively with an average value of 1.9 (from 1 for extremely satisfied
Fig. 1 Evaluation of a patient, preoperative versus 7 months post-operative
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Knee Surg Sports Traumatol Arthrosc
to 5 for unsatisfied). AKSS increased significantly from 72.8 to 92.5 in function and from 47.9 to 91.6 in motion. The Oxford-12 Score changed from 28.9 to 17.8 postoperatively. The Devane activity score changed from 2.7 (±0.66) to 3.9 (±0.31). The FFbH-OA changed from 74.3 (±19.4) to 92.1 (±9.2). All clinical scores AKSS, OxfordTable 1 Parameters before (PRE) and after (POST 7) implantation of the lateral UKA Evaluation programme: GAITCAD (n = 19)
PRE (mean ± SD)
POST 7.2 (mean ± SD)
p values
-1.1 ± 6.3
0.014 0.013
Prosthesis leg Determinated velocity (m/s)
0.56 = 0.56
Knee adduction () (negative = abduction)
-6.5 ± 5.8
Hip adduction () (negative = abduction)
4.6 ± 4.2
1.2 ± 2.6
Cadence (strides/min)
46.0 ± 5.0
42.7 ± 7.1
n.s.
Stride time (s) Stride length (cm)
1.3 ± 0.1 71.8 ± 21.3
1.5 ± 0.3 76.3 ± 18.3
0.047 0.045
-2.0 ± 6.4
n.s.
Healthy leg Determinated velocity (m/s)
0.56 = 0.56
Knee adduction () (negative = abduction)
-2.2 ± 4.5
Hip adduction ()
1.2 ± 5.1
1.8 ± 4.6
n.s.
Cadence (strides/min)
46.0 ± 5.0
42.7 ± 7.1
n.s.
Stride time (s) Stride length (cm)
1.3 ± 0.2 72.0 ± 20.3
1.5 ± 0.3 75.3 ± 19.0
n.s. n.s.
Fig. 2 Gait curves of all patients in average
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12, Devane and FFbH-OA showed significant changes (p \ 0.05).
Discussion The most important finding of the present study was the change of hip adduction and knee abduction in patients before and after lateral UKA. One hypothesis was that patients with lateral knee osteoarthritis present a characteristic gait pattern with increased hip adduction and knee abduction. Butler et al. [4] state that the direction of knee malalignment (varus or valgus) influences which knee compartment becomes involved and probably influences gait mechanics. Genu valgus alignment is often associated with hip adduction proximally and rear-foot eversion distally [13]. The results suggest that people with lateral knee osteoarthritis exhibit typical gait mechanics with increased hip adduction and knee abduction based on the osseous defect in the femur and the lateral tibial plateau. Instrumented gait analysis enables the physician to document time–distance parameters, joint kinematics and kinetics. It is used not just for diagnostic purposes but also to monitor the effects of surgical treatments [8]. Webster et al. [36] identified that patients were able to increase their walking speed by 28 % by increasing both stride length and cadence. In the present study, the stride length rose (from 71.8 to 76.3 cm), but the cadence decreased from 46.0 to 42.7 strides/min (n.s.).
Knee Surg Sports Traumatol Arthrosc
Fuchs et al. [12] examined the gait in patients who received a fixed-bearing UKA and pointed out that UKA has failed to restore functional capabilities, quality of life, gait pattern and muscle activity compared with healthy subjects of the same age [12]. In the present study, the gait parameters hip adduction and knee abduction improved significantly, and joint angles were corrected and approached the healthy leg. Furthermore, clinical scores improved significantly, and all patients could get back to an active daily life after surgery. Catani et al. [5] presented a mean Knee Society Score postoperatively of 94.1 ± 9.5. This result is similar to the score of 92.50 in function and 91.55 in motion. Treatment of isolated osteoarthritis of the lateral compartment still remains challenging, and dislocation is an issue when lateral UKA is used. Initial results of lateral UKA reported a rate of dislocation of 11 % at 3 years and an estimated 3-year survival using revision as the endpoint at 82 % [14]. This study was based on six revisions of 53 knee joints treated with UKA for lateral osteoarthritis. Streit et al. [33] depict several reasons for dislocation such as subluxation of the lateral femoral condyle in deep flexion and an elevation of the lateral joint line. The study also has limitations. In gait analysis studies, uncontrollable influences may play an important role and substantial methodologic differences between studies may contribute to inconsistencies in reported findings for many gait outcomes [18]. In the present study, patients were requested to perform gait analysis without the use of handles. However, for security reasons and to prevent patients from stumbling or falling, handles had to be installed. This study demonstrates that the clinical effect of UKA is an outcome of the prosthesis design in combination with the surgical technique. Implantation of UKA enables a prolonged functioning of the knee by saving proprioception, ligaments and bone [3]. Instrumented gait analysis, especially for younger patients with lateral osteoarthritis of the knee joint, helps surgeons, patients and physiotherapists in their decisionmaking. Gait deficiencies are elaborated in those patients, and surgeons can decide about the appropriate treatment methods for their patients [20].
Conclusion Patients with isolated osteoarthritis of the lateral compartment of the knee joint present a typical gait pattern with increased hip adduction and knee abduction based on the osseous defect in the femur and the lateral tibial plateau. Instrumented gait analysis shows an approximation of the gait pattern to the healthy leg, particularly in the two parameters knee abduction and hip adduction. Gait analysis
is a suitable measuring instrument to quantify and qualify the change of gait following implantation of the domed lateral UKA. Acknowledgments The authors thank the Orthopa¨dische Universita¨tsklinik Heidelberg for the financial support and the equipment, as well as J. Schweidler and M. Kru¨ger for their technical assistance in data acquisition.
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