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Predictive risk factors for stif knees in total knee arthroplasty


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Predictive risk factors for stif knees in total knee arthroplasty

  1. 1. The Journal of Arthroplasty Vol. 21 No. 1 2006 Predictive Risk Factors for Stiff Knees in Total Knee Arthroplasty Rajiv Gandhi, MD,* Justin de Beer, MD, FRCSC,*y James Leone, MD, FRCSC,* Danielle Petruccelli, MLIS,y Mitchell Winemaker, MD, FRCSC,*y and Anthony Adili, MD, PEng, FRCSC*z Abstract: Retrospective review of 1216 primary total knee arthroplasties (TKAs) to evaluate incidence and predictors of arthrofibrosis, defined as flexion less than 908 1 year post-TKA. Incidence of stiffness post-TKA was 3.7% (45/1216). A matched case-control study was then conducted to identify predictive factors for this outcome. Preoperative flexion and intraoperative flexion were predictive of ultimate postoperative flexion ( P = .001 and P = .039, respectively). There was no correlation between postoperative stiffness and specific medical comorbidities, including diabetes. Preoperative and postoperative relative decreased patellar height and stiffness postoperative were significantly correlated ( P = .001). Although stiffness post-TKA is multifactorial, careful attention to surgical exposure, restoring gap kinematics, minimizing surgical trauma to the patellar ligament/extensor mechanism, appropriate implant selection, and physiotherapy combined with a well-motivated patient may all serve to reduce the incidence of stiffness post-TKA. Key words: total knee arthroplasty, stiffness, arthrofibrosis, outcome, range of movement. n 2006 Elsevier Inc. All rights reserved.The goal of total knee arthroplasty (TKA) is to true incidence is difficult to discern from theprovide a stable painless knee with adequate range literature because of the lack of a uniform defini-of motion for activities of daily living. Studies have tion for stiffness.shown that 838 of flexion is required for stair As documented in the literature, stiffness afterclimbing, 938 for rising from a seated position, and TKA can be attributed to poor preoperative and1068 for shoelace tying [1]. The incidence of intraoperative range of motion [2-5], intraoperativearthrofibrosis after TKA is generally low, but its technical problems [4,6,7], obesity [8], preoperative varus/valgus alignment [9], and poor patient reha- bilitation after surgery [6,7,10]. Most often, how- ever, no cause can be identified [5,6,10]. Others From the *Faculty of Health Sciences, McMaster University, have suggested that having diabetes may predisposeHamilton, Ontario, Canada; yHamilton Health Sciences Henderson a patient to arthrofibrosis [11]; however, this is notHospital, Hamilton, Ontario, Canada, and z St. Joseph’s HealthcareHamilton, Hamilton, Ontario, Canada. well defined in the literature. Submitted November 23, 2004; accepted June 9, 2005. A retrospective review of 1216 primary TKAs No benefits on funds were received in support of the study. performed at a high-volume tertiary care orthope- Reprint requests: Danielle Petruccelli, MLIS, HamiltonArthroplasty Group, Hamilton Health Sciences Henderson dic center between 1998 and 2002 was conductedHospital, 711 Concession St., Hamilton, Ontario, Canada to identify the incidence of and predictive factorsL8V 1C3. associated with knee flexion less than 908 at 1 year n 2006 Elsevier Inc. All rights reserved 0883-5403/06/1906-0004$30.00/0 after TKA. The average progression of knee flexion doi:10.1016/j.arth.2005.06.004 within the first year after TKA was also evaluated to 46
  2. 2. Predictive Risk Factors for Stiff TKA ! Gandhi et al 47 Table 1. Baseline Characteristics All surgeries used a standard midline incision with medial parapatellar arthrotomy for exposure SG (SD) CG (SD) (n = 45) (n = 45) P of the knee. All posterior osteophytes were re- moved and soft tissue release was performed asAge 67.7 (8.8) 67 (9.6) .667 necessary to balance the knee. All TKA compo-Sex (M:F) 12:33 12:33 – nents were cemented.BMI 35 (8.5) 33.1 (6.2) .271ASA rating Patient medical records, operative notes, and ASA 1 1/45 1/45 – radiographs were reviewed. Potential predefined ASA 2 34/45 34/45 – predictive factors of stiffness included preoperative ASA 3 10/45 10/45 –Preoperative medical comorbidities, surgical skin-to-skin time, alignment estimated blood loss, intraoperative and postopera- Varus:valgus 35:10 31:14 .340 Mean varus 9.6 (7.4) 9.21 (6) .796 tive complications, and revision rate. Functional Mean valgus 6.7 (2.9) 8.9 (4.2) .169 assessment, completed by a physiotherapy assistant,Preoperative flexion 90 (21.4) 102.4 (16.6) .005 included range of motion and Knee Society ScorePreoperative KSS 30.8 (15.4) 36.2 (13.6) .112 (KSS) preoperatively and at 6 weeks, 6 months, andPreoperative 41.2 (5.4) 41.8 (7.9) .702 Oxford Score 1 year postoperatively [13]. The clinical KSS scoringPreoperative 1.09 (0.12) 1.16 (0.14) .025 component assesses pain, range of motion, and patellar height stability. Patients were also asked to complete thePreoperative 6.7 (2.7) 6.1 (2.1) .159 tibial slope Oxford Knee functional score at like intervals [14]. Radiographic analysis included tibiofemoral align- Bold denotes statistically significant. BMI indicates body ment measured from long-leg standing radiographs,mass index. tibial slope, and the Insall-Salvati (IS) ratio for patellar height [15]. The IS method has a normal ratio of 0.8 to 1.2 with patella infra defined as aprovide some guidelines with respect to possible patella height ratio less than 0.8 and patella altaclosed/open manipulation for the treatment of defined as a patella height ratio greater than 1.2.early postoperative arthrofibrosis. The ratio is defined as the length of the patella ligament divided by the longest coronal length of the patella [15]. Materials and Methods To determine statistical significance between the two groups, paired t tests were conducted on all A retrospective review of 1216 primary TKAs continuous variables. The v 2 or Fisher exact test,performed for a diagnosis of osteoarthritis at a single where appropriate, was conducted on all categori-tertiary care orthopedic center among 5 surgeons cal variables. Multiple linear regression analysisfrom September 1998 to May 2002 identified 45 was also conducted to identify factors predictive ofTKAs with a 1-year postoperative flexion range of stiff TKA. P b .05 was considered statisticallyless than 908. We identified these patients through significant. All statistical analyses were performedour prospective arthroplasty database that records using SPSS version 10.information on all patients who undergo total jointarthroplasty at our hospital. These 45 stiff TKAswere matched to 45 TKAs with greater than 908 Resultsflexion at 1 year postoperative. Cases and controlswere matched one-to-one for age, sex, body mass The incidence of stiffness post-TKA was 3.7% (45/index, American Society of Anesthesiologists (ASA) 1216). The stiff TKA cohort comprised 12 (26.7%)rating [12] (as a means of classifying patients males and 33 (73.3%) females. One (2.2%) of 45according to the extent of their systemic disease), patients was rated as ASA 1, 34 (75.6%) were ratedsurgeon, implant type, and fixation. Cases and as ASA 2, and 10 (22.2%) as ASA 3 (Table 1).controls were then assessed within a nested case- Thirty-seven (82.2%) of 45 knees in the stiff TKAcontrol study to determine predictive factors of stiff group (SG) were implanted with a posterior stabi-TKA. Flexion of 908 was chosen as our definition of lized total knee and 8 (17.8%) with a cruciate-stiffness because this would provide adequate retaining total knee. All implants were cemented.motion for patients to perform activities of daily Three (6.7%) of 45 knees had previously undergoneliving, including stair climbing and rising from a high tibial osteotomy.seated position. All patients in both groups had a Two (4.4%) of 45 cases in the stiff TKA cohortpreoperative diagnosis of osteoarthritis. were receiving associated worker’s compensation
  3. 3. 48 The Journal of Arthroplasty Vol. 21 No. 1 January 2006 Table 2. Preoperative Medical Comorbidities Preoperative patellar height was significantly different between the two groups with an IS ratio SG (SD) (n = 45) CG (SD) (n = 45) P of 1.09 (F0.12) in the SG vs 1.16 (F0.14) in theAnemia 6.7 4.4 .5 CG. ( P = .025). Postoperative patellar height wasAngina 15.6 8.9 .334 also significantly different between the two groupsDiabetes 17.8 6.7 .108 with an IS ratio of 1.02 (F0.39) in the SG com-Heart Disease 26.7 6.7 .011Hypertension 51.1 53.3 .833 pared with 1.27 (F0.26) in the CG ( P = .001).Stroke 6.7 6.7 – Although there was a significant change in IS ratioPrevious MI 11.1 0 .056 in the CG from 1.16 preoperative to 1.27 postop-Nil 28.9 31.1 .818 erative ( P = .006), there was no significant change Values are expressed as percentage. Bold denotes statistically in IS ratio preoperative and postoperative in thesignificant. MI indicates myocardial infarction. SG ( P = .45). The number of patients with patella infra (IS b0.8) significantly increased postoperative in the SG from 0 of 45 patients preoperative vsbenefits as compared with 1 (2.2%) of 45 cases in 18 of 45 patients postoperative ( P b .0001). Therethe control group (CG) ( P = .5). was no significant difference in the number of The observed incidence of significant preopera- patients with patella infra (IS b0.8) preoperativetive comorbid factors, including anemia, diabetes, and postoperative in the CG (1/45 patientsangina, heart disease, previous myocardial infarc- preoperative vs 1/45 patients postoperative; P N .05).tion, hypertension, and stroke, among the two There was no difference between the two groupscohorts is outlined in Table 2. Of the SG, with regard to preoperative tibiofemoral alignment14 (31.1%) of 45 patients presented with only (Table 1) or mean postoperative valgus alignment1 comorbidity, whereas 7 (15.6%) presented with (4.88 [F2.5] for the SG and 4.68 [F3.2] for the CG;2 comorbidities and 11 (24.4%) with 3 or more P = .631). Both groups had a significant differencecomorbidities. Comparatively, 24 (53.3%) of in preoperative and postoperative tibial slope45 patients within the CG presented with 1 comor- (SG: 6.7 [F2.7] preoperative vs 2.5 [F2.4] postop-bidity ( P = .033), 5 (11.1%) with 2 comorbidities erative, P b .0001; CG: 6.1 [F2.1] preoperative vs( P = .535), and 2 (4.4%) with 3 or more comorbid- 2.0 [F2.6] postoperative, P b .0001). However,ities ( P = .007). Thirteen (28.9%) of 45 patients in there was no statistically significant difference inthe SG did not present with a preoperative comor- postoperative tibial slope between the SG andbidity as compared with 14 (31.1%) of 45 in the CG CG ( P = .390).( P = .818). There was no statistically significant difference in Mean intraoperative flexion at time of wound mean KSS preoperatively (Table 1) or at 6 weeksclosure was 108.68 (F23.7) for the SG, comparedwith a mean flexion of 120.48 (F7.9) for the CG( P = .039). Mean skin-to-skin operative time was Table 3. Clinical Outcomes81.4 minutes (F22.6) for the SG and 78.6 minutes SG (SD) CG (SD)(F18.5) for the CG ( P = .611). (n = 45) (n = 45) P There were intraoperative complications associ-ated with 3 (6.7%) of 45 knees in the SG and Flexion1 (2.2%) of 45 knees in the CG ( P = .616). Intraoperative 108.6 (23.7) 120.4 (7.9) .039 at closureIntraoperative complications in the SG included 6-wk 79.4 (16.9) 101.1 (10) b.00013 partial patellar tendon avulsions repaired with 6-mo 87.5 (12.9) 110.1 (10.3) b.0001corkscrew suture anchors. Given that the SG had 1-y 80.2 (13.4) 111 (7.5) b.0001 KSSpoor preoperative range of flexion, intraoperative 6-wk 69.2 (17.8) 77.8 (17.4) .106exposure was in general more difficult to achieve, 6-mo 77.1 (14.4) 86.7 (16.1) .05thus explaining the increased incidence of patellar 1-y 75.7 (16.6) 85 (15.9) .014 Oxford Kneetendon avulsion. The intraoperative complication in Scorethe CG was a proximal tibia fracture repaired with 6-wk 36.5 (6.9) 31.8 (8.6) .0402 screws. All complications resolved uneventfully. 6-mo 30.3 (9.2) 28.1 (10.2) .331 1-y 29.2 (9.8) 27.9 (9.7) .519 Mean knee flexion at all intervals observed, Postoperative 1.02 (0.39) 1.27 (0.26) .001including preoperative (Table 1), intraoperative at patellar heighttime of wound closure, 6 weeks, 6 months, and Postoperative 2.5 (2.4) 2.0 (2.6) .390 tibial slope1 year, was significantly different between the twogroups (Table 3). Bold denotes statistically significant.
  4. 4. Predictive Risk Factors for Stiff TKA ! Gandhi et al 49and 6 months postoperatively. However, 1-year flexion less than 758. Previous authors havepostoperative KSS was significantly different be- reported incidence of stiff and painful knee as hightween the SG with a mean score of 75.7 (F16.6) as 8% to 12% [11]. We found an incidence of 3.7%and the CG with a mean score of 85 (F15.9) at 1 year where stiffness was defined as flexion less( P = .014) (Table 3). than 908. The decreased incidence of stiffness may Mean Oxford Score was significantly different be- be due to improved prosthetic design, improvedtween the SG and CG at 6 weeks postoperative (36.5 instrumentation allowing more reproducible align-[6.9] and 31.8 [8.6], respectively; P = .040) (Table 3). ment, improved understanding of soft tissue and Two (2.2%) of 45 patients in the SG experienced gap balancing, and a greater variety of implant sizesearly postoperative complications, including to best match the patient’s native anatomy.1 patient who had a bleed into the operative leg There was a trend signifying an increase inat 10 days postoperatively and 1 patient who technical difficulty in the SG in our study. Mostdeveloped a surgical wound infection. Similarly, significantly, we observed several patellar ligament2 (2.2%) of 45 patients in the CG had postoper- avulsions and an increased operative time in theative complications including 1 patient who de- SG. Furthermore, we found that the SG had aveloped an Escherichia coli infection in both the significantly decreased flexion range of movementblood and urine 3 weeks postoperatively, but (ROM) against gravity at the end of the operativewithout involvement of the knee arthroplasty. procedure compared with the CG. This may be aAn additional patient had a wound infection reflection of a preoperatively contracted extensor8 months postoperatively after a blow to the knee mechanism or difficulty in achieving proper gapwith deep infection secondary to posttraumatic kinematics in this subgroup of patients.hemarthrosis ultimately requiring removal of the Many previous authors have looked at identify-TKA components with subsequent TKA revision at ing predictive factors for arthrofibrosis after TKA.11 months postoperatively. All remaining compli- Ritter et al [4] identified preoperative flexion ascations resolved uneventfully. the principal predictive factor of postoperative Three (6.7%) of 45 TKAs in the SG required ROM. This finding has also been confirmed byrevision, including 1 TKA revision for stiffness numerous other authors [2,3,5]. The more limited23 months postoperatively and 2 TKAs for aseptic the preoperative ROM, the greater the likelihoodfailure at 22 and 29 months post–primary TKA. that the associated stiffness of the extensor mech-Likewise, there were 3 (6.7%) reoperations in anism may contribute to limited flexion afterthe CG including 2 TKA revisions for aseptic surgery. Further studies have also identified intra-failure at 9 and 25 months, respectively, and 1 for operative ROM [19], preoperative varus/valgusinfection at 9 months post–primary TKA as tibiofemoral angle [9], preoperative diagnosisindicated previously. [20], body weight [8], surgical closure [21], and Multiple linear regression analysis revealed that type of implant [22] as predictive factors for a stiffpreoperative flexion and flexion at time of surgical TKA. We found that preoperative, intraoperative,closure and 6 weeks and 6 months postoperatively 6-week, and 6-month flexions are all predictive ofwere predictive of stiff TKA at 1 year. Likewise, a stiff knee at 1 year postoperatively.patellar height as determined at 1 year by the IS The issue of patella infra limiting flexion in TKAratio was also predictive of a stiff TKA ( P = .001). has been well established particularly with TKA after closing wedge high tibial osteotomy [23]. The patella can be relatively low lying secondary to Discussion joint line elevation or from scarring and subsequent shortening of the infrapatellar tendon [24]. Figgie Knee flexion after TKA correlates closely with et al [7] found that joint line elevation greater thanpatient satisfaction and function [16]. The inci- 10 mm in a posterior stabilized knee limits flexion,dence of stiffness after TKA varies based on the whereas Shoji et al [8] showed the same result withdefinitions used. Scranton [17] defined stiffness as 16 mm of joint line elevation. Schurman et al [25],flexion less than 858; Christensen et al [6] defined it however, looked at the distance from the patella toas an arc of motion less than 708; and Nicholls and the joint line and found no correlation betweenDorr [18] defined it as flexion contracture greater this value and the flexion outcome at 1 year. Ourthan 208 or a total range of motion less than 458. study found a significantly lower patellar heightKim et al [10] reported an incidence of 1.3% at a between the SG and CG preoperatively and post-mean follow-up of 32 months where stiffness was operatively. Furthermore, the SG experienced adefined as flexion contracture less than 158 and/or significant decrease in the IS ratio postoperatively,
  5. 5. 50 The Journal of Arthroplasty Vol. 21 No. 1 January 2006whereas the CG displayed an increase in the IS flexion over the next 6 months. Based on theseratio postoperatively. There was a significantly findings, patients with preoperative stiffness need togreater number of patients with true patellar infra be counseled that postoperative range of motion(IS b0.8) in the SG compared to the CG postoper- may not significantly improve post-TKA. Further-atively (18/45 in the SG vs 1/45 in the CG). We feel more, range of motion at 6 months post-TKA maythat the increased difficulty in exposure associated represent the maximum flexion arc one can expectwith a stiff knee may require a more aggressive despite further nonoperative measures.resection of the fat pad and greater traction on the The options for management of the stiff total kneealready relative short patellar tendon resulting in include aggressive physiotherapy, closed manipula-the potential for increased scarring and shortening tion F arthroscopic lysis of adhesions, posteriorof the patellar tendon postoperatively. Conse- cruciate ligament recession or resection, openquently, scarring of the infrapatellar tendon from debridement, or revision surgery [5,6,10,11]. Thereaggressive resection of the fat pad or elevation of is no consensus in the literature as to the optimalthe joint line may contribute to stiffness post-TKA. timing for closed manipulation of a stiff total knee.These findings suggest that the SG developed Brassard and Scuderi [30] recommended manipu-scarring and/or true shortening of the patellar lation if ROM is less than 758 by 6 to 12 weeks andtendon when compared with the CG. Moreover, Scranton [17] recommended manipulation if flex-relative patella infra preoperatively was also found ion is less than 908 at 6 weeks, whereas Fox and Possto correlate with poor postoperative range of [31] recommended manipulation by 2 weeks ifmotion and stiffness at 1 year. Although an IS ratio ROM is less than 908. Given our findings that stiffof 1.02 in the SG postoperative does not represent TKA patients experience improvement in theirpatellar baja by the IS definition, one must keep in average ROM at 6 weeks with a plateau in kneemind that the normal values after TKA have not flexion reached at 6 months postoperatively, webeen established. As such, we concluded that the suggest that closed manipulation be considered forrelative patellar height difference between the two those patients with flexion less than 808 beforegroups was still an important finding. 10 weeks, as there is no advantage to the patient in Diabetes mellitus has been suggested as a risk delaying this intervention further. The patient withfactor for arthrofibrosis after TKA [11]. Others have less than 908 flexion at 6 months will not benefitshown increased rates of infections, both superficial from observation alone, but rather warrants consid-and deep, as well as higher revision rates in those eration for surgical intervention. Babis et al [5]with diabetes [26-28]. Our study did not identify reviewed the Mayo Clinic experience with arthrol-any medical comorbidities to be associated with ysis of adhesions and tibial liner exchange to alimited flexion at 1 year, including diabetes. thinner polyethelene and found no benefit to thisHowever, it was noted that the SG had a signifi- intervention and do not recommend its use for thecantly higher number of preoperative comorbidities management of a stiff total knee. Christensen et alper patient as compared with the CG. This may [6] reported excellent results after full revision ofsuggest some form of intrinsic systemic predisposi- stiff TKAs having less than 708 arc of motion at antion to scar tissue formation. Further analysis average of 37 months of follow-up.revealed that this difference was largely attribut- The stiff TKA represents a particularly difficultable to preexisting cardiac disease. This, in our challenge to the arthroplasty surgeon. Maximizingopinion, more strongly suggests severe preopera- patient knee ROM preoperatively with physiother-tive deconditioning, which may in turn compro- apy would be well served based upon our findingsmise the physical ability of the patient to fully and those of other investigators [2-5,19]. However,participate in the routine postoperative rehabilita- this recommendation should be individualized astion protocol, thus negatively impacting ultimate some patients may find that aggressive preoperativerange of motion achieved. physiotherapy may exacerbate their overall level of Many authors have previously described maxi- symptoms. Furthermore, patients with preoperativemal flexion being obtained at 1 year [3,29], whereas comorbidities that may affect their ability to partic-Ritter et al [4] showed that there was only a 2.88 ipate fully in a postoperative rehabilitation programincrease in flexion in their patients from the may benefit from preoperative counseling and an6-month mark to 3 years. From our study, we appropriately modified rehabilitation program.found that ROM continued to improve in all However, further study is required to fully addresspatients until the 6-month follow-up visit, after this issue. More specifically, patients with preoper-which time, the SG lost an average of 7.38 of flexion, ative relative patella infra are at an increased risk ofwhereas the CG gained an average of only 0.98 of developing stiffness by 1 year postoperatively.
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