BACKGROUND

UKA is functionally superior to TKA, with kinematics similar to native knees, nevertheless, UKA implants are used in less than 10% of cases. While advantages of UKA are recognized, ACL-deficiency is generally considered a contraindication. The hypothesis of this study was that fix bearing UKA in ACL-deficient knees, with appropriate adaptation of implant placement, would result in similar kinematic trends to conventional UKA with an intact ACL.

Introduction

Patellofemoral complications remain a very common post-operative problem in association with total knee arthoplasty (TKA). As malrotation of the femoral component is often considered crucial for the outcome, we analyzed absolute rotational femoral alignment in relation to patellar tracking pre- and postoperatively and matched the results with the two year functional outcome.

Background

Second-generation high-carbon CoCrMo-alloy metal-on-metal total hip arthroplasty (THA) was introduced in the late 1980s following reports of early loosening, impingement, pronounced wear, and hypersensitivity in the first-generation metal-on-metal articulations. There has been inconsistent data that specifically addresses the clinical performance and longevity of second-generation metal-on-metal THA. The purpose of this study was to evaluate the survival of second-generation metal-on-metal primary THA and to assess the influence of demographic factors on implant survival in a large patient cohort.

Introduction: Rotational alignment of the femoral component is widely believed to be crucial for the ultimate success of total knee arthroplasty (TKA). However there is a paucity of normative data on femoral component rotation in ‘perfect’ TKA.

Methods: Femoral component rotation in well-functioning TKA was assessed by means of axial radiography as described by Kanekasu et al. Well-functioning TKA were defined by three criteria at 5-year follow-up:

Knee Society objective and functional score of 190 or above

Thirty TKA of 29 patients (9 male, 20 female) with a median age of 70 years (range, 31–87) at time of surgery fulfilled the study criteria. All TKA were implanted at a single high-volume joint replacement center in 2002. In all cases both the condylar twist angle (CTA) using the clinical epicondylar axis (CEA) and the posterior condylar angle (PCA) using the surgical epicondylar axis (SEA) were used to assess rotational alignment of the femoral component.

Results: Overall, the mean CTA was 3.6+−3.5° of internal rotation (IR) (range, 4.1° of external rotation (ER) to 8.6° of IR) for the femoral component. For females, the CTA had a mean value of 4 +/−3.7° of IR (range, 7.6° of IR to 4.1° of ER) compared to 2.3 +/−3° of IR (range, 5.3° of IR to 2.5° of ER) in males. Overall, the mean PCA was 1.5 +/−3.5° of ER (range, 8.4° of ER to 5.1° of IR). In females, the mean PCA was 1 +/−3.9° ER (range, 2.3° of IR to 5.8° of ER) compared to 2.8 +/−2° ER (range, 0.4° of ER to 5.7° of ER) in males. The mean angle between CEA and SEA was overall 5.1 +/−1.8° (range, 3.3° to 9.1°), in females 5.1 +/−1.6° (range, 3.5° to 9.0°) compared to 5.0 +/−2.4° (range, 3.2° to 9.1°) in males.

Conclusion: Well-functioning TKA demonstrated a highly variable rotational alignment of the femoral component ranging from excessive external rotation to excessive internal rotation. These findings challenge current reference values for optimal femoral component rotation.

Introduction: Since the introduction of the Zimmer Innex UCOR (Ultra COgruent Rotating) mobile bearing total knee arthroplasty (TKA) system in 1999, there were close to 3000 primary TKAs performed at our institution utilizing this implant. We report on the first 396 5-year follow-up results and overall revisions in our total collective.

Methods: Between 1999 and 2006 there were 2734 primary Innex UCOR TKA performed (1748 female/987 male) at the Schulthess Clinic, Zurich. Primary diagnosis leading to TKA were OA (2462 – 90%), RA (144 – 5.3%), posttraumatic arthritis (65, 2.4%), necrosis (50, 1.8%) and misc causes (13 – 0.5%). The mean age of the females patients was 69y (33y – 92y), and 68y (31y – 93y) in the male population. To date 396 knees underwent clinical and radiological follow-up at 5 years (mean 5y 0m, range 4y 1m – 7y 2m), with 5% of the patients being lost to follow-up. Scoring was done, using the Knee Society Score (KSS). All patients had a full leg radiograph pre-operatively as well as at follow-up.

Results: Total KSS improved from 106.5 (6 – 184) pre-operatively to 179.5 (80 – 200) at follow-up, the knee score from 42.2 (2–93) to 92.1 (37 – 100), the function score from 64.3 (0–100) to 87.4 (10–100) respectively. The pain score increased from 17.7 (0–50) to 47.5 (20–50, 50 points maximum). ROM pre-operatively was 104.6° (0–145) and reached 117.2° at follow-up (55–145). Subjective evaluation by the patient at 5 years was excellent and good in 91%, fair in 8% and taxed poor by 1% of the patients. 95% of full leg radiographs showed a femorotibial angle of 182°–188°, 3% were < 182° (varus), 2% > 188° (valgus). Overall revision rate (95 of 2735) was 3.5%, 1.1% for infections and 1% for anterior knee pain and/or patella pathology. 0.6% were revised for instability, 0.3% for arthrofibrosis, and the remaining 0.5% for various problems.

Conclusion: These promising 5 year observations with the Innex UCOR mobile bearing TKA system suggest favorable overall midterm results. Further longer term follow-up evaluations are scheduled while 5 year follow-ups are ongoing, allowing for continuing reports on long-term performance.

Introduction: Stiffness after primary total knee arthroplasty (TKA) is a severe complication that has been associated with excessive internal rotation of the femoral component.

Methods: Between 2001 and 2004, 18 patients with 18 well-fixed, aseptic primary TKA underwent revision TKA at a single high-volume joint replacement center for stiffness in the presence of femoral component mal-rotation. Stiffness was defined as ROM with less than 90° of maximum flexion or a flexion contracture greater than 10°. Femoral component malrotation was defined as a condylar twist angle of more than 4° of internal rotation using CT scans. Following IRB approval, 17 out of 18 patients (median age at time of the index surgery 62.7 years, range 45 to 78; female, n=11; male, n=6) were available for retrospective outcome assessment. The mean time between primary and revision TKA was 3.2 years (range, 9–79 months). At a mean follow-up of 3.3 years (range, 2 to 6), all patients were evaluated clinically using the Knee Society objective and functional scores, and by CT measurement of femoral component rotation. Patients without additional procedures between primary and index revision TKA (group A, n=9) were compared using Student t-testing with those which had undergone additional interventions (group B, n=8).

Results: Five patients had required additional procedures after the index revision TKA including closed manipulation under anesthesia in one case, patellar resurfacing in one case, metal removal after tubercle osteotomy and open debridement in another case, and tibial component revision followed by revision TKA in one case. CT scans after revision TKA revealed correction of femoral component rotation in all but one case from each group. After revision TKA, the mean objective score was overall 73 points, in group A 82 points compared to 63 points in group B (p< 0.001). In group A there were 78% excellent or good results compared to 13% in group B. The mean function score was overall 74 points, 78 points in group A compared to 69 points in group B. There were 67% good or excellent results in group A compared to 12% in group B. Mean flex-ion increased overall from 71 to 92 degrees (p< 0.01), in group A from 61 to 96 degrees (p< 0.01) and in group B from 82 to 89 degrees. Mean flexion contracture was reduced overall from 7 to 4 degrees, in group A from 6 to 3 degrees, and in group B from 8 to 5 degrees. Stiffness persisted in four cases (24%) (group A, n=1; group B, n=3). Satisfaction (VAS 0–100; 100=completely satis-fied) scored overall a mean of 52 points, in group A 57 points and in group B 44 points.

Conclusion: Overall, revision TKA for knee stiffness associated with femoral component internal malrotation resulted in significantly improved knee motion. However, outcome was less predictable in those patients with additional procedures between primary and revision TKA.

Introduction: The purpose was to present a new osteotomy technique (trochleoplasty) and its preliminary results for the treatment of femoral trochlear dysplasia with recurrent patellar dislocation.

Methods: Between 1990 and 2002, 59 knees of 51 patients (mean age 224 years) with recurrent patellar dislocation due to femoral trochlear dysplasia were treated uniformly at a single institution with a new osteotomy technique developed by the senior author. A distally connected osteochondral flake is released from the dysplastic trochlea and refixed after the osseous trochlear groove has been reconstructed. 44 patients with 50 involved knees returned at a mean follow-up of 37 months (range 6 to 139) for a physical examination, assessment of knee pain and function, radiographic examination of the knee, and in selectived cases for CT scan, MR imaging and follow-up knee arthroscopy.

Results: Postoperative complications were limited to hemarthros-1, arthrofibrosis-1, and sudeck‘s disease-1. Postoperatively, no further patellar dislocations were reported. All patients experienced a sensation of significantly improved knee stability resulting in higher levels of activity. Retropatellar pain as found in 34 knees preoperatively was better-24, unchanged-7, worse-6 (3 additional cases) after surgery. Positive apprehension sign, as preoperatively found in all patients, turned negative in all cases. Radiographically, osseous healing of the reconstructed trochlea was noted without evidence of subsequent arthrosis. MRI and knee arthroscopy including histological analysis of osteochondral biopsies did not provide any evidence for osteonecrosis or chondropathia.

Conclusion: Recurrent patellar dislocation due to femoral trochlear dysplasia can be treated successfully using the presented technique of trochleoplasty.