Pericapsular Nerve Group Block Leads to Small but Consistent Reductions in Pain Between 18 and 24 Hours Postoperatively in Hip Arthroscopy for Femoroacetabular Impingement Surgery: A Prospective, Randomized Controlled Clinical Trial.

PURPOSE: To investigate whether the use of a pericapsular nerve group (PENG) block would reduce perioperative pain after arthroscopic therapy for femoroacetabular impingement syndrome (FAIS) and to examine opioid requirements and occurrence of postoperative nausea and vomiting (PONV). METHODS: Between May 2022 and October 2022, patients (N = 68) undergoing arthroscopic surgery for FAIS were randomly allocated into 2 groups. The first group received an ultrasound-guided PENG preoperatively with 20 mL of 0.375% ropivacaine and standardized postoperative oral medication. The second group received a sham block preoperatively with 20 mL of 0.9% saline and standardized postoperative oral medication. The primary end point was pain scores (visual analog score [VAS], 0-10) during the first 24 hours postoperatively. To quantify clinical significance of outcome achievement for the VAS pain score, the minimal clinically important difference (MCID) was calculated using the half standard deviation method. The incidence of PONV as well as opioid usage (converted to morphine equivalent) within the first 24 hours were secondary outcomes. RESULTS: Randomization and permission were successfully obtained from 68 participants. From the fifteenth postoperative hour, the PENG group reported significantly less postoperative pain than the control group (24th postoperative hour: VAS pain PENG group 1.3 ± 0.9 [0-3]; 95% confidence interval {CI} 0.4-1.2 vs the VAS pain control group 2.4 ± 1.6 [0-5]; 95% CI 1.4-4.7; P = .009). The VAS pain score threshold for achieving the MCID at 24 hours postoperative was defined as a decrease of 1.1. 27 patients (79%) in the PENG group and 22 patients (65%) in the control group were able to achieve MCID (P = .009). Opioid dosage and postoperative nausea did not differ significantly between groups (P = .987 and P = .655, respectively). Concomitant complications such as falls, hematomas, or weakened muscles did not occur in either group. CONCLUSIONS: According to this study, a PENG block minimally reduced pain after arthroscopic treatment for FAIS between the 18th and 24th postoperative hours. The PENG group achieved significantly more often the pain VAS MCID. However, there was no proof that the PENG group consumed fewer opioids than the control group. Overall, PONV was found at a low and comparable rate. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

Medial patellofemoral ligament reconstruction using nonresorbable sutures yields comparable outcomes to reconstruction with a pedicled quadriceps tendon autograft when performed in addition to bony risk factor correction.

PURPOSE: To evaluate the results for reconstruction of the medial patellofemoral ligament using synthetic nonresorbable sutures (S-MPFL-R) in comparison to MPFL-R using quadriceps tendon autograft (QT-MPFL-R) in patients undergoing simultaneous correction of anatomic risk factors for lateral patellar instability (LPI) at a minimum of 2 years of follow-up. METHODS: Between November 2018 and June 2019, 19 patients (male/female 8/11; mean age 26 ± 7 years) underwent S-MPFL-R (FiberTape®) in combination with the correction of predisposing risk factors for LPI. The control group of 38 patients (male/female 16/22, mean age 26 ± 6 years) who underwent QT-MPFL-R was matched 1:2 by sex, age, anatomic risk factors, and concomitant surgical correction of bony risk factors. The Banff Patella Instability Instrument 2.0 (BPII 2.0) and a numerical analog scale (NAS 0-10) for patellofemoral pain and subjective knee joint function were used to assess patients' reported quality of life before and after surgery. RESULTS: The BPII 2.0 score increased from 35.0 ± 21.7 points to 79.7 ± 13.3 points (p < 0.0001) in the S-MPRL-R group and from 44.3 ± 19.6 points to 80.9 ± 15 points (p < 0.0001) in the QT-MPFL-R group from preoperatively to postoperatively, respectively, without any significant difference between the groups. In the S-MPFL-R group and QT-MPFL-R group, 95% (18/19) and 92% (35/38) of patients, respectively, crossed the minimally clinically important difference reported for the BPII 2.0. NAS values for pain and subjective knee joint function improved significantly in both groups (p < 0.0001, p < 0.0001) without any significant difference between the groups at the final follow-up. CONCLUSIONS: This study demonstrates that nonresorbable sutures can serve as a viable option for MPFL-R, yielding comparable outcomes compared to quadriceps tendon autograft reconstruction when performed concomitantly with the correction of anatomic risk factors for LPI. This option reduces the need for autologous tendon harvesting or the use of allografts for MPFL-R. LEVEL OF EVIDENCE: Level III.

Reconstruction of the medial patellofemoral ligament with nonresorbable suture tape normalizes patellar maltracking independent of patella-side fixation technique.

PURPOSE: Patellar maltracking caused by a rupture of the medial patellofemoral ligament (MPFL) can be improved by MPFL reconstruction (MPFL-R) with a tendon graft. Nonresorbable suture tape (FiberTape®, FT) is possibly becoming an option to tendon grafts for MPFL-R. Patella-side fixation of FT can be performed with suture anchors or via soft-tissue fixation. The aim of this study was to investigate patellar tracking considering soft-tissue-based and anchor-based patella-side fixation techniques. METHODS: In eight fresh-frozen human knee joint specimens (m/f 4/4; age 75 ± 10 years), the MPFL was identified, and a rupture was placed near the femoral insertion site. In the study group (SG; 4 knees), soft-tissue fixation of the FT was performed at the medial patellar retinaculum; in the control group (CG; 4 knees), FT was fixed at the patella via suture anchors. For native MPFL (nMPFL), ruptured ("injured") MPFL (iMPFL) and reconstructed MPFL (FT-MPFL-SG, respectively, FT-MPFL-CG) cone beam CT scans were performed in 15°, 30°, and 45° of knee joint flexion. Patellar tracking was assessed using the radiological parameters patellar tilt (PT), congruence angle (CA) and posterior patellar edge-trochlear groove ratio (PTR). RESULTS: All recorded radiological parameters increased, respectively, decreased in the CG and SG from the nMPFL to the iMPFL state. After MPFL-R, all parameters normalized when compared to the intact state (nMPFL), regardless of patella-side fixation technique. All investigated parameters of patellotrochlear alignment were positively, respectively, negatively significantly (p < 0.05) correlated throughout all evaluated conditions (nMPFL, iMPFL, FT-MPFL-SG, FT-MPFL-CG). CONCLUSION: MPFL-R with a nonresorbable suture tape can normalize patellar maltracking in fresh-frozen human knee joint specimens in earlier degrees of knee joint flexion independent of patella-side fixation technique. The investigated parameters of patellotrochlear alignment correlate with each other.

Patients older than 55 years regain sporting and recreational activities after arthroscopic anterior cruciate ligament reconstruction.

PURPOSE: (1) To compare sporting and recreational activity levels before and at a minimum 6 year follow-up, and (2) to assess the clinical and functional outcomes after anterior cruciate ligament (ACL) reconstruction in patients older than 55 years. METHODS: A retrospective evaluation of prospectively collected data of 150 patients with a mean age of 64 ± 4.5 (57-74) years was evaluated 8.6 ± 1.4 (6-11) years after primary ACL reconstruction using hamstring autograft. All patients were assessed using the International Knee Documentation Committee scoring system (IKDC), Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner activity level, and visual analog scale (VAS) for pain. The level of recreational activities was assessed using a sport-specific questionnaire. All patients were categorized according to Isolated and Combined ACL injury groups. RESULTS: The data of 125 patients were analyzed at the last follow-up. While 25 patients were lost to follow-up, 117 of 125 patients were active before their injury in at least one sports discipline compared to 121 of 125 patients after ACL reconstruction. One hundred and two (82%) patients had returned to their recreational activities at the final follow-up. The mean IKDC subjective score increased from 49.5 ± 23.2 (11.5-100) to 76.2 ± 14.8 (33.3-100) (p < 0.0001). The mean KOOS sport increased significantly from 36 ± 36.2 (0-100) to 74.1 ± 25.5 (0-100) (p < 0.0001). The mean VAS score improved from 6.0 ± 2.6 (0-10) to 1.0 ± 1.4 (0-6) (p < 0.0001). There was no significant difference in the median Tegner activity level (preoperative 5 (2-8) vs. follow-up 5 (2-8) (n.s). There was no significant difference in the number of sports disciplines and duration when comparing pre-injury and mid-term follow-up activity after ACL reconstruction. High-impact activities experienced a significant decline, while a significant increase in participation in low-impact activities was recorded. CONCLUSION: The majority of patients with symptomatic instability regained their pre-injury recreational activity level with excellent clinical and functional outcomes after arthroscopic ACL reconstruction. Nevertheless, a change from high-to low-impact activities has been observed. LEVEL OF EVIDENCE: Level IV.

Soft-tissue fixation is not inferior to suture-anchor fixation in reconstruction of the medial patellofemoral ligament using a nonresorbable suture tape.

PURPOSE: Reconstruction of the medial patellofemoral ligament (MPFL-R) with nonresorbable suture tape (FiberTape®, FT) is becoming popular. Patella-side fixation of the FT can be performed with suture anchors or via soft-tissue fixation. The aim of this study was to investigate whether patella-side soft-tissue fixation can achieve equivalent primary stability compared to suture-anchor fixation. METHODS: In ten human, fresh-frozen knee joint specimens (m/f 6/4; age 74 ± 9 a), the MPFL was identified and dissected near the femoral insertion site. In five knee joints, the MPFL-R using FT was performed with soft-tissue fixation at the patella (study group; SG), and in five knee joints, the FT was fixed via suture anchors (control group, CG). All reconstructions were evaluated until load to failure of the patella-side fixation with a displacement rate of 200 mm/min. RESULTS: The mean maximum load to failure in the SG was 395.3 ± 57.9 N. All reconstructions failed by complete tearing off the medial patellar retinaculum from its medial patellar margin, but fixation of the FT remained stable. In the CG, the mean maximum load to failure was 239.4 ± 54.5 N and was significantly different compared to the SG (p = 0.04). All reconstructions failed via pullout of the suture anchors. Stiffness and elongation did not differ between the groups, and no failure of the FT was observed in any of the specimens. CONCLUSION: Primary stability of soft-tissue MPFL-R using FT was superior to suture-anchor fixation. Both fixation techniques provided sufficient primary stability, superior to previously reported native MPFL tensile strengths. MPFL-R with FT could be a possible alternative procedure for MPFL-R, eliminating potential complications due to autologous tendon graft harvesting.

Combined distal femoral osteotomy and tibial tuberosity distalization is effective in patients presenting with patellar instability and patellofemoral pain due to patella alta and femoral malalignment.

INTRODUCTION: Patellar malalignment has been considered one of the major pathomechanical causes of patellofemoral instability and pain. The results have been reported after femoral varization/torsional osteotomy and tibial tuberosity distalization osteotomy (TTD-O). However, the combination of a femoral deformity (genu valgum/increased femur antetorsion) and patella alta remains underreported. Therefore, the aim of this study was to investigate the clinical outcomes of patients simultaneously treated by distal femoral osteotomy and TTD-O. The hypothesis was that restoration of patellofemoral (PF) alignment via the abovementioned osteotomies would achieve good patient-reported outcome measures. MATERIALS AND METHODS: Between 2016 and 2019, a series of 25 knees in 20 patients were treated by a distal femoral osteotomy combined with a TTD-O aiming to correct patellofemoral malalignment consisting of genu valgum and/or increased femur antetorsion and patella alta. Six patients were lost to follow-up, and one patient refused to participate. Thus, 17 knees in 13 patients (male/female 1/12; age 27.4 ± 5.4 years) were included and comprised the study group for this investigation. Patients were evaluated after a mean of 3.1 ± 0.9 years postoperatively. The Kujala anterior knee pain scale and the PF-subscale of the Knee Osteoarthritis and Outcome score (KOOS-PF) were used to assess patients' reported outcome measures from pre- to postoperatively. RESULTS: The mean amount of torsional correction, valgus correction, and tibial tuberosity distalization averaged 14° (10°-18°), 5.2° (3.8°-8°), and 9 mm (6°-15 mm), respectively. The Kujala score increased by an average of 24.18 points from a mean of 66.6 ± 18.3 points (34-93 points) preoperatively to 90.8 ± 14.2 points (44-100 points) postoperatively (95% CI - 33.0 to - 15.3; p < 0.0001). The KOOS-PF score increased by an average of 33.7 points from a mean of 49.5 ± 24.5 points (9.1-88.6 points) preoperatively to 83.2 ± 21.6 points (15.9 -100 points) postoperatively (95% CI - 47.5 to - 19.9; p < 0.0001). CONCLUSION: The findings of this study indicate that the combination of a distal femoral osteotomy and a tibial tuberosity distalization osteotomy is effective in patients presenting with patellar instability and patellofemoral pain due to patella alta and femoral malalignment.

Revision lateralization osteotomy of the tibial tubercle has excellent outcomes in patients suffering from previous medial tibial tubercle overcorrection.

INTRODUCTION: Tibial tubercle osteotomy (TTO) is a common procedure used to treat patients with patellofemoral instability (PFI) and osteoarthritis (PFOA). Medial patellar maltracking due to previous excessive medialization of the tibial tubercle has rarely been reported. Therefore, the goal of this study was to assess patient-reported outcome measures (PROMs) after revision osteotomy with lateralization of the tibial tubercle (RL-TTO) to correct medial patellofemoral maltracking. MATERIALS AND METHODS: Between 2017 and 2021, a series of 11 patients (male/female 1/10; age 35.8 ± 10.5 years) were treated by RL-TTO, of whom 8 patients could be retrospectively evaluated after a mean of 32.4 ± 15.1 months (range 18-61 months) postoperatively. The Kujala anterior knee pain scale, the patellofemoral subscale of the Knee Osteoarthritis and Outcome Score (KOOS-PF), and a numeric analog scale (NAS; 0-10) regarding anterior knee pain (AKP) at rest and during activity were assessed from pre- to postoperatively. RESULTS: The preoperative mean tibial tubercle-trochlear groove (TT-TG) and tibial tubercle-posterior cruciate ligament (TT-PCL) distances were - 6.5 ± 6.5 mm and 0.7 ± 4.6 mm, respectively. The intraoperatively determined amount of tibial tubercle lateralization averaged 10.7 ± 3.6 mm. The Kujala score and KOOS-PF improved significantly from 33.6 ± 10.1 (23-51) points to 94.4 ± 6.2 points (82-100) (p < 0.001) and from 20.6 ± 13.2 points (0-43.3) to 87.3 ± 9.9 points (72.8-100) (p < 0.001) from pre- to postoperatively, respectively. Pain at rest decreased from 5.8 ± 1.9 to 0.8 ± 0.9 (p < 0.001), and pain during activity decreased from 8.6 ± 1.3 to 1.6 ± 1.5 (p < 0.001). CONCLUSION: RL-TTO significantly improved subjective knee function and AKP in patients suffering from medial patellar maltracking due to previous excessive tibial tubercle medialization osteotomy at short-term follow-up.

The J-sign and the body mass index determine the disease-specific quality of life in patients with lateral patellar instability.

PURPOSE: To determine which risk factors for patellar instability contribute most relevantly to patients' subjective disease-specific quality of life, aiming to provide implications on the overall treatment decision-making process. METHODS: A total of 182 consecutive patients (male/female 70/112; mean age 23.6 ± 7.3 years) with a history of patellar instability were prospectively enrolled in this study. Patient age, body mass index (BMI), number of dislocations, reversed dynamic patellar apprehension test (ReDPAT), J-sign severity, and pathoanatomic risk factors of patellar instability were assessed. The statistical analysis evaluated the relationships among those variables and determined their ability to predict the Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) as a disease-specific quality of life measure. Using Spearman correlation, ANOVA and Fisher's exact test, all variables with ANOVA p ≤ 0.1 or Spearman's abs (rho) > 0.1 were entered into a multivariate linear model using backward-stepwise selection. RESULTS: Analysis of the individual variables' ability to predict BPII 2.0 score values revealed 'age', 'BMI', 'ReDPAT', 'high grade of trochlear dysplasia', and 'high-grade J-Sign' as possible relevant factors. Backward-stepwise multivariate regression analysis yielded a final parsimonious model that included the factors 'BMI' and 'J-Sign (Grade II and III)' as the most relevant parameters influencing BPII 2.0 score values (adjusted R2 = 0.418; p < 0.001), with a cutoff value for BMI found at 28 kg/m2 (p = 0.01). CONCLUSION: The results of this study indicate that in patients with lateral patellar instability, a high-grade J-sign and an increased BMI significantly impact subjective disease-specific quality of life. LEVEL OF EVIDENCE: Level IV.

Revision surgery for failed medial patellofemoral ligament reconstruction results in better disease-specific outcome scores when performed for recurrent instability than for patellofemoral pain or limited range of motion.

PURPOSE: Medial patellofemoral ligament reconstruction (MPFL-R) is an important treatment for recurrent patellar instability. Although complications such as redislocation, patellofemoral pain (PFP) and restricted knee range of motion have been reported, few studies have investigated the results of revision surgery for failed MPFL-R. Thus, the aim of this study was to determine the results of the tailored revision surgery after considering the cause of the reconstruction failure. MATERIALS AND METHODS: Between 2015 and 2019, 28 patients (male/female 9/19; age 26.2 ± 6.4 years) underwent revision surgery for failed MPFL-R. The patients were grouped into the "recurrent instability" (SG1) group and "PFP" and/or "restricted range of motion" (SG2) group. Preoperatively, the clinical data, anatomical risk factor profile, and position of the femoral MPFL tunnel were determined for each patient. The Banff Patella Instability Instrument 2.0 (BPII 2.0) and numerical analogue scale (NAS 0-10) were administered preoperatively and at the final follow-up for the subjective assessment of the PFP and knee joint function. RESULTS: Overall, the BPII 2.0 score improved from 28.8 ± 16.6 points preoperatively to 68.0 ± 22.7 points (p < 0.0001) postoperatively. SG1 exhibited an increase in the BPII 2.0 score from 28.9 ± 20.2 points to 75.7 ± 23 points (p < 0.0001). PFP decreased from 6.8 ± 2.4 to 1.6 ± 1.9 (p < 0.0001), while the knee joint function increased from 4.3 ± 2.5 to 8.8 ± 1.6 (p < 0.0001). In SG2, the BPII 2.0 score increased from 28.7 ± 12.6 points preoperatively to 57.7 ± 19.7 points (p = 0.0002) postoperatively and was thus significantly lower than that in SG1 (p = 0.038). The intensity of PFP decreased from 6.6 ± 3.0 preoperatively to 2.1 ± 1.9 postoperatively (p = 0.0006), while the subjective knee joint function improved from 3.2 ± 1.4 preoperatively to 7.6 ± 2.3 postoperatively (p < 0.0001). The differences between the groups were not significant. CONCLUSION: Tailored revision surgery for failed MPFL-R significantly improves the patient-reported disease-specific quality of life. The study results indicate that patients undergoing revision surgery as a consequence of patellar redislocation appear to benefit more from revision surgery than those patients undergoing revision due to postoperative PFP and/or a limited knee joint range of motion. LEVEL OF EVIDENCE: Level IV.

Treatment of acquired patella baja by proximalization tibial tubercle osteotomy significantly improved knee joint function but overall patient-reported outcome measures remain diminished after two to four years of follow-up.

INTRODUCTION: Acquired patella baja is often characterized by painful limitation of knee joint range of motion and anterior knee pain (AKP). Only few studies have evaluated the effectiveness of surgical treatment in terms of patient-reported outcome measures (PROM's) and sports activity. Thus, the goal of this study was to assess PROM's and sports activity after proximalization tibial tubercle osteotomy (P-TTO) in patients with symptomatic patella baja. METHODS: Between 2016 and 2018, a case series of 11 patients (male/female 4/7; age 48 ± 12 years) were treated by P-TTO and were retrospectively evaluated after a mean of 33.7 months (range 24-51 months). The Tegner activity score and the Kujala anterior knee pain scale were used in addition to a visual analogue scale (VAS; 0-10) regarding self-reported knee joint function and intensity of AKP. Radiographic assessment included the measure of patellar height using the Caton-Deschamps (CD) and Blackburne-Peel (BP) index. RESULTS: Postoperatively both the CD and the BP index increased to normality (p < 0.0001; p = 0.0012). Knee joint flexion improved from 100 ± 32° preoperatively to 123 ± 14° postoperatively (p = 0.0235). AKP decreased from 6.5 ± 2.1 points preoperatively to 3.7 ± 2.1 points postoperatively (p = 0.0061). This was accompanied by a significant increase in self-reported knee joint function from 1.8 ± 1.2 points preoperatively to 6.8 ± 2.3 points postoperatively (p = 0.0001) and an increase of the Tegner activity score from 1.8 ± 1.6 points preoperatively to 3.9 ± 1.5 points postoperatively (p = 0.0074). Although the Kujala score improved significantly by an average of 31.55 points (p = 0.001) overall score results remained reduced at 65.6 ± 17.9 points at final follow-up. CONCLUSION: P-TTO yielded significant improvements in terms of AKP, subjective knee joint function and sports activity. However, the overall Kujala score results remained reduced, indicating that surgical correction of patellar height is not sufficient to relieve all patients' complaints. In addition, the incidence of postoperative complications was high.

The reversed dynamic patellar apprehension test mimics anatomical complexity in lateral patellar instability.

PURPOSE: To develop a dynamic physical examination test that functionally simulates actual patellar instability events and that mimics the range of patellar stabilizer insufficiency in an individual patient. METHODS: Seventy-eight consecutive patients (male/female 35/43; mean age 22 ± 7 years) with recurrent lateral patellar instability and 35 controls (male/female 16/19; mean age 31 ± 14 years) were prospectively evaluated using the reversed dynamic patellar apprehension test (ReDPAT). Anatomical predisposition was assessed according to Dejour's classification of trochlear dysplasia, tibial tuberosity-trochlear groove distance, tibial tuberosity-posterior cruciate ligament distance, patellar height, and varus/valgus malalignment. RESULTS: The study group had an average of 3.4 ± 1.0 (1-6) anatomical risk factors for lateral patellar dislocation. Severe trochlear dysplasia (84%) and patella alta (49%) were the most common. Test sensitivity and specificity was 93.7% (95% CI 0.8584-0.9791) and 88.2% (95% CI 0.7255-0.9670), respectively. The positive predictive value reached 94.9% (95% CI 0.8739-0.9859) and the negative predictive value was 85.7% (95% CI 0.6974-0.9519). The ReDPAT results became positive at a mean knee flexion angle of 58° ± 17° (20°-90°). Knee flexion angle correlated significantly with the severity of trochlear dysplasia (p = 0.018), valgus deformity (p = 0.011), and the total number of anatomical risk factors (p = 0.02). CONCLUSION: This study introduced the reversed dynamic patellar apprehension test as a reliable clinical examination tool in the assessment of lateral patellar instability. The results of this study indicate that the degree of knee joint flexion at which the provocative sense of apprehension becomes positive correlates with severity of trochlear dysplasia, valgus deformity and the total number of anatomical risk factors for patellar instability. This test indicates the patient-specific end of stable patellar tracking and the beginning of patellar stabilizer insufficiency. Therefore, this test might be helpful in deciding for or against a bony procedure in the treatment of patellar dislocation. LEVEL OF EVIDENCE: II.

Successful adaption of the Banff Patella Instability Instrument (BPII) 2.0 into German.

PURPOSE: The aim of this study was to adapt, translate, and validate the Banff Patella Instability Instrument (BPII) 2.0 into German, enabling its use by German-speaking professionals for the evaluation of patients who present with patellofemoral instability. METHODS: Forward and backward translation was performed according to international recommendations. The final German version of the BPII 2.0 was investigated in patients with confirmed diagnoses of recurrent patellofemoral instability in Germany, Austria, and Switzerland. All patients received two packages of questionnaires, each containing the BPII 2.0, Kujala scoring questionnaire, Norwich Patella Instability scoring questionnaire, Short Form-36 (SF-36), and a visual analogue scale (VAS)-scale for pain and disability. The first and second packages of questionnaires were to be completed 7 days apart. The following parameters were assessed: internal consistency, test-retest reliability, floor and ceiling effects, and construct validity. RESULTS: The study population consisted of 64 patients (24 males and 40 females). The average age of the patients was 22 ± 6 years. The internal consistency (Cronbach's alpha) was excellent at both time points (0.93 and 0.95), and the test-retest reliability (ICC) was good (0.89). There were no floor or ceiling effects. There were statistically significant correlations between the BPII 2.0 and all other outcome measures apart from SF-36 mental health. CONCLUSION: The BPII 2.0 was successfully adapted into German. It is a reliable and valid instrument for evaluation of German-speaking patients who present with patellofemoral instability. LEVEL OF EVIDENCE: III.

The use of tibial tuberosity-trochlear groove indices based on joint size in lower limb evaluation.

PURPOSE: The correlation between tibial tuberosity-trochlear groove distance (TT-TG) and joint size, taking into account several different parameters of knee joint size as well as lower limb dimensions, is evaluated in order to assess whether TT-TG indices should be used in instead of absolute TT-TG values. METHODS: This study comprised a retrospective analysis of knee CT scans, including 36 cases with patellofemoral instability (PFI) and 30 controls. Besides TT-TG, five measures of knee joint size were evaluated in axial CT slices: medio-lateral femur width, antero-posterior lateral condylar height, medio-lateral width of the tibia, width of the patella and the proximal-distal joint size (TT-TE). Furthermore, the length of the femur, the tibia and the total leg length were measured in the CT scanogram. Correlation analysis of TT-TG and the other parameters was done by calculating the Spearman correlation coefficient. RESULTS: In the PFI group lateral condylar height (r = 0.370), tibia width (r = 0.406) and patella width (r = 0.366) showed significant moderate correlations (p < 0.03) with TT-TG. Furthermore, we found a significant correlation between TT-TG and tibia length (r = 0.371) and total leg length (r = 381). The control group showed no significant correlation between TT-TG and knee joint size or between TT-TG and measures of lower limb length. CONCLUSIONS: Tibial tuberosity-trochlear groove distance correlates with several parameters of knee joint size and leg length in patients with patellofemoral instability. Application of indices determining TT-TG as a ratio of joint size could be helpful in establishing the indication for medial transfer of the tibial tuberosity in patients with PFI. LEVEL OF EVIDENCE: Level III.

Sagittal magnetic resonance imaging-scan orientation significantly influences accuracy of femoral posterior condylar offset measurement.

BACKGROUND: In total knee arthroplasty the femoral posterior condylar offset (PCO) may serve as a potential branch for correct femoral component positioning. The technique of adjusting the sagittal magnetic resonance imaging (MRI)-scan on which it is measured has not been investigated in previous literature, but may be subject to variances due to knee joint positioning or axial localizer scan angulation. The purpose of this study was to investigate the effect of simulated femur rotation on the accuracy of PCO measurement. MATERIALS AND METHODS: Ten asymptomatic knee joints underwent MRI investigations. A sagittal plane perpendicular to the transepicondylar axis was defined as the true-sagittal plane (tsP). Sagittal images were reformatted in the tsP and angulated by 5° and - 5° in medial and lateral direction. In total each knee received three scans in 0°, 5° and - 5° axial localizer scan angulation. Medial and lateral PCO measurement was performed in each MRI-scan angulation. RESULTS: Simulated external rotation decreased medial PCO size by 1.7 mm (95% CI 0.5994-3.127) (p = 0.012), and simulated internal rotation increased medial PCO size by 2.1 mm (95% CI 1.142-2.994) (p = 0.001). Lateral PCO size increased by 1.9 mm (95% CI 0.5660-3.412) and decreased by 2.1 mm (95% CI 1.142-2.994) with simulated external and internal rotation, respectively (p = 0.011; p = 0.0007). CONCLUSION: This study shows the high sensitivity of medial and lateral PCO measurements to small changes of MRI axial localizer scan angulations simulating minor degrees of internal or external femur rotation. Thus, absolute PCO values should be interpreted with caution if the sagittal image acquisition is not standardized.

IL-1ß-Induced Accumulation of Amyloid: Macroautophagy in Skeletal Muscle Depends on ERK.

The pathology of inclusion body myositis (IBM) involves an inflammatory response and ß-amyloid deposits in muscle fibres. It is believed that MAP kinases such as the ERK signalling pathway mediate the inflammatory signalling in cells. Further, there is evidence that autophagic activity plays a crucial role in the pathogenesis of IBM. Using a well established in vitro model of IBM, the autophagic pathway, MAP kinases, and accumulation of ß-amyloid were examined. We demonstrate that stimulation of muscle cells with IL-1ß and IFN-γ led to an increased phosphorylation of ERK. The ERK inhibitor PD98059 diminished the expression of proinflammatory markers as well as the accumulation of ß-amyloid. In addition, IL-1ß and IFN-γ led to an increase of autophagic activity, upregulation of APP, and subsequent accumulation of ß-sheet aggregates. Taken together, the data demonstrate that the ERK pathway contributes to formation of ß-amyloid and regulation of autophagic activity in muscle cells exposed to proinflammatory cell stress. This suggests that ERK serves as an important mediator between inflammatory mechanisms and protein deposition in skeletal muscle and is a crucial element of the pathology of IBM.

Results of medial patellofemoral ligament reconstruction compared with trochleoplasty plus individual extensor apparatus balancing in patellar instability caused by severe trochlear dysplasia: a systematic review and meta-analysis.

PURPOSE: Many studies have reported satisfactory clinical outcomes and low redislocation rates after reconstruction of the medial patellofemoral ligament (MPFL) for the treatment of lateral patellar instability. Despite uncorrected severe trochlear dysplasia (Dejour type B to D) being acknowledged as a major reason for less favourable clinical outcomes and a higher incidence of patellar redislocations after an isolated MPFL reconstruction, the evidence for a deepening trochleoplasty procedure remains scarce in the current literature. The hypothesis of this systematic review and meta-analysis was that a deepening trochleoplasty in combination with an a la carte extensor apparatus balancing procedure provides lower redislocation rates and superior clinical outcomes than isolated MPFL reconstruction in patients with lateral patellar instability caused by severe trochlear dysplasia. METHODS: A systematic review of the literature was conducted using specific inclusion and exclusion criteria for clinical studies reporting index operations (trochleoplasty and MPFL reconstruction) for the treatment of patellar instability caused by severe trochlear dysplasia. The Kujala score was analysed as the primary clinical outcome parameter in a random effects meta-analysis. RESULTS: Ten uncontrolled studies with a total of 407 knees (374 patients) were included in this analysis. The MPFL group comprised 4 studies with a total of 221 knees (210 patients), and the trochleoplasty group comprised 6 studies with a total of 186 knees (164 patients). The mean preoperative Kujala score ranged between 50.4 and 70.5 in the MPFL group and between 44.8 and 75.1 in the trochleoplasty group. The pooled Kujala score increased significantly by 26.4 (95% CI 21.4, 31.3; P < 0.00001) points in the MPFL group and by 26.2 (95% CI 19.8, 32.7; P < 0.00001) points in the trochleoplasty group. The post-operative patellar redislocation/subluxation rate was 7% in the MPFL group and 2.1% in the trochleoplasty group. CONCLUSION: This analysis found significant post-operative improvements in patient-reported outcomes for patients undergoing both an MPFL reconstruction and in those undergoing a trochleoplasty plus an individual extensor apparatus balancing procedure when assessed using the Kujala score. The likelihood of preventing the patella from subsequent post-operative redislocation/subluxation was, however, greater in patients who underwent trochleoplasty plus extensor balancing. LEVEL OF EVIDENCE: IV.

Novel single-loop and double-loop knot stitch in comparison with the modified Mason-Allen stitch for rotator cuff repair.

PURPOSE: In rotator cuff repair, strong and long-lasting suturing techniques that do not require additional implants are needed. This study examines the ultimate load to failure and the Young's modulus at the suture-tendon interface for a novel single-loop knot stitch and double-loop knot stitch. These values are compared to those of the modified Mason-Allen stitch. METHODS: Twenty-four infraspinatus muscles with tendons were dissected from porcine shoulders (twelve Goettingen minipigs). The preparations were randomly allocated to three groups of eight samples. Load-to-failure testing of the single-loop knot stitch, the double-loop knot stitch and the mMAS were performed using a Zwick 1446 universal testing machine (Zwick-Roell AG, Ulm, Germany). RESULTS: The highest ultimate load to failure for the three techniques occurred with the double-loop knot stitch with a median value of 382.2 N (range 291.8-454.2 N). These values were significantly higher than those of the single-loop knot stitch, which had a median value of 259.5 N (range 139.6-366.3 N) and the modified Mason-Allen stitch, which had a median value of 309.3 N (range 84.55-382.9 N). The values of the single-loop knot stitch and the modified Mason-Allen stitch did not differ significantly. Regarding the Young's modulus, no significant differences were found between the double-loop knot stitch with a median value of 496.02 N/mm² (range 400.4-572.6 N/mm²) and the modified Mason-Allen stitch with 498.5 N/mm² (range 375.5-749.2 N/mm²) with respect to the stiffness of the suture-tendon complex. The median value for the Young's modulus of the single-loop knot stitch of 392.1 N/mm² (range 285.7-510.6 N/mm²) was significantly lower than those of the double-loop knot stitch and modified Mason-Allen stitch. CONCLUSION: This in vitro animal study demonstrated that both the single-loop knot stitch and the double-loop knot stitch have excellent ultimate load-to-failure properties when used for rotator cuff repair. The introduced single-loop knot stitch and double-loop knot stitch offer an alternative to other common used stitch techniques in rotator cuff repair.

Characteristics of femorotibial joint geometry in the trochlear dysplastic femur.

The medial and lateral tibia plateau geometry has been linked with the severity of trochlear dysplasia. The aim of the present study was to evaluate the tibial slope and the femoral posterior condylar offset in a cohort of consecutive subjects with a trochlear dysplastic femur to investigate whether the condylar offset correlates with, and thus potentially compensates for, tibial slope asymmetry. Magnetic resonance imaging was used to assess the severity of trochlear dysplasia as well as the tibial slope and posterior offset of the femoral condyles separately for the medial and lateral compartment of the knee joint in 98 subjects with a trochlear dysplastic femur and 88 control subjects. A significant positive correlation was found for the medial tibial slope and the medial posterior condylar offset in the study group (r(2) = 0.1566; P < 0.001). This relationship was significant for all subtypes of trochlear dysplasia and was most pronounced in the severe trochlear dysplastic femur (Dejour type D) (r(2) = 0.3734; P = 0.04). No correlation was found for the lateral condylar offset and the lateral tibial slope in the study group or for the condylar offset and the tibial slope on both sides in the control group. The positive correlation between the medial femoral condylar offset and the medial tibial slope, that is, a greater degree of the medial tibial slope indicated a larger offset of the medial femoral condyle, appears to represent a general anthropomorphic characteristic of distal femur geometry in patients with a trochlear dysplastic femur.

Which patellae are likely to redislocate?

PURPOSE: The purpose of this study was to identify the risk factors for recurrent lateral patellar dislocations and to incorporate those factors into a patellar instability severity score. METHODS: Sixty-one patients [male/female 35/26; median age 19 years (range 9-51 years)] formed the study group for this investigation. Within the study group, 40 patients experienced a patellar redislocation within 24 months after the primary dislocation, whereas 21 patients, who were assessed after a median follow-up of 37 months (range 24-60 months), had not experienced a subsequent episode of lateral patellar instability. In all patients, age at the time of the primary dislocation, gender, the affected body side, body mass index, bilateral instability, physical activity according to Baecke's questionnaire, the grade of trochlear dysplasia, patellar height, tibial tuberosity-trochlear groove (TT-TG) distance, and patellar tilt were assessed. The odds ratio (OR) of each factor with regard to the patellar redislocation was calculated using contingency tables. Based on these data, a "patellar instability severity score" was calculated. RESULTS: The patellar instability severity score has six factors: age, bilateral instability, the severity of trochlear dysplasia, patella alta, TT-TG distance, and patellar tilt; the total possible score is seven. Reapplying this score to the study population revealed a median score of 4 points (range 2-7) for those patients with an early episode of patellar redislocation and a median score of 3 points (range 1-6) for those without a redislocation (p=0.0004). The OR for recurrent dislocations was 4.88 (95% CI 1.57-15.17) for the patients who scored 4 or more points when compared with the patients who scored 3 or fewer points (p=0.0064). CONCLUSION: Based on the individual patient data, the patellar instability severity score allows an initial risk assessment for experiencing a recurrent patellar dislocation and might help differentiate between responders and non-responders to conservative treatment after primary lateral patellar instability. LEVEL OF EVIDENCE: Case-control study, Level III.

Influence of tibial slope asymmetry on femoral rotation in patients with lateral patellar instability.

PURPOSE: The geometry of the tibial plateau and its influence on the biomechanics of the tibiofemoral joint has gained increased significance. However, no quantitative data are available regarding the inclination of the medial and lateral tibial slope in patients with patellar instability. It was therefore the purpose of this study to evaluate tibial slope characteristics in patients with patellar dislocations and to assess the biomechanical effect of medial-to-lateral tibial slope asymmetry on lateral patellar instability. METHODS: Medial and lateral tibial slope was measured on knee magnetic resonance images in 107 patients and in 83 controls. The medial-to-lateral tibial slope asymmetry was assessed as the intra-individual difference between the medial and lateral tibial plateau inclination considering severity of trochlear dysplasia. The effect of tibial slope asymmetry on femoral rotation was calculated by means of radian measure. RESULTS: Severity of trochlear dysplasia was significantly associated with an asymmetric inclination of the tibial plateau. Whereas the medial tibial slope showed identical values between controls and study patients (n.s.), lateral tibial plateau inclination becomes flatter with increasing severity of trochlear dysplasia (p < 0.01). Consequently, the intra-individual tibial slope asymmetry increased steadily (p < 0.01) and increased internal femoral rotation in 20° and 90° of knee flexion angles in patients with severe trochlear dysplasia (p < 0.01). In addition, the extreme values of internal femoral rotation were more pronounced in patients with patellar instability, whereas the extreme values of external femoral rotation were more pronounced in control subjects (p = 0.024). CONCLUSION: Data of this study indicate an association between tibial plateau configuration and internal femoral rotation in patients with lateral patellar instability and underlying trochlear dysplasia. Thereby, medial-to-lateral tibial slope asymmetry increased internal femoral rotation during knee flexion and therefore might aggravate the effect of femoral antetorsion in patients with patellar instability. LEVEL OF EVIDENCE: III.