Flexion Contracture Following Primary Total Knee Arthroplasty: Risk Factors and Outcomes

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1 Feture Article Flexion Contrcture Following Primry Totl Knee Arthroplsty: Risk Fctors nd Outcomes STUART T. GOUDIE, MBCHB; ANGELA H. DEAKIN, PHD; AFTAB AHMAD, FRCS; ROHIT MAHESHWARI, MS, FRCS; FREDERIC PICARD, MD bstrct Full rticle vilble online t ORTHOSuperSite.com. Serch: Function nd stisfction fter totl knee rthroplsty (TKA) re prtilly linked to postopertive rnge of motion (ROM). Fixed flexion contrcture is recognized compliction of TKA tht reduces ROM nd is source of morbidity for ptients. This study imed to identify preopertive risk fctors for developing fixed flexion contrcture following TKA nd to quntify the effect of fixed flexion contrcture on outcomes (Oxford knee score nd ptient stisfction) t 2 yers. Pre-, intr-, nd postopertive dt for 811 TKAs were retrospectively reviewed. At 2 yers postopertively, the incidence of fixed flexion contrcture ws 3.6%. Men were 2.6 times more likely thn women to hve fixed flexion contrcture (P=.012), nd ptients with preimplnt fixed flexion contrcture were 2.3 times more likely thn those without to hve fixed flexion contrcture (P=.028). Incresing ge ws ssocited with n incresed rte of fixed flexion contrcture (P=.02). Body mss index ws not risk fctor (P=.968). Incidence of fixed flexion contrcture for those undergoing computer nvigted TKA ws 3.9% compred with 3.4% for those hving conventionl surgery (P=.711). Ptients with fixed flexion contrcture hd poorer outcomes with medin [interqurtile rnge] Oxford Knee Score of 25 [15] compred with 20 [11] for those without (P=.003) nd lower ptient stisfction (P=.036). These results support existing literture for incidence of fixed flexion contrcture fter TKA, risk fctors, nd outcomes, indicting tht these figures cn be extrpolted to wide popultion. They lso clrify previously contentious point by excluding body mss index s risk fctor. Messrs Goudie, Ahmd, nd Mheshwri nd Drs Dekin nd Picrd re from the Deprtment of Orthopedics, Golden Jubilee Ntionl Hospitl, Clydebnk, Scotlnd, United Kingdom. Messrs Goudie, Ahmd, nd Mheshwri nd Drs Dekin nd Picrd hve no relevnt fi nncil reltionships to disclose. Correspondence should be ddressed to: Frederic Picrd, MD, Deprtment of Orthopedics, Golden Jubilee Ntionl Hospitl, Agmemnon Street, Clydebnk, West Dunbrtonshire, G81 4DY, UK (frederic.picrd@gjnh.scot.nhs.uk). doi: / e855

2 Feture Article Totl knee rthroplsty (TKA) is considered successful opertion with beneficil outcomes for ptients with disbling rthritis of the knee. 1 Postopertive function nd stisfction re prtilly linked to postopertive rnge of movement (ROM). Fixed flexion contrcture is recognized compliction of TKA, which reduces ROM nd is source of morbidity for ptients. 2 Fixed flexion contrcture prevents the knee from chieving full extension. It is thought to be result of bnormlities in bony ntomy, s well s soft tissue contrcture nd tightness round the joint. 3 Fixed flexion contrcture cretes bnorml loding of the ffected knee joint. An incresed force cts on the posterior hlf of the tibil plteu, which is trnslted to the ptellofemorl joint. 3 This cuses qudriceps muscle ftigue, 4 nterior knee pin, ltered git mechnics, nd lower knee outcome scores nd ptient disstisfction with the rthroplsty. 2,4-7 With conservtive mngement, fixed flexion contrcture cn improve for up to 3 yers postopertively, but not ll resolve stisfctorily. 8 Revision surgery cn produce resonble improvement in ROM, but the risk of complictions with dditionl opertive procedures is high. 9 The best method of combting the problems creted by fixed flexion contrcture is primry prevention. In study of 5622 conventionl TKAs, Ritter et l 2 found the incidence of postopertive fixed flexion contrcture to be 3.6%. They identified sex, incresing ge, nd greter preopertive fixed flexion contrcture s risk fctors nd quntified the risk in ech cse. 2 They identified tht reduced body mss index (BMI) ws positively ssocited with incresed fixed flexion contrcture but doubted the vlidity of this finding becuse they reported tht their mesurements of the lrger legs of ptients with high BMIs my hve been inccurte. Theoreticlly, fixed flexion contrcture deformity cn be corrected during TKA by combintion of cutting more bone from the distl femur nd proximl tibi to increse the extension gp, soft tissue relese, nd precise component positioning. 10 Computer-nvigted surgery hs led to n improved bility to recrete neutrl coronl lignment of the lower limb, with comprison of conventionl techniques showing incresed ccurcy of femorl component positioning with nrrower rnge of results nd fewer outliers in computer-nvigted cohorts. 11,12 Computer nvigtion illustrtes the size of bone cuts, ids soft tissue blncing, 13 nd llows intropertive flexion nd extension to be ccurtely quntified. It my be expected tht use of computer nvigtion in TKA would reduce the incidence of postopertive fixed flexion contrcture. However, s fr s we re wre, no studies hve investigted whether computer nvigtion in TKA hs n effect on the incidence of postopertive fixed flexion contrcture. The primry im of this study ws to identify preopertive risk fctors for developing fixed flexion contrcture following TKA. The secondry im ws to quntify the effect of fixed flexion contrcture on outcomes t 2 yers. MATERIALS AND METHODS This work ws performed under the clinicl governnce procedures of our institution. All ptients in our institution who underwent TKAs between December 2003 nd Jnury 2007 nd hd ttended their 2-yer follow-up ppointment were identified using the hospitl s computerized dtbse (Excelicre; AsSys Technology Ltd, Pisley, United Kingdom). Cse notes nd Excelicre were routinely used to ccess dt recorded during dmission for opertion nd t 2-yer follow-up. Demogrphic dt collected included ge, BMI, sex, nd operted side. Preopertive dt collected were mximum ctive knee extension, mximum ctive knee flexion, nd Oxford Knee Score (scle from 12-60, with higher score indicting worse function). 14 Periopertive dt collected included preimplnt fixed flexion contrcture mesured with the ptient under nesthetic to the nerest 5 by the operting surgeon, type of implnt used s chosen by the surgeon bsed on preference (crucite retining or crucite scrificing/posterior stbilized), whether the opertion ws performed using computer nvigtion, nd whether the ptient ws referred for outptient physiotherpy fter hospitl dischrge. At 2-yer follow-up, ptient stisfction (s ssessed with 4-point Likert scle 15 : very stisfi ed, stisfi ed, unsure, nd disstisfi ed) nd mximum ctive knee flexion nd extension were recorded. Active knee joint ROM ws mesured by specilist rthroplsty prctitioners independent of this study. Mesurements were tken using plstic goniometers on the lterl spect of the leg with ptients in the supine position, using the verticl mid points of the thigh nd lower leg s reference points for the rms of the goniometer. Knees were grouped ccording to Ritter et l s 2 clssifiction of fixed flexion contrcture bsed on mesured ctive extension t 2-yer follow-up: 1. No fixed flexion contrcture: mximum extension ngles of 6 hyperextension to 5 flexion. 2. Intermedite fixed flexion contrcture: mximum extension ngles of 6 to 19 flexion. 3. Severe fixed flexion contrcture: mximum extension ngles of 20 flexion. These criteri were lso used to ctegorize the intropertive preimplnt flexion contrcture. Sttistics Dt were nlyzed using SPSS version 17.0 softwre (IBM 2010, Chicgo, Illinois) nd Excel 2003 (Microsoft, Redmond, Wshington). Groups were compred sttisticlly using Mnn-Whitney e856 ORTHOPEDICS ORTHOSuperSite.com

3 FLEXION CONTRACTURE FOLLOWING PRIMARY TKA GOUDIE ET AL Tble 1 Comprison of Ptient Demogrphics Between Groups Totl Cohort (N=811) No FFC Group (n=782) FFC Group (n=29) P Sex No. Women No. Men Side No. Left No. Right Age, y 69 [12] 69 [12] 72 [14].020 BMI 30.5 [7.1] 30.6 [7.0] 29.8 [8.4].968 Abbrevitions: BMI, body mss index; FFC, fi xed fl exion contrcture. Medin [interqurtile rnge] presented for continuous vribles. Tble 2 Comprison of Intropertive Dt Between Groups Totl Cohort (N=811) for continuous vribles nd chi-squred or Fisher s exct tests for ctegoricl vribles. Odds rtios were clculted where pproprite when sttisticlly significnt difference ws identified. Dt were incomplete for preopertive Oxford Knee Score, preopertive mximum flexion, preopertive extension, nd referrl to outptient physiotherpy. Therefore, only descriptive sttistics were clculted for these vribles. No. (%) No FFC Group (n=782) FFC Group (n=29) P Preimplnt FFC 219 (27) 206 (26) 13 (45).028 Nvigted 309 (38) 297 (38) 12 (41).711 Implnt type CR PS Abbrevitions: CR, crucite retining; FFC, fixed flexion contrcture; PS, posterior stbilized. Fisher s exct test. RESULTS The inclusion criteri were fulfilled by 815 primry TKAs. Four of these hd not hd ctive extension mesurements recorded t follow-up, so they were excluded. The study cohort ws 811 knees (806 ptients, 5 bilterl TKAs). The men time between opertion nd followup ws months (rnge, months). Twenty-nine knees (3.6%) hd n intermedite or severe fixed flexion contrcture (24 intermedite, 5 severe) mesured t 2-yer follow-up. Due to the smll numbers of severe fixed flexion contrcture, the cohort ws nlyzed s no fixed flexion contrcture nd fixed flexion contrcture where fixed flexion contrcture included both intermedite nd severe. Comprison of the demogrphics of the fixed flexion contrcture nd no fixed flexion contrcture group found tht sex nd ge differed significntly (Tble 1). Men were more likely to hve fixed flexion contrcture t 2 yers, with n odds rtio of 2.6, compred with women. Older ptients were more likely to hve fixed flexion contrcture. However, no significnt difference existed in the BMIs of the 2 groups (Tble 1). The intropertive dt were compred nd showed tht preimplnt fixed flexion contrcture nd implnt type were significntly different (Tble 2). Those with preimplnt fixed flexion contrcture were more likely to hve fixed flexion contrcture t 2 yers, with n odds rtio of 2.3. Proportionlly, more posteriorstbilized implnts were used in the fixed flexion contrcture group. No sttisticl differences existed in the proportion of nvigted surgeries in either group. The 2-yer follow-up outcomes for ech group were compred nd showed tht the Oxford Knee Score ws significntly higher nd mximum flexion nd stisfction were significntly lower in the fixed flexion contrcture group (Tble 3). The preopertive dt indicted tht Oxford scores nd mximum flexion were similr in the 2 groups nd tht mximum extension ws worse in the fixed flexion contrcture group. More ptients with fixed flexion contrcture t 2 yers hd been referred for outptient physiotherpy on dischrge (Tble 4). DISCUSSION The incidence of postopertive fixed flexion contrcture t 2 yers ws 3.6% in our series of 811 primry TKAs. These results re similr to those of Ritter et l, 2 who found the incidence of fixed flexion contrcture t 3 yers to be 3.6% in study of 5622 knees. It hs been shown tht continued improvement of fixed flexion contrcture cn be expected for up to 3 yers, so our figure my be slight overestimte. 3,8 This study ws retrospective review of dt collected s prt of routine clinicl prctice. Therefore, severl limittions e857

4 Feture Article Tble 3 Comprison of 2-yer Follow-up Dt Between Groups Totl Cohort (N 811) exist. Dt sets were not lwys complete. This ws prticulrly true for preopertive dt becuse severl ptients in our cohort hd been pressessed in other hospitls. It is not known whether ny trends exist in these missing dt. Also, it ws not possible to ssess ll risk fctors for developing fixed flexion contrcture. Theoreticlly, ptients with bilterl rthritis nd fixed flexion contrcture on the contrlterl side re more susceptible to developing fixed flexion contrcture in the operted knee s result of flexed knee stnce dictted by the nonoperted side. Effective postopertive physiotherpy cn help restore good ROM. 16 Pin or poor complince cn hmper this. These fctors crete sitution where fixed flexion contrcture cn rise regrdless of opertive technique. No FFC Group (n 782) FFC Group (n 29) P Oxford score 20 [11] 20 [11] 25 [15].003 Mximum flexion 100 [18] 100 [15] 90 [18].001 No. stisfied (%) 733 (90) 711 (91) 22 (76).036 b Abbrevition: FFC, fi xed fl exion contrcture. Medin [interqurtile rnge] presented for continuous vribles. b Fisher s exct test. Tble 4 Descriptive Sttistics for Vribles When Dt Collection Ws Incomplete Totl Cohort No FFC Group FFC Group No. 618/ /782 26/29 Preop Oxford score 43 [10] 43 [10] 44.5 [12] No. 549/ /782 17/29 Mx flexion, deg 100 [20] 100 [20] 100 [19] Mx extension, deg 5 [10] 5 [10] 10 [11] No. 744/ /782 29/29 OP physio (%) 336 (45) 318 (44) 18 (63) Abbrevitions: deg, degrees; FFC, fi xed fl exion contrcture; Mx, mximum; OP physio, outptient physicl therpy; Preop, preopertive. Medin [interqurtile rnge] presented for continuous vribles. In our cohort, we were not ble to collect complete dt sets for these vribles. Comprisons between subgroups must be interpreted with cre becuse ptients were not rndomized to different groups. For exmple, selection of the surgicl technique vried between surgeons with some tending to use nvigtion only in difficult cses while others used it for ll. The choice of implnt type lso vried between surgeons. It ws not possible to correct for these vribles between subgroups. Mle sex, incresing ge, nd the presence of preimplnt fixed flexion contrcture were identified s risk fctors for developing fixed flexion contrcture postopertively. This is in ccordnce with current literture. 2,8 This cohort showed men to be 2.6 times more likely thn women to develop postopertive fixed flexion contrcture 6 ; Ritter et l 2 found men to be 2.3 times more likely thn women to develop postopertive fixed flexion contrcture 10. Our series identified tht ptients with postopertive fixed flexion contrcture hd higher verge ge thn those without. Ritter et l 2 found tht more dvnced ge ws positively correlted with incidence of postopertive flexion contrcture 10. This cohort lso demonstrted tht ptients with preimplnt fixed flexion contrcture were 2.3 times more likely thn those without to develop postopertive fixed flexion contrcture 6. This is comprble to Ritter et l, 2 who found tht ptients with intermedite fixed flexion contrcture preopertively were t 2.9 times greter risk of developing postopertive fixed flexion contrcture 10. Lm et l 17 lso showed correltion with similr trend. Ritter et l 2 identified sttisticlly significnt 35% decrese in the chnce of postopertive flexion contrcture 10 for every 5-unit increse in BMI. They thought tht this correltion ws tenuous due to inccurcies encountered when using goniometers to mesure lrger legs. Our results support this explntion becuse we did not find ny significnt link between incresing BMI nd reduced risk of postopertive fixed flexion contrcture. A strength of our cohort ws its wide rnge of BMIs (rnge, kg/m 2 ) nd hving ll mesurements mde by experienced rthroplsty prctitioners, using stndrdized technique, working independently from the study. In the study by Ritter et l, 2 the surgeon mesured the extension ngle t follow-up ppointments. Despite the theoreticl dvntges, computer nvigtion did not significntly ffect the overll rte of fixed flexion contrcture. Incidence ws 3.9% in the computer-nvigted group nd 3.4% in the conventionl group. There were proportionlly more posterior-stbilized implnts in the fixed flexion contrcture group. However, this ws driven by sur- e858 ORTHOPEDICS ORTHOSuperSite.com

5 FLEXION CONTRACTURE FOLLOWING PRIMARY TKA GOUDIE ET AL geon choice nd my indicte tht knees tht re likely to develop fixed flexion contrcture hve other problems tht require the use of posterior-stbilized implnt rther thn ny direct reltionship between posterior-stbilized implnts nd fixed flexion contrcture. These results confirmed tht ptients with postopertive fixed flexion contrcture 6 following TKA hve poorer outcomes in terms of Oxford score, ROM, nd stisfction. This hs lso been shown by Ritter et l 2 nd highlights the importnce of ddressing this issue to minimize the number of ptients who suffer this compliction. The 2 gretest contributors to fixed flexion contrcture deformity from mechnicl point of view re bone deformity nd soft tissue tightness. Both of these fctors cn be ddressed during TKA nd stisfctory extension confirmed intropertively. Therefore, it would pper tht contributory fctors re involved tht re not esily identified intropertively. During intropertive exmintion of the knee, the pssive properties of skeletl muscle re the most redily pprecited nd re used to guide clinicl decisions. However, pssive tension is not good predictor of function. 18 The fixed flexion contrcture group of ptients lso hd reduced verge mximum ctive knee flexion t 2-yer follow-up, which my dd evidence to the hypothesis tht it is difficult to control some ptient-specific musculoskeletl properties t the time of surgery. This study found the incidence of fixed flexion contrcture following TKA to be 3.6%. Sex, incresing ge, nd the presence of preimplnt fixed flexion contrcture incresed the risk of hving fixed flexion contrcture t 2 yers postopertively. However, whether BMI ws high or low did not pper to be risk fctor. Our results dd weight to the findings of Ritter et l 2 nd indicte tht these figures cn be extrpolted to wide popultion. Further work on intr- nd periopertive musculoskeletl properties my shed some light on the residul number of fixed flexion contrctures fter TKA. REFERENCES 1. Victor J, Bellemns J. Physiologic kinemtics s concept for better flexion in TKA. Clin Orthop Relt Res. 2006; 452: Ritter MA, Lutgring JD, Dvis KE, Berend ME, Pierson JL, Meneghini RM. The role of flexion contrcture on outcomes in primry totl knee rthroplsty. J Arthroplsty. 2007; 22(8): McPherson EJ, Cushner FD, Schiff CF, Friedmn RJ. Nturl history of uncorrected flexion contrctures following totl knee rthroplsty. J Arthroplsty. 1994; 9(5): Tew M, Foster IW. Effect of knee replcement on flexion deformity. J Bone Joint Surg Br. 1987; 69(3): Mitsuysu H, Mtsud S, Miur H, Okzki K, Fukgw S, Iwmoto Y. Flexion contrcture persists if the contrcture is more thn 15 t 3 months fter totl knee rthroplsty [published online hed of print June 11, 2010]. J Arthroplsty. 2011; 26(4): Fehring TK, Odum SM. Surgicl tretment of flexion contrctures fter totl knee rthroplsty [published online hed of print July 27, 2007]. J Arthroplsty. 2007; 22(6 suppl 2): Perry J, Antonelli D, Ford W. Anlysis of knee joint forces during flexed knee stnce. J Bone Joint Surg Am. 1975; 57(7): Aderinto J, Brenkel IJ, Chn P. Nturl history of fixed flexion deformity following totl knee replcement: prospective five-yer study. J Bone Joint Surg Br. 2005; 87(7): Hrtmn CW, Ting NT, Moric M, Berger RA, Rosenberg AG, Dell Vlle CJ. Revision totl knee rthroplsty for stiffness. J Arthroplsty. 2010; 25(6 suppl): Mson J, Fehring TK, Estok R, Bnel D, Fhrbch K. Met-nlysis of lignment outcomes in computer-ssisted totl knee rthroplsty surgery. J Arthroplsty. 2007; 22(8): Kim SJ, McDonld M, Hernndez J, Wixson RL. Computer ssisted nvigtion in totl knee rthroplsty: improved coronl lignment. J Arthroplsty. 2005; 20(suppl 3): Bäthis H, Perlick L, Tingrt M, Lüring C, Zurkowski D, Grifk J. Alignment in totl knee rthroplsty: A comprison of computer-ssisted surgery with the conventionl technique. J Bone Joint Surg Br. 2004; 86(5): Picrd F, Dekin AH, Clrke JV, Dillon JM, Kinninmonth AW. A quntittive method of effective soft tissue mngement for vrus knees in totl knee replcement surgery using nvigtionl techniques. Proc Inst Mech Eng H. 2007; 221: Dwson J, Fitzptrick R, Murry D, Crr A. Questionnire on the perceptions of ptients bout totl knee replcement. J Bone Joint Surg Br. 1998; 80(1): Likert R. A Technique for the Mesurement of Attitudes. Archives of Psychology, No. 140 [doctorl disserttion]. New York, NY: Columbi University; 1932: Lenssen AF, De Bie RA. Role of physiotherpy in peri-opertive mngement in totl knee nd hip surgery. Injury. 2006; (suppl 5):S41-S Lm LO, Swift S, Shkespere D. Fixed flexion deformity nd flexion fter knee rthroplsty. Wht hppens in the first 12 months fter surgery nd cn poor outcome be predicted? Knee. 2003; 10(2): Leibger RL. Form nd Function of skeletl muscle. 223 In: Einhorn TA, O Keefe RJ, Buckwlter JA, eds. Orthopedic Bsic Science Foundtions of Clinicl Prctice. 3rd ed. Rosemont, IL: AAOS; 2007: e859