Weight bearing versus conventional CT for the measurement of patellar alignment and stability in patients after surgical treatment for patellar recurrent dislocation

Purpose To compare weight-bearing cone-beam computer tomography (CBCT) and conventional computer tomography (CT)-based measurements of patellofemoral alignment and stability in patients surgically treated for recurrent patellar dislocation. These scans implied respectively single-leg up-right posture, the knee flexed, and lower limb muscles activation, versus supine position with the knee extended. Methods A total of 17 patients (11 males/6 females) after surgical reconstruction with fascia lata allograft for recurrent patellofemoral dislocation were analyzed at 60-month follow-up. Tilt and congruence angles and tibial tuberosity–trochlear groove (TT-TG) offset were measured on images obtained from CBCT and conventional CT scans by three independent and expert radiologists. Paired t tests were performed to compare measurements obtained from the two scans. Inter-rater reliability was assessed using a two-way mixed-effects model intra-class correlation coefficient (ICC). Results Only TT-TG offset was found significantly smaller (p < 0.001) in CBCT (mean 9.9 ± 5.3 mm) than in conventional CT (mean 15.9 ± 4.9 mm) scans. ICC for tilt and congruence angles and for TT-TG offset ranged between 0.80–0.94 with measurements in CBCT scans, between 0.52 and0.78 in conventional CT. Conclusion In patients surgically treated for recurrent patellar dislocation, TT-TG offset was found overestimated with conventional CT. All measurements of patellofemoral stability and alignment were found more consistent when obtained with weight-bearing CBCT compared to conventional CT.

Examining Neuromuscular Control of the Vastus Medialis Oblique and Vastus Lateralis Muscles During Fundamental Dance Movements

Elite dancers have a higher rate of injury than college athletes. This may be due, in part, to improper alignment during dance movements. Electromyography (EMG) can be an important indicator of such activity. This study aimed to examine how turnout (maximal hip external rotation) impacts activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles during fundamental dance movements. Thirty female collegiate dancers were recruited from intermediate and advanced ballet and modern technique classes. Surface EMG was used to examine activation of the VMO and VL during maximal isokinetic knee extension in demi-pliés and sautés in parallel and turned-out positions. The mean VMO:VL ratio was determined as a percentage of the highest repetition of maximal extension. The ratio was significantly lower during parallel sautés (0.921 ± 0.258) in comparison to turned-out sautés (1.008 ± 0.384; p = 0.033) and parallel pliés (1.185 ± 0.509; p = 0.002). No significant relationships were found between the VMO:VL ratio and injury history or predominant style of dance. Further investigation is warranted to examine the relationships between VMO:VL activation, patellofemoral alignment, and risk of pathology during simple and complex dance movements.

Clinical findings in patellofemoral osteoarthritis compared to individually-matched controls: a pilot study

ObjectiveTo explore clinical characteristics in individuals with patellofemoral osteoarthritis (PFOA) compared to individually-matched asymptomatic controls. We also explored associations between functional performance and patient-reported symptoms with patellofemoral alignment.MethodsWe assessed 15 individuals with PFOA and 15 individually-matched asymptomatic controls. In addition to physical examination and patient-reported questionnaires, we evaluated functional performance, lower extremity strength and range of motion, and patellar alignment (using MRI). We analysed group differences with Wilcoxon’s matched-pairs signed rank tests, and within-group associations with Spearman’s rank correlations.ResultsWe included 24 (80%) women with median (IQR) age of 56 (9) years and BMI of 22.8 (5.9) kg/m2. Individuals with PFOA reported lower quality of life (8/100 points lower EQ-5D-5L, p=0.02), and performed worse on two functional tests: repeated one-leg rises (median 16 fewer rises, p=0.04) and timed stair climb (1.2 s slower, p=0.03). There were no differences in strength tests performed or range of motion. Patellar proximal translation correlated with worse functional performance and worse patient-reported pain, function and self-efficacy, while lateral translation and lateral tilt correlated with worse knee-related quality of life (Spearman’s r ranging from 0.5 to 0.7).ConclusionFunctional performance was worse in individuals with PFOA, despite those individuals having no significant differences on lower extremity strength testing. Patellofemoral alignment was associated with worse functional performance as well as worse patient-reported outcomes, and it may represent one mechanism underpinning PFOA-related symptoms.

Patellofemoral Arthroplasty Improves Patellofemoral Alignment in Patients with Patellofemoral Osteoarthritis with Trochlear Dysplasia

The impact of trochlear dysplasia on patellofemoral arthroplasty (PFA) has rarely been reported in the literature. The purpose of this study was to explore the effectiveness of PFA in patients with patellofemoral osteoarthritis (PFOA) associated with trochlear dysplasia. From January 2014 to March 2018, 35 patients with PFOA and trochlear dysplasia (29 females and 6 males), underwent PFA, were included in the present retrospective study. Radiological measurements including the patellar tilt (PT), congruence angle (CA), Blackburne–Peel ratio (BPR), tibial tuberosity–trochlear groove (TT–TG) distance, and lateral trochlear inclination (LTI) were assessed pre- and postoperatively to evaluate the changes in patellofemoral alignment. The patient-reported functional outcome was assessed using the Oxford Knee Score. The mean follow-up time was 24 months (range, 18–42 months). The intraclass correlation coefficients were excellent for all measurements. The patellofemoral alignment and knee function were significantly improved postoperatively. The PT decreased from 23.3 ± 6.3 degrees preoperatively to 6.4 ± 2.3 degrees postoperatively (p < 0.001). The CA decreased from 32.3 ± 8.6 degrees preoperatively to 10.2 ± 3.6 degrees postoperatively (p < 0.001). The lateral trochlear inclination increased from 8.3 ± 4.1 degrees preoperatively to 16.0 ± 1.2 degrees postoperatively (p < 0.001). The TT–TG distance decreased from 18.2 ± 3.8 mm preoperatively to 11.5 ± 3.3 mm postoperatively (p < 0.001). The BPR did not significantly change postoperatively (p = 0.390). The average Oxford Knee Score improved from 19.5 preoperatively to 29.2 at 6 months postoperatively (p < 0.001), 37.9 at 1 year postoperatively (p < 0.001), and 39.1 at final follow-up (p < 0.001). No patient developed patellofemoral malalignment or prosthesis loosening during short-term follow-up. PFA achieved favorable therapeutic results in patients with PFOA associated with trochlear dysplasia.