Patella management in total knee arthroplasty remains controversial. Minimizing patella related problems is the main goal in any type of knee arthroplasty. This can be achieved with and without resurfacing. However, patella resurfacing resulted in, at times, catastrophic failures, which increased the popularity of patella non resurfacing, particularly with anatomical femoral groove designs. If patella non resurfacing is to be recommended, clinical outcomes must be equal or better than those of routine patella resurfacing in the specific prosthesis utilized.

From a large cohort of over 6000 TKA five studies were conducted to analyze isokinetic strength, subjective, clinical, and radiographic outcomes as well as histopathological data.

Isokinetic strength, subjective, clinical, and radiographic outcomes favor nonresurfacing in TKA with proper femoral component rotation and conforming patellar groove. Our data indicate that patella subluxation and femoral component malrotation is significantly associated with development of arthrofibrosis.

On the base of our studies we propose specific surgical techniques for optimal patella treatment (patelloplasty) in TKA.

Patellectomized knees often perform poorly with respect to extensor mechanism function. Reconstruction options and literature reports are limited. The purpose of this study was to describe and review bone graft patella reconstruction in TKA.

Material_e_Methods: Since 1990 nine previously patel-lectomized patients underwent cementless Low-Contact-Stress TKA with autologous patella reconstruction. One patient died 5 years post surgery. Mean follow-up was 8.0 years (6 to 12). Autologous bonegraft was taken in five cases from the iliac crest, in two cases from the posterior femoral condyle and in two cases from the opposite patella at time of simultaneous bilateral TKA. Postoperative evaluation included clinical and radiographic analysis and bilateral comparative isokinetic strength measurement at 60 degrees per second (Biodex).

Clinical scores had a mean of 27 points (max: 30) and mean isokinetic extension strength of 71Nm (81 percent) compared with the opposite healthy patella site. One patient with bilateral patellectomy and unilateral patella reconstruction showed a 50 percent increase of strength on the grafted side. Radiographs showed minor signs of neopatella bone resorption, but a maintained leaver arm.

Reconstruction of a neo-patella in TKA with autograft provides marked improvement of isokinetic extensor strength, little evidence of autograft resorption, excellent or good clinical outcome and high patients satisfaction after a mean of 8 years. The results of this study indicate encouraging data for reconstructing a new patella and lever arm in patellectomized knees during primary or revision TKA. Cosmetic improvement in females is another subjective advantage.

The purpose of this prospective and randomized study was to objectively evaluate isokinetic strength, clinical, and radiographical outcome in bilateral TKA using the same prosthesis with and without patella resurfacing.

Bilateral TKA, one with, one without patella resurfacing was performed in 22 osteoarthritic patients, mean age was 68 years using the Low-Contact-Stress prosthesis. Minimum Follow-up was one year. Evaluation included clinical investigation, specific patella scores, radiographic analysis and isokinetic strength measurement of both knee flexion and extension at 60 degrees per second (Biodex). surement at 60 degrees per second (Biodex).

There was no significant clinical score difference, but mean isokinetic strength of knee extension was significantly (p< .0001) stronger in the non-resurfaced patella TKA (40.5 Nm) compared with the resurfaced TKA (38,5 Nm). Flexion was also significantly stronger in the patella non-resurfaced group with 22.4 Nm versus 19.5 Nm in the resurfaced group. Mean lateral deviation was significantly (p< .001) less ideal in the resurfaced group as was postoperative patellofemoral congruent contact (p< .001). However, there was no correlation between lateral patella deviation or congruent contact and iso-kinetic strength.

The results of this study indicate that mean isokinetic strength of both knee flexion and extension was significantly stronger in the non-resurfaced patella TKA. This study provides encouraging data for patella non-resurfacing. However, clinical scores or patient’s preference did not show any difference.

The purpose of this study was to determine whether internal mal-rotation of the femoral component is associated with arthrofibrosis in TKA. Multiple etiological factors have been suggested, but specific causes have not been identified. We hypothesized arthrofibrosis may be triggered by a combination of non-physiological kinematics (femoral component internal rotation) and a tight medial compartment.

From a consecutive cohort of 3058 mobile bearing TKA forty-four (1.4%) cases were diagnosed as having arthrofibrosis, 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 significantly (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). Arthrofibrosis was not associated with age, gender, body-mass-index, or preoperative diagnosis

There is a highly significant association between arthrofibrosis 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 influence and/or trigger arthrofibrosis in TKA.

Introduction/purpose: Cementless femoral fixation in TKA varies regarding philosophy of design, materials, and surgical technique. This study evaluates autograft enhancement with AML (porocoated) stems. Impaction autograft (head reamings) enhances cortico-cancellous fit in canals of different geometry, preserves bone, decreases potential for stress shielding and seals the stem from wear particles.

Materials/methods: Clinical/radiologic evaluation of 110 AML prostheses (proximal/extensive porous-coated) with 4- to 11-year (mean 6.9) follow-up was performed. Demographics included 68 females, 42 males, age 34–90 (mean 66). Diagnoses included OA (86), RA (16), other (8). Key surgical points included: 1) stem matching/sizing to proximal cortical contact; 2) head/neck reaming with acetabular graters; 3) autograft delivery (distal-lateral) prior to partial stem insertion and proximal-medial prior to prosthetic seating.

Results: Femoral stem fixation was successful in 98%. Autograft fill was visualized radiographically within the first 6 weeks. Stem fit-fill ratios were .63 proximally and .73 distally, suggesting that most stems were stabilized via cortico-cancellous bone. The 2 fixation failures (1 stem fracture, 1 aseptic loosening) occurred in large males with undersized stems. Radiologic stability was noted in 95%. There were 6 cases of proximal osteolysis secondary to wear without distal extension, and no lucency > 2mm. Mean subsidence was.6mm. There were 10 acetabular failures secondary to wear/loosening and 1 traumatic neck fracture. There were no infections.

Conclusion: The technique of impaction autograft using femoral head reamings is a biological (osteoinductive-osteoconductive), practical, and simple treatment method to accommodate and fill femoral canal voids frequently encountered in THA. Large, stiff stems (with distal fixation) can be avoided with less risk of technical problems and long-term bone loss secondary to stress shielding. The technique can be utilized, with variation, in any current cementless femoral stem.

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.

Cementless fixation in TKA remains controversial because of less predictable osseointegration and difficulty interpreting fixation interfaces. Radiolucent zone analysis (RLZ) of plain radiographs is the only practical method of evaluating the fixation interface.

Methods: This study evaluated 567 consecutive primary LCS mobile-bearing TKA with in-depth RLZ analysis of all cases by one author (T.K.). Mean follow-up was 5.7 years (2.0-14.9), mean age 69 years (70% females). Diagnosis included 8.3% rheumatoids. The same porocoated femoral and patella components were utilized. Tibial components included a 3-fin (ACL/PCL-retaining) or tapered-cone design (PCL-retaining/substituting). Bone treatment included generous use of autograft: cortico-cancellous struts for slope-off deformities and soft bone, morselized impaction for central zones, slurry to achieve interference fit.

Results: Good/excellent results were 94.7% with 4 fixation failures. Sequential RLZ of six patellar, four femoral, six tibial zones revealed: 1). Minimal femoral/patella lucencies---no failures; 2) Tibial tapered cone (n = 523) had one (0.2%) failure. Lucencies of 1–2 mm (usually isolated) were noted in 2% medial, lateral, posterior and 4% anterior/central zones, all of which remained stable; 3).Tibial 3-fin tibial design (n = 44) had 3 failures (6.8%) with RLZ > 2mm in multiple zones.

Conclusion: Cementless fixation with LCS porocoat pros-thesis was successful in all femoral/patellar and 99% of the tibial-cone design. The 3-fin design had multiple RLZ and a higher failure rate (not recommended). RLZ analysis with plain X-rays (over time) is a practical method of evaluating cementless fixation and correlates with clinical outcomes in our study.

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: Fixed valgus requires lateral releases for stable patellar tracking and gap balancing. Adequate extension space must be achieved without weakening the lateral sleeve. This complication can occur with sub-periosteal femoral LCL/popliteus releases. Distal LCL lengthening and/or lateral epicondylectomy with advancement maintaining soft tissue strength/stability. Methods: 174 valgus TKAs with 5- to 15-year follow-up were reviewed. Demographics included 93% females, 13% rheumatoid, mean age 69. Prostheses utilized were LCS meniscal (30%) and rotating (70%). Fixation was cementless in 86%. The direct lateral approach was used in all cases. Results: Good/excellent results were 91% (HSS scores 54 to 84). Deformity correction mean > 15° to < 5° valgus. Of the failures, 5 were meniscal PCL-retaining (1 malposition, 2 subluxations, 2 wear). Four meniscal and one rotating bearing spin-out were related to inadequate (over/under) concave side balancing, all in early cases with standard femoral sub-periosteal releases. Conclusion: Release of contracted concave side soft tissues, without compromising strength/integrity of the LCL/popliteus complex, is required to achieve stable flexion-extension gap balance and correction of the biomechanical axis in fixed valgus TKA. Improved techniques of lateral side releases that maintain ligament attachments and allow more precise lateral extension gap adjustment have eliminated failures related to soft-tissue imbalance with non-constrained implants. Key technique points of the lateral approach, with emphasis on the deep releases, will be illustrated.

Aims: Correction of fixed valgus is a challenge in primary TKA. The direct lateral approach, with/without tubercle osteotomy, is an approach option utilized in two reporting centers. Methods: 255 valgus TKA 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%. Results: Good/excellent 91%, modified HSS score improvement 57 to 85. Deformity (12) improved < 8 to 12 points (> 15° valgus to < 5° valgus). ROM improved from mean 11°/97° to 1/110° 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. Conclusion: Valgus TKA using LCS moveable 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 (stepwise) lengthening releases, improved patellar tracking, and precise gap balancing.

Aims: Cementless þxation in TKA remains controversial because of less predictable osseointegration and difþculty interpreting þxation interfaces. Methods: This study evaluated 567 consecutive primary LCS mobile-bearing TKA with in-depth RLZ analysis of all cases by one author (T.K.). Mean followup was 5.7 years (2.0-14.9), mean age 69 years (70% females). Diagnosis included 8.3% rheumatoids. The same porocoated femoral and patella components were utilized. Tibial components included a 3-þn (ACL/PCLretaining) or tapered-cone design (PCL-retaining/substituting). Bone treatment included generous use of autograft: cortico-cancellous struts for slope-off deformities and soft bone, morselized impaction for central zones, slurry to achieve interference þt. Results: Good/excellent results were 94.7%. Minimal femoral/patella lucencies; Tibial tapered cone (n = 523) had one (0.2%) failure. Lucencies of 1–2 mm (usually isolated) were noted in 2% medial, lateral, posterior and 4% anterior/central zones, all of which remained stable; 3) Tibial 3-þn tibial design (n = 44) had 3 failures (6.8%) with RLZ > 2mm in multiple zones. Conclusion: Cementless þxation with LCS poro-coat prosthesis was successful in all femoral/patellar and 99% of the tibial-cone design. The 3-þn design had multiple RLZ and a higher failure rate (not recommended).

Patellofemoral problems are a common cause of morbidity and reoperation after total knee arthroplasty. We made a prospective study of 52 patients who had bilateral arthroplasty (104 knees) and in whom the patella was resurfaced on one side and not on the other. A movable-bearing prosthesis with an anatomical femoral groove was implanted on both sides by the same surgeon using an otherwise identical technique. The mean follow-up was 5.24 years (2 to 10). In the 30 available patients (60 knees) there was no difference between the two sides in subjective preference, performance on ascending and descending stairs or the incidence of anterior knee pain. Radiographs showed no differences in prosthetic alignment, femoral condylar height, patellar congruency or joint line position. The use of an appropriate prosthetic design and careful surgical technique can provide equivalent results after knee arthroplasty with or without patellar resurfacing. Given the indications and criteria, which we discuss, retention of the patellar surface is an acceptable option.