Cruciate-Retaining Total Knee Arthroplasty in Patients with at Least Fifteen Degrees of Coronal Plane Deformity

The Journal of Arthroplasty Vol. 23 No. 3 2008

Cruciate-Retaining Total Knee Arthroplasty in Patients with at Least Fifteen Degrees of Coronal Plane Deformity Paul Kubiak, MD, Michael J. Archibeck, MD, and Richard E. White Jr., MD

Abstract: There has been debate regarding the superiority of posterior stabilized (PS) or cruciate-retaining knee designs in total knee arthroplasty (TKA). The proponents of PS TKA argue that a relative contraindication to the use of cruciateretaining total knee arthroplasty is that of significant coronal plane deformity. The purpose of this study is to compare our minimum 10-year results of posterior cruciate ligament–retaining TKAs in patients with preoperative coronal plane deformity of at least 158 (z108 of varus or z208 of valgus) to historical results of PS TKA designs in similar patients. We found, at a minimum 10-year follow-up, very good results with a 93% (95% confidence interval, 87%-98%) revision-free survivorship at 10 years and no revisions for instability or loosening. Key words: primary knee arthroplasty, deformity, cruciate-retaining. n 2008 Elsevier Inc. All rights reserved.

TKAs in patients with a preoperative coronal plane deformity of at least 158 (z108 of varus or z208 of valgus) is equivalent to historical results of PCL substituting TKAs in patients with large preoperative coronal plane deformities.

There has been significant debate as to the superiority of posterior stabilized or cruciate-retaining knee designs in total knee arthroplasty (TKA). The proponents of posterior stabilized TKA argue that a relative contraindication to the use of posterior cruciate ligament (PCL)–retaining total knee arthroplasty is that of significant coronal plane deformity [1-3]. They argue that retaining the PCL in such cases can make soft tissue balancing more difficult, and the PCL may contribute to the deformity. The senior author performed cruciateretaining TKAs nearly exclusively throughout his career. The hypothesis of this study is that the minimum 10-year results of these PCL-retaining

Materials and Methods From 1985 through 1995, the senior author (R.E.W.) performed a total of 751 TKAs in 523 patients. A posterior cruciate-retaining design was used in all of these patients. A review of the senior surgeon’s database was performed to locate all patients with a preoperative coronal plane deformity of at least 158 on preoperative, weight-bearing anteroposterior radiographs (at least 108 of anatomic varus or at least 208 of anatomic valgus). All measurements were made using a long graduated goniometer on standard short (14  17 in) weightbearing radiographs and were reviewed by an unbiased observer. Inclusion in the review was based solely on the level of deformity on AP standing preoperative radiographs with no specific

From the New Mexico Center for Joint Replacement Surgery, Albuquerque, New Mexico. Submitted June 28, 2006; accepted January 3, 2007. No benefits or funds were received in support of the study. Reprint requests: Paul Kubiak, MD. New Mexico Center for Joint Replacement Surgery, 201 Cedar, SE, Suite 6600, Albuquerque, New Mexico 87106. n 2008 Elsevier Inc. All rights reserved. 0883-5403/08/2303-0007$34.00/0 doi:10.1016/j.arth.2007.01.004

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exclusion criteria based on etiology of disease or medical comorbidities. Components used included both cemented and uncemented designs. The decision of which component type to use was determined by the senior surgeon and was based on patient age and bone quality. Cemented components were precoated components with 4 tibial fixation pegs. Cementless designs included a titanium fiber metal ingrowth surface with supplemental tibial screw fixation. The surgical technique included the use of the mid vastus approach [4] using a measured resection technique. The same surgical technique was performed by the senior surgeon throughout the study period without substantial changes. The distal femoral resection angle was made based on preoperative templating as the difference between the anatomic and mechanical axis as measured on long AP radiographs of the entire extremity. Femoral rotation was parallel to the posterior condylar axis. The femoral instrumentation system was an anterior referencing guide. The tibial cut was made using an extramedullary guide with preservation of the PCL. When necessary, PCL recession to allow for proper soft tissue balancing was typically performed as a graduated release of any tight bands of the PCL in flexion off the femoral insertion. A more constrained polyethylene was used in all cases of a recessed or sacrificed PCL. Once the cuts were made and the trials were placed, soft tissue releases were performed to obtain, as best possible, rectangular flexion and extension spaces. Soft tissue releases were decided upon by the senior surgeon and were determined intraoperatively and recorded into the surgical database. Clinical evaluation, pre- and postoperatively, included physical examination and completion of a Knee Society Score evaluation form. Examinations were performed at 6 weeks, 6 months, and 1, 3, 5, 8, 10, 12, and 15 years postoperatively. Manual examination was used to assess knee stability to valgus and varus stresses as well as to anteroposterior translation at 908 of flexion. All clinical examinations were performed by the senior surgeon. Radiographs were reviewed by an unbiased observer not involved in patient’s care. Weight-bearing anteroposterior, non–weightbearing lateral, and Merchant patella radiographs of the operative knees were taken at all follow-up visits. Radiographs were reviewed for alignment of the implants as well as for evidence of polyethylene wear, osteolysis, or radiolucencies. Radiographic zones developed for this pegged design were used for reporting [5].

Implant survival and data regarding complications were reviewed in the database for all subjects. Survival estimates were generated by the KaplanMeier method using the LIFETEST procedure in SAS statistical software (SAS for the Windows XP platform on the personal computer, version 8.02, SAS Inc, Cary, NC). Plots of survival curves were generated using the SAS GPLOT procedure. Kaplan-Meier estimates of implant survival are nonparametric, and no additional statistical tests were performed. However, a lack of statistical difference in implant survival may be inferred (with a common 5% error rate) when 95% confidence intervals (CIs) for survival estimates overlap.

Results Review of the data for the 751 cruciate-retaining TKAs showed that of these knees, 111 in 93 patients had a preoperative coronal plane deformity of at least 158. Eighty knees had a preoperative varus deformity (mean, 12.68; range, 10-21). Thirty-one knees had a preoperative valgus deformity (mean, 23.28; range, 20-32). Flexion contractures were present in both groups with the range of preoperative passive extension in the varus group from 08 to 158 (mean, 1.10) and in the valgus group from 08 to 108 (mean, 0.64). There were 39 men and 54 women. The mean age at the time of surgery was 71 years (range, 36-89 years). Sixteen patients underwent bilateral procedures, all performed simultaneously. The diagnosis of these patients included primary osteoarthritis (101), rheumatoid arthritis (8), and posttraumatic arthritis (2). Of the 93 patients, 35 patients (40 knees) died before 10-year follow-up, and 6 patients (7 knees) were lost to follow-up, leaving 64 knees in 52 patients with minimum 10-year clinical followup. The mean follow-up for these 64 knees was 12 years (range, 10-17 years). Of these 64 knees, 47 had complete radiographic follow-up. The PCL-retaining prosthesis used in these 93 patients included 14 Miller-Galante I, 82 MillerGalante II, and 15 NexGen designs (Zimmer, Warsaw, Ind). Fixation methods included 51 cemented knees (all 3 components), 42 cementless knees (20 with cementless patellae and 22 with cemented patella), and 18 hybrid knees (cemented tibia and patellae). All patellae were resurfaced. The polyethylene inserts included 50 flat unconstrained and 61 anteroposterior lipped. Posterior cruciate ligament recession to allow for proper soft tissue balancing was deemed necessary in 42 knees (33 with preoperative varus, 9 with

368 The Journal of Arthroplasty Vol. 23 No. 3 April 2008 preoperative valgus). There were 3 cases of an babsentQ PCL, 2 cases of an binadequateQ PCL, and 7 cases in which the PCL was bsacrificedQ as noted in the operative reports. A more constrained polyethylene (anteroposterior lipped or anterior constrained polyethylene bearings; Zimmer) was used in all cases of a recessed, sacrificed, or incompetent PCL. For varus knees, there was a titrated release of the superficial medial collateral ligament in 17 cases. For valgus knees, this included a release of the iliotibial band (6 cases), lateral collateral ligament release (7 cases), and 1 medial collateral release. Lateral retinacular release was performed for any patellar tilt with trialing (positive dno thumb testT). This was deemed necessary in 19 of the valgus knees and 34 of the varus knees. For the entire group of 111 TKAs, there were no intraoperative complications. Postoperative complications included 4 cases of documented deep venous thrombosis, 2 cases of significant ileus, 2 late periprosthetic femoral fractures (treated nonsurgically), 3 infections, and 1 patella dislocation. In the 64 knees in 52 patients with a minimum 10-year clinical follow-up, the Knee Society Score improved from a mean of 35.48 (range, 12-65) preoperatively to a mean of 92.20 (range, 67-100) at latest follow-up. The mean preoperative range of motion was from 38 (range, 0-15) of flexion contracture to 1008 (range, 70-120) of flexion. At most recent follow-up, this improved to a mean 18 (range, 0-5) of flexion contracture to 1198 (range 908-1308) of flexion. No knee had greater than 3 mm of posterior translation as measured manually at 908 of flexion at most recent follow-up. No knee had greater than 5 mm of medial laxity to valgus manual stress or greater than 4 mm of lateral laxity to varus manual stress at final follow-up. Of the 64 knees with at least 10 years of clinical follow-up, there were 3 revisions and no additional reoperations. One was a polyethylene exchange at 7 years postoperatively for excess polywear and tibial osteolysis. The patient’s preoperative knee alignment was 138 of varus, and the original prosthesis (which was retained at revision) was a fully cementless construct with a flat polyethylene insert. The second revision was an all component revision for tibial osteolysis, asymmetric polyethylene wear, and fracture of the patella implant at 6 years post index procedure in a patient who had a preoperative alignment of 288 of valgus. The final revision in this group was performed for infection. There were no revisions for tibiofemoral instability or aseptic loosening. There were no revisions for clinically identified late PCL insufficiency.

In the group of patients that died or were lost before the 10-year follow-up, we know of 2 revisions for infection (both resected) and 1 isolated patellar revision for patellar dislocation. These were included in the survivorship calculations. Using any revision as the end point for the entire group of 111 knees in 93 patients, the 10-year survivorship was 93% (95% CI, 87%-98%). Survivorship with aseptic loosening of any component as the end point was 100%. For the subgroup of 42 knees with equal to or greater than 108 of varus preoperatively, the knee scores improved from a mean of 39 (range, 22-65) to a mean of 95 (range, 88-100) at the most recent follow-up. No knee was found to have anteroposterior translation at 908 of flexion greater than 3 mm. Ten-year survivorship for the group with a preoperative varus deformity, using any revision as the end point, was 91.7% (95% CI, 85%-99%). For the subgroup of 44 knees with equal to or greater than 208 of valgus preoperatively, the knee scores improved from a mean of 28 (range, 12-47) to a mean of 92 (range, 67-100) at the most recent follow-up visit. No knee was found to have anteroposterior translation at 908 of flexion greater than 3 mm. Ten-year survivorship for the group with a preoperative valgus deformity using any revision as the end point was 96.2% (95% CI, 89%-100%). Of the 64 knees with at least 10-year clinical follow-up, 44 had complete radiographic follow-up as well. There were 6 cases of tibial osteolysis, all noted in patients with cementless tibial components. One of these cases underwent revision as noted above. The location of these areas of osteolysis (based on the Knee Society radiographic evaluation system [6]) included one 2-mm lesion in zone 1, one 2-mm and one 5-mm lesion in zone 3, one 5-mm lesion in zone 4, and one 5-mm lesion in zone 5. There were also 6 cases of tibial radiolucencies noted, again all occurring in patients with cementless tibial prostheses. One of these patients had a revision for infection, and all these patients had the radiolucencies about the posteromedial or posterolateral screws through the tibial base plate. There were 4 cases of patellar radiolucencies all in cementless patella constructs and none requiring revision surgery. There were 3 cases of patella subluxation/tilt on the Merchant radiographs, one of which include a fracture of the patella component that was revised as described above. The remaining 2 patients had preoperative valgus knees and were functioning well with no clinical indication for revision. For the subgroup of patients with less than 10 years of follow-up, there were 2 instances of

Cruciate-Retaining in TKA ! Kubiak et al 369

tibial radiolucencies. Both of these occurred in the infected knees, and both knees underwent 2-stage revision for the infection. There was 1 case of patella radiolucency in a cementless patella that did not require revision. There were 4 instances of patella subluxation/tilt, all in preoperative valgus knees, and none requiring revision. There was 1 patella dislocation that was revised as described above.

Discussion Significant deformity has been reported as a contraindication to cruciate-retaining TKA. The senior author exclusively used a cruciate-retaining design during the time of this review. We reviewed the minimum 10-year results of 111 TKAs performed in 93 patients with a preoperative coronal plane deformity of equal to or greater than 108 of varus or equal to or greater than 208 of valgus. We identified very good clinical results and 10-year revision-free survivorship of 93% (95% CI, 87%98%). Most of the reoperations were for infection or patella-related problems. In summary, we found that the clinical and radiographic success rate using such PCL-retaining designs was very successful with only one revision for significant osteolysis and none for instability or loosening. Several authors have discouraged the use of PCLretaining TKA in patients with significant preoperative deformity. Laskin [2] reported on 111 TKAs with fixed preoperative varus deformity (or combined varus and flexion contracture) of at least 158 in whom a PCL-retaining TKA was used. He compared these results to 50 TKAs with similar deformities treated with a posterior stabilized prosthesis. He found a greater incidence of pain, radiolucencies, reduced range of motion, and an increased revision rate in the PCL retained group [2]. He concluded that knees with such deformity should be treated with a posterior stabilized TKA. In contrast, our results show the use of cruciateretaining TKA in patients with large varus or valgus deformity can result in excellent clinical results and survivorship, with only 2 of 64 patients requiring a revision surgery for these findings at long-term follow-up. Stern et al [7] reported on 134 TKAs performed in patients with at least 108 of anatomic valgus preoperatively. A variety of prosthetic designs were used, and they recommended the use of a design that would allow conversion to a more constrained construct should instability progress [7]. We found no instances of progressive ligamentous laxity and no need for conversion to constrained knee designs at 10-year follow-up.

Elkus et al [3] recently reported on 490 consecutive knees with at least 108 of valgus preoperatively using a posterior stabilized TKA and identified 3 revisions (infection, polyethylene wear, and patellar loosening) with otherwise excellent clinical results at a minimum 5-year follow-up. Others have reported their success with the use of PCL-retaining TKA in a variety of patient populations. Scott and Volatile [8] reported their 12-year experience with PCL-retaining TKA and reported that substitution for the PCL was required in only 4 knees out of over 800. Each of these was in patients with greater than 308 of preoperative deformity [8]. Whiteside [9] reported on 135 TKAs with a mean preoperative valgus deformity of 168 using a PCLretaining design with 3 that developed late posterior instability (1 required revision). He concluded that rarely a posterior stabilized implant is needed in severe deformity [9]. Karachalios et al [10] reported on 51 knees with at least 208 of preoperative deformity using a PCL-retaining TKA at a mean of 5.5 years of follow-up and found comparable results to that found in bundeformedQ knees with the exception of patellofemoral malalignment. Teeny et al [1] compared 27 knees with a preoperative varus deformity of at least 208 with 40 knees with less than 58 of deformity. They used a PCL-retaining TKA in all patients and identified the need for PCL recession in less than half of the cases. Clinical results were slightly inferior in the deformed group (89 vs 92) [1]. Krackow et al [11] reported on 99 TKAs with preoperative significant valgus alignment using a PCL-retaining TKA and found 90% good and excellent results at a minimum of 2-year follow-up. There is some controversy that PCL recession (necessary in 42 of 111 knees in this study) essentially renders the PCL incompetent and should be addressed as such. Our clinical results show no evidence of late PCL insufficiency in the long-term follow-up of these knees requiring recession. Worland et al [12] have also shown that patients who underwent simultaneous bilateral CR TKA with PCL recession on only one side had no increased laxity in the recessed knee on KT-1000 testing at a mean of 4 years follow-up. Several sources of potential bias are present in this retrospective study. Choice of implant and decisions regarding soft-tissue release were subjective decisions made by the surgeon based on intraoperative findings. This study suffers from problems inherent in a retrospective review. Preand postoperative alignment was measured from short-standing AP knee radiographs. These radiographs have been shown to have a discrepancy in measurement versus full-limb radiographs [13].

370 The Journal of Arthroplasty Vol. 23 No. 3 April 2008 Using the same type of radiograph for pre- and postoperative assessment should limit any error in measuring alignment. Finally, there was group of patients who had absent (3), inadequate (1), or sacrificed (7) PCLs according to the operative reports. These patients had no significantly worse clinical scores or increased need for revision with the use of a more constrained polyethylene liner. Presently, the senior author’s only indication for a posterior stabilized knee arthroplasty is complete absence of the PCL. The use of PCL-retaining TKA in patients with significant coronal plane deformity remains controversial. The advantages of retaining the PCL include its role as a secondary restraint to varus or valgus stresses, the avoidance of postcam dislocation, the avoidance of potential postwear, and the preservation of the notch region and tibial metaphyseal bone that is removed during preparation of the PS femoral component and stemmed tibial component. For these reasons, the senior author performed exclusively CR TKA during this period. We found, at a minimum of 10 years follow-up, very good clinical and radiographic results with a 93% (95% CI, 87%98%) revision-free survivorship at 10 years and no revisions for instability or loosening. We continue to use primarily PCL-retaining TKAs in patients with significant deformity unless the PCL is found to be severely attenuated or absent.

References [1] Teeny SM, Krackow KA, Hungerford DS, et al. Primary total knee arthroplasty in patients with severe varus deformity. A comparative study. Clin Orthop Relat Res 1991;19.

[2] Laskin RS. The Insall Award. Total knee replacement with posterior cruciate ligament retention in patients with a fixed varus deformity. Clin Orthop Relat Res 1996;29. [3] Elkus M, Ranawat CS, Rasquinha VJ, et al. Total knee arthroplasty for severe valgus deformity. Five to fourteen-year follow-up. J Bone Joint Surg 2004;86-A:2671. [4] WhiteJr RE, Allman JK, Trauger JA, et al. Clinical comparison of the midvastus and medial parapatellar surgical approaches. Clin Orthop Relat Res 1999;117. [5] Archibeck MJ, Berger RA, Barden RM, et al. Posterior cruciate ligament–retaining total knee arthroplasty in patients with rheumatoid arthritis. J Bone Joint Surg 2001;83-A:1231. [6] Ewald FC. The Knee Society total knee arthroplasty roentgenographic evaluation and scoring system. Clin Orthop Relat Res 1989;9. [7] Stern SH, Moeckel BH, Insall JN. Total knee arthroplasty in valgus knees. Clin Orthop Relat Res 1991;5. [8] Scott RD, Volatile TB. Twelve years’ experience with posterior cruciate-retaining total knee arthroplasty. Clin Orthop Relat Res 1986;100. [9] Whiteside LA. Correction of ligament and bone defects in total arthroplasty of the severely valgus knee. Clin Orthop Relat Res 1993;234. [10] Karachalios T, Sarangi PP, Newman JH. Severe varus and valgus deformities treated by total knee arthroplasty. J Bone Joint Surg Br 1994;76:938. [11] Krackow KA, Jones MM, Teeny SM, et al. Primary total knee arthroplasty in patients with fixed valgus deformity. Clin Orthop Relat Res 1991;9. [12] Worland RL, Jessup DE, Johnson J. Posterior cruciate recession in total knee arthroplasty. J Arthroplasty 1997;12:70. [13] Petersen TL, Engh GA. Radiographic assessment of knee alignment after total knee arthroplasty. J Arthroplasty 1988;3:67