Patellar component size effects patellar tilt in total knee arthroplasty with patellar resurfacing.

PURPOSE: Patellar component positioning and patellofemoral kinematics are of great importance in total knee arthroplasty (TKA). The factors influencing patellar tilt are femoral rotation and lateral patellar release. However, the effect of patellar component size remains unknown. The aim of this study was to evaluate the intra-operative risk factors for patellar tilt, particularly the effect of the patellar component size. The hypothesis was that increasing the patellar component size would reduce the risk of patellar tilt. METHODS: 878 primary TKAs with patellar resurfacing were included between January 2015 and October 2018. Analysis was performed at 1-year postoperatively on patients categorized into two groups: patellar tilt (PT) and no patellar tilt (NPT). A multivariate analysis was performed for the effect of patellar component size, femoral rotation, femoral overbuilding, patellar thickness and lateral release on patellar tilt risk. Secondary analysis was performed for any difference in clinical outcomes and revision rates between groups. RESULTS: Multivariate analysis showed that increasing the patellar component size decreased the risk of patellar tilt by 37% (p < 0.001). Placing the femoral component at 3° of external rotation decreased the risk of patellar tilt by 67% (p < 0.001). Secondary analysis showed better clinical outcomes in the NPT group, especially regarding global satisfaction, and KSS objective and subjective scores. The revision for any cause was less in the NPT group (p = 0.019). The cause for TKA revision was related to the patellar in 11% of cases in the NPT group and 65% in the PT group (p < 0.001). CONCLUSION: Increased patellar component size and positioning the femoral component in external rotation decreases the risk of patellar tilt, improves clinical outcomes and decreases the rate of surgical revision. LEVEL OF EVIDENCE: III.

Patellar morphology is different in patellofemoral instability: An MRI comparative case-control study.

PURPOSE: Although patellofemoral instability (PFI) affects both femoral and patellar compartments, literature provided little attention for the patellar morphology contribution on PFI. This study evaluates the patellar morphology patterns on MRI to establish their contribution in PFI. METHODS: This study retrospectively analyzes patellar MRI and X-ray measurements performed between 2018 and 2022. 50 knees with recurrent patellar dislocation were matched with 50 matched knees of ACL-reconstruction candidates with no history of patellar dislocation based on age and gender. Caton-Deschamps' index, Wiberg's patellar morphotype, Dejour's trochlear dysplasia classification, sagittal patellofemoral engagement index and additional patellar cartilage and bone parameters and their relative ratio measurements were assessed in both groups. RESULTS: Study patients present differences in patellar morphology; a wider lateral facet (p = 0,019) and a narrower medial facet compared to the control group (p < 0,001). The subchondral patellar crest is medialized compared to the control group (p < 0,001). The cartilaginous crest measurements of the patella were not significantly different in both groups yet PFI group presents a wider Wiberg angle (p < 0,001), thus a flatter patella, compared to the control group. CONCLUSION: The patella in PFI patients presents a larger lateral facet, a narrower medial facet, a flatter surface and a medialized patellar crest compared with the control group. In PFI, a rather medial patellar crest might predispose towards a greater patellar tilt and destabilize the already compromised patellar-trochlear groove congruence. PFI is a multifactorial disease and both trochlea and patella play a role in its manifestation, thus, literature should address patellar morphotype contribution in patellofemoral instability. LEVEL OF EVIDENCE: Level III.

Does meniscal repair impact muscle strength following ACL reconstruction?

PURPOSE: Meniscal lesions are commonly associated with anterior cruciate ligament (ACL) rupture. Meniscal repair, when possible, is widely accepted as the standard of care. Despite advancements in surgical and rehabilitation techniques, meniscal repair may impact muscle recovery when performed in conjunction with ACL reconstruction. The objective of this study was to explore if meniscal repairs in the context of ACL reconstruction affected muscle recovery compared to isolated ACL reconstruction. METHODS: Fifty-nine patients with isolated ACL reconstruction were compared to 35 patients with ACL reconstruction with an associated meniscal repair. All ACL reconstructions were performed using hamstring grafts with screw-interference graft fixation. Isokinetic muscle testing was performed between six and eight months of follow-up. Muscle recovery between both groups was compared. A further subgroup analysis was performed to compare muscle recovery function of gender and meniscal tear location. Tegner scores were assessed at six months' follow-up. RESULTS: No significant differences were found between the two groups regarding muscle recovery. No difference in muscle recovery was found concerning gender. Lesion of both menisci significantly increased the deficit of hamstrings muscular strength at 60°/s compared to a lesion of one meniscus (26.7% ± 15.2 vs. 18.1% ± 13.5, p = 0.018) and in eccentric test (32.4% ± 26.2 vs. 18.1% ± 13.5, p = 0.040). No significant differences were found concerning the Tegner score. CONCLUSION: Meniscal repairs performed during an ACL reconstruction do not impact muscle recovery at 6-8 months post-operatively compared to an isolated ACL reconstruction. However, reparations of both menisci appear to impact hamstring muscle recovery negatively. LEVEL OF EVIDENCE: III, Retrospective cohort study.

Adding a modified Lemaire procedure to ACLR in knees with severe rotational knee instability does not compromise isokinetic muscle recovery at the time of return-to-play.

PURPOSE: To determine whether isokinetic muscle recovery following ACLR using a hamstring tendon (HT) would be equivalent (non-inferior) in knees that had high-grade pivot-shift and adjuvant modified Lemaire procedure versus knees that had minimal pivot-shift and no adjuvant modified Lemaire procedure. METHODS: We evaluated 96 consecutive patients that underwent primary ACLR. Nine were excluded because of contralateral knee injury, and of the remaining 87, ACLR was performed stand-alone in 52 (Reference group), and with a Lemaire procedure in 35 (Lemaire group) who had high-grade pivot-shift, age < 18, or genu recurvatum > 20°. At 6 months, isokinetic tests were performed at 240°/s and 90°/s to calculate strength deficits of hamstrings (H) and quadriceps (Q). At 8 months, patients were evaluated using IKDC, Lysholm, and Tegner scores. RESULTS: Compared to the Reference group, the Lemaire group were younger (23.0 ± 2.5 vs 34.2 ± 10.5, p = 0.021) with a greater proportion of males (80% vs 56%, p < 0.001). The Lemaire group had no complications, but the Reference group had one graft failure and one cyclops syndrome. Strength deficits at 240°/s and at 90°/s were similar in both groups, but mixed H/Q ratios were lower for the Lemaire group (1.02 ± 0.19 vs 1.14 ± 0.24, p = 0.011). IKDC and Lysholm scores were similar in both groups, but Tegner scores were higher in the Lemaire group (median, 6.5 vs 6.0, p = 0.024). CONCLUSIONS: ACLR with a modified Lemaire procedure for knees with rotational instability grants equivalent isokinetic muscle recovery as stand-alone ACLR in knees with no rotational instability. For ACL-deficient knees with high-grade pivot-shift, a Lemaire procedure restores rotational stability without compromising isokinetic muscle recovery. STUDY DESIGN: Level III, comparative study.