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.

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.

Accepted landmarks for determining rotation include the posterior condyles, Whiteside’s line, arbitrary 3-4° of external rotation, and transepicondylar axis (TEA). All methods require anatomical identification, which may be variable.

The purpose of this study was to radiologically evaluate femoral component rotation (CT analysis) based on a method that references to the tibial axis and balanced flexion-tension.

Methods: CT scans of 38 randomly selected TKA were evaluated to determine femoral component positioning. Spiral CT scans of the femoral epicondylar region with eight 4mm cuts were performed to accurately identify medial and lateral epicondyles. Rotational alignment was measured in relation to the transepicondylar axis using CT-implemented software by two independent radiologists.

Results: Femoral component rotation ranged from 4° internal rotation to 5° external rotation with a mean of 0.0° = parallel to the TEA. All 38 cases had satisfactory clinical results, range of motion of over 90°, and showed perfect patello-femoral tracking and patellar congruency.

Conclusions: Femoral rotation position based on tibial axis and balanced flexion tension is patient specific, reproducible and results in predictable patella tracking. CT analysis in this study confirms that the tibial axis method produces a consistent femoral component positioning that relates accurately to the TEA. Tibial axis method avoids the need for arbitrary landmark identification, placing the femoral component predictably in an optimum position in relation to the tibia and patella.

The low contact stress and self-aligning properties of mobile bearing total knee replacements (TKR) make them an increasingly popular implant choice worldwide. Two variations on the mobile bearing knee concept have been commonly adopted: systems that retain the posterior cruciate ligament (PCL) and provide free rotation and translation (RT) of the mobile bearing, and systems that sacrifice the PCL and provide for rotation only (RO) motion of the mobile bearing. The purpose of this study was to evaluate the in vivo kinematics of these two types of mobile bearing TKR during gait, stair, and two deep knee flexion activities.

Twelve patients (6 RT, 6 RO) with unilateral mobile bearing knee arthroplasty and excellent functional outcomes at least one year after TKR were studied. Fluoroscopic images of the knee were acquired as patients walked on a treadmill, ascended a step, performed a deep knee bend, and knelt to maximum flexion. Knee kinematics were derived from CAD model based shape matching techniques.

The RT knees exhibited greater posterior translation of the femur on the tibia during early stance in gait (RT: 5mm vs. RO: 2mm) and during knee extension during stair ascent (RT: 5mm vs. RO: 1.5mm). There were no differences between the two groups in the flexion angles achieved during deep knee bend or kneeling.

Although there were no significant clinical or functional differences in these patients, the RO knees exhibited smaller tibio-femoral translations and less intersubject variability in knee kinematics during dynamic weight-bearing activities.

The purpose of this study was to analyse and to recommend solutions for early complications with a new total knee mobile bearing device, that promises a logical synthesis of combined A/P translation and rotation ability, but has shown early surgical technique related complications.

Materials and Methods: There were 244 Low Contact Stress (LCS) A/P glide total knee replacements (TKA) performed in the time between 1995 and 1999. Mean age was 67.2 years (range: 53-83). Mean follow-up was 16.5 months (range: 1-51). There was an unusual high incidence of anterior knee pain in this group compared with excellent results utilising rotating platform LCS TKA in this centre. Diagnostic evaluation included radiographs, arthroscopical evaluation, and positron emission tomography in five selected cases.

Results: There were 11 (4.5%) cases with Hoffa fatpad impingement, progressive ligament instability in 5 (2.0%) cases, arthrofibrosis in 4 (1.6%) cases, one malposition of tibial component, and one proximal tibial AVN. Five PET 18F-FDG scans prior to revision surgery revealed increased up-take correlated with intraoperative findings of fatpad fibrosis and/or necrosis.

Conclusion: The LCS A/P glide mobile bearing TKA has theoretical advantages over both meniscal and rotating mobile bearing knee designs. Early occurrence of Hoffa fatpad impingement was caused by surgical mal-technique in this centre that usually retains the vast majority of the fat pad. Revision surgery revealed evidence of impingement and all cases revealed clinical improved after partial excision of the fatpad. We, therefore, recommend partial to total excision of the Hoffa fat pad for utilisation of the A/P glide prosthesis.

The purpose of this study was to analyse a potential correlation of arthrofibrosis (AF) and femoral rotational mal-alignment in total knee arthroplasty (TKA). We hypothesized an increased internal mal-rotation of the femoral component leading to unphysiological kinematic motion of the arthroplastic knee joint. These repetitive microtrauma may then induce increased synovial hyperplasia leading to arthrofibrosis. Arthrofibrosis is an ill-defined entity that results in unsatisfactory outcome following TKA. Biological and mechanical factors have been suggested as etiology, but specific causes have not been identified.

Methods: From a cohort of 3058 mobile bearing TKA 44 (1.4%) cases were diagnosed with arthrofibrosis, of which 38 (86%) cases underwent clinical examination and CT investigation to determine femoral component rotation taking the transepicondylar (TEA) axis as reference point. A control group with 38 well functioning TKA was compared.

Results: Increased internal mal-rotation of the femoral component of 5.0° in the AF group (reference to the TEA) was highly significant (p < 0.001) ranging from 10°IR to 1°ER compared with the control group (0.0° parallel to TEA, 4°IR to 5°ER). Men younger than average for index TKA in this center with a decreased BMI, previous knee surgery (particularly correcting osteoto-mies), poliomyelitis, and OA had an increased risk of developing arthrofibrosis. PCL retaining or sacrificing, patella resurfacing or retaining had no increased prevalence for AF. Rheumatoid patients had a decreased risk of developing arthrofibrosis .

Conclusion: The correlation of AF to femoral component internal mal-rotation was statistically significant (p < 0.001). These results confirm that unphysiological kinematics in TKA appear to be a major etiopathological factor for arthrofibrosis (AF). In this study femoral component internal mal-rotation has shown to be a significant risk factor in the development of arthrofibrosis. We, therefore, recommend consideration of early CT evaluation in cases with AF and, when internally mal-rotated, revision of the femoral component.

This study has been cleared by the Ethical Committee, University of Zurich, Switzerland.

Correction of fixed valgus is a challenge in primary TKA. Achieving patello-femoral and femoral-tibial stability requires superficial/deep lateral side releases if non-constrained prostheses are utilized. The medial approach has disadvantages with more reported complications. The direct lateral approach, with/without tubercle osteotomy, is an approach option utilized in two reporting centers.

Methods: 255 valgus TKAs with 5- to15-year follow-up were reviewed. Demographics included 91% females, 15% rheumatoid, mean age 69. Prostheses utilized were LCS mobile-bearing (meniscal PCL-retaining/rotating PCL-sacrificing). Patella was non-resurfaced in 90%; cementless fixation in 86%. The direct lateral approach with similar lengthening techniques was used with tubercle osteotomy in one center and osteo-periosteal joint exposure in another.

Results: Good/excellent 91%, modified HSS score improvement 57 to 85. Deformity (12) improved < 8 to 12 points (> 15o valgus to < 5o valgus). ROM improved from mean 11o/97o to 1/110o latest. Technical/prosthetic-related complications included: 7 bearing failures (5 meniscal, 2 rotating platform), 2 aseptic loosenings (tibial), 1 patella ligament rupture and 2 screw loosenings in the osteotomy group, 1 patella re-dislocation in a 75-year-old female with dislocation since age 15 (non-osteotomy group), 2 infections, and 1 re-operation for arthrofibrosis .

Discussion/Conclusion: Valgus TKA using LCS move-able bearings implanted via a direct lateral approach are highly successful regarding stability and patella tracking. Failures correlate with inadequate/de-stabilizing releases and meniscal PCL-retaining prostheses. Rotating bearings allow for better stability and self-adjustment of common mal-rotation variables. The lateral approach allows for direct (step-wise) lengthening releases, improved patellar tracking, and precise gap balancing.

Aims: The purpose of this study was to evaluate the clinical outcome of 457 LCS mobile bearing TKA from one centre. Methods: From a cohort of over 3.500 mobile bearing TKA in one large center, 457 cases were performed more than 10 years ago (mean 11 years). Drop-out were 63 (13.8%) cases, 128 patients were known to have died and 63 (13.2%) cases could not be included leaving 86.2% that entered the study. Patient demographics included 76% females and 8% rheumatoids. There were 275 (60%) meniscal bearing and 182 rotating platform design components. The patella was resurfaced in 95 (21%) cases. Results: Preoperative KSS scores improved from a mean of 84 to 157 points and mean range of motion from 97 to 110 degrees postoperatively. Clinical scores were excellent or good in 88%, moderate in 10% and poor in 2%. Kaplan Meier survival analysis was 96.9% after a mean of 11 years taking any revision into account. Worst track record were polyethylene meniscal bearings with 91.2% and best the femoral component with 99.8% after a mean of 11 years. Other complications will be listed in depth. Conclusion: Best track record was noted with the all cruciate sacrificing rotating bearing device and worst with the ACL and PCL retaining meniscal bearing device. Patella also jeopardized the long-term results

Aims: The purpose of this study was to determine whether internal malrotation of the femoral component is associated with arthroþbrosis in TKA. We hypothesized arthroþbrosis may be triggered by a combination of nonphysiological kinematics (femoral component internal rotation) and a tight medial compartment. Methods: From a consecutive cohort of 3058 mobile bearing TKA forty-four (1.4%) cases were diagnosed as having arthroþbrosis, of which thirty-eight (86%) cases could be recruited. Thirty-eight patients with a well functioning TKA served as matched controls. Evaluation included CT investigation to determine femoral component rotation with reference to the transepicondylar axis (TEA). Results: Femoral components in the AF group were signiþcantly (p< 0.00001) internally mal-rotated by a mean of 4.7 degrees ranging from ten degrees internal rotation (IR) to one degree external rotation (ER). Mean femoral rotational in the control group was parallel (0.3 degrees IR) to the TEA (six degrees IR to four degrees ER). Arthroþbrosis was not associated with age, gender, body-mass-index, or preoperative diagnosis. Conclusions: There is a highly signiþcant association between arthroþbrosis in TKA and internal mal-rotation of the femoral component. On the base of these results it was hypothesized that non-physiological kinematics in TKA with mal-aligned femoral components inßuence and/or trigger arthroþbrosis in TKA. In TKA with arthroþbrosis, we now consider femoral CT evaluation with the view to surgically rebalancing the ßexion gap and realigning the femoral component, when internal mal-rotation is conþrmed.

Aims: This study evaluated the outcome of bilateral hip and knee arthroplasty in the same patient with special regards to schedule planning, postoperative complications and follow-up. Methods: Since 1985 more than 6000 THA and 5500 TKA were implanted in one large center, of which 8% were rheumatoid patients. Quadruple THA and TKA were performed in a total of 58 (0.1%) of which 88% were RA. Mean follow-up of knees was 8.5 years (1–17), of hips 9.5 years (1–18). On average 67% of implants were uncemented. In 21% of the cases all four prostheses were implanted within one year and over 50% within five years. Results: Taking revision of components as failure there were three infections (CLS hip, GSB and LCS knee), two aseptic loosenings (Endler cup, GSB knee), two recurrent hip dislocations, three knee bearing exchanges (LCS, INNEX), and four patella component removal (GSB, PCA). Discussion and Conclusion: Quadruple arthroplasty in the lower extremity did not show an increased failure rate compared with single arthroplasty in this center. The results of this study support the indication for quadruple procedure with early postoperative rehabilitation and full weight bearing. Data suggest a procedure with hips before knees and at least three weeks between any arthroplasty operations.