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Background: The gluteus minimus (GMin) and gluteus medius (GMed) are important dynamic stabilizers of the hip, but quantitative data on their biomechanical roles in stabilizing the hip are currently lacking. Purpose: To (1) establish a reproducible biomechanical cadaveric model of the hip abductor complex and (2) characterize the effects of loading the GMin and GMed on extraneous femoral rotation and distraction. Study Design: Controlled laboratory study. Methods: A total of 10 hemipelvises were tested in 4 muscle loading states: (1) unloaded, (2) the GMin loaded, (3) the GMed loaded, and (4) both the GMin and GMed loaded. Muscle loads were applied via cables, pulleys, and weights attached to the tendons to replicate the anatomic lines of action. Specimens were tested under internal rotation; external rotation; and axial traction forces at 0°, 15°, 30°, 60°, and 90° of hip flexion. Results: When loaded together, the GMin and GMed reduced internal rotation motion at all hip flexion angles (P < .05) except 60° and reduced external rotation motion at all hip flexion angles (P < .05) except 0°. Likewise, when both the GMin and GMed were loaded, femoral distraction was decreased at all angles of hip flexion (P < .05). Conclusion: The results of this study demonstrated that the GMin and GMed provide stability against rotational torques and distractive forces and that the amount of contribution depends on the degree of hip flexion. Clinical Relevance: Improved understanding of the roles of the GMin and GMed in preventing rotational and distractive instability of the hip will better guide treatment of hip pathologies and optimize nonoperative and operative therapies.

Purpose Although long-term reports of total hip arthroplasty (THA) showed successful results, instability remains a major complication. Recently, dual-mobility cups (DMC) have gained more and more interest among clinicians, with encouraging results in terms of lower rate of dislocation associated with good clinical results, but a lack of evidence exists regarding the real efficacy of this implant design compared to traditional fixed-bearing total hip arthroplasties. Methods A systematic search was performed in PubMed, Google scholar, Cochrane Library, and EMBASE by two independent reviewers for comparative studies available till December 2017, with the primary objective to demonstrate a real lower dislocation rate of DMC implants compared to unipolar fixed-bearing cup designs. A meta-analysis was conducted with the collected pooled data about dislocation rate, calculating the risk difference (RD) and relative risk (RR) with 95% CI for dichotomous variables. Heterogeneity was tested using the χ 2 and Higgins’ I 2 tests. A fixed-effect model was used because the statistical heterogeneity was below 50%. Results After performing a critical exclusion process, the number of eligible studies included for final synthesis considered was 15, describing the results of a total of 2408 total hip arthroplasties (50.6% with a dual-mobility acetabular cup design, 49.4% with a standard fixed-bearing design). The fixed-effect meta-analysis showed a slight significant risk ratio of 0.16 (95% CI, 0.09, 0.28; I 2  = 0%, p  < 0.00001); a statistically significant difference in favor of the DMC group was maintained also considering only primary or revision arthroplasties, traumatic fractures or elective patients with diagnosis of osteoarthritis, avascular osteonecrosis or rheumatic arthritis. Conclusions With the intrinsic limitations of our study design and based on the current available data, this study demonstrates that dual-mobility acetabular components decrease the risk of post-operative instability also in high-risk patients, both in primary and revision hip arthroplasties. However, new high-quality studies, possibly with a randomized control design, should be undertaken in order to strengthen the present data. Study design Level of Evidence III, therapeutic study.

Purpose Surgical reconstruction is the current standard for ACL rupture treatment in active individuals. Recently, there is renewed interest in primary repair of proximal ACL tears. Despite this, ACL biology and healing potential are currently not well understood. Vascularity is paramount in ACL healing; however, previous ACL vascularity studies have been limited to qualitative histological and dissection-based techniques. The study objective was to use contrast-enhanced quantitative-MRI to compare relative perfusion of proximal, middle, and distal thirds of the in situ ACL. We hypothesized perfusion would be greatest in the proximal third. Methods Fourteen cadaveric knees were studied (8 females, 6 males), age 25–61 years. Superficial femoral, anterior tibial, and posterior tibial arteries were cannulated; without intraarticular dissection. Contrast-enhanced quantitative-MRI was performed using a previously established protocol. ACL regions corresponding to proximal, middle, and distal thirds were identified on sagittal-oblique pre-contrast images. Signal enhancement (normalized to tibial plateau cartilage) was quantified to represent regional perfusion as a percentage of total ACL perfusion. Comparative statistics were computed using repeated measures ANOVA, and pairwise comparisons performed using the Bonferroni method. Results Relative perfusion to proximal, middle, and distal ACL zones were 56.0% ±17.4%, 28.2% ±14.6%, and 15.8% ±16.3%, respectively ( p  = 0.002). Relative perfusion to the proximal third was significantly greater than middle ( p  = 0.007) and distal ( p  = 0.001). No statistically relevant difference in relative perfusion was found to middle and distal thirds ( p  = 0.281). Post-hoc subgroup analysis demonstrated greater proximal perfusion in males (66.9% ± 17.3%) than females (47.8% ± 13.0%), p  = 0.036. Conclusion Using quantitative-MRI, in situ adult ACL demonstrated greatest relative perfusion to the proximal third, nearly 2 times greater than the middle third and 3 times greater than the distal third. Knowledge of differential ACL vascular supply is important for understanding pathogenesis of ACL injury and the process of biological healing following various forms of surgical treatment.

Background: A serious concern with surgical procedures around the hip joint is iatrogenic injury of the arterial supply to the femoral head (FH) and consequent development of FH osteonecrosis. Cam-type morphology can extend to the posterosuperior area. Understanding the limit of the posterior superior extension of the femoral osteochondroplasty is paramount to avoid underresection and residual impingement while maintaining FH vascularity. Purpose/Hypothesis: The aim of this study was to quantify the impact of arthroscopic femoral osteochondroplasty on the FH vascular supply. It was hypothesized that keeping the superior extension of the resection zone anterior to the 12-o’clock position would maintain FH vascularity. Study Design: Case series; Level of evidence, 4. Methods: Ten adult patients undergoing arthroscopic femoroacetabular impingement (FAI) surgery were included in the study. Computed tomography (CT) scans were obtained before and after arthroscopic osteochondroplasty to define the extension of resection margins. To quantify FH vascularity, postoperative dynamic contrast–enhanced magnetic resonance imaging (DCE-MRI) was obtained at 2 time points: immediately after surgery and at the 3-month follow-up. Custom MRI analysis software was used to quantify perfusion. Results: CT scan analysis demonstrated that the superior resection margin was maintained anterior to the 12-o’clock position in half of the patients. The remining 5 patients had a mean posterior extension of 11.4° ± 7.5°. The immediate postoperative DCE-MRI revealed diminished venous outflow in the operative side but no difference in overall FH perfusion. At the 3-month follow-up DCE-MRI, there was no perfusion difference between the operative and nonoperative FHs. Conclusion: This study provides previously unreported quantitative MRI data on in vivo perfusion of the FH after the commonly performed arthroscopic femoral osteochondroplasty for the treatment of cam-type FAI. Maintaining resection margins anterior to the 12-o’clock position, or even 10° posteriorly, was not observed to impair perfusion to the FH.

Abstract Purpose While predominant blood supply to the adult patella enters inferomedially, little is known about skeletally immature patellar perfusion. Improved knowledge of immature patella vascularity can further understanding of osteochondritis dissecans, dorsal defects of the patella and bipartite patella, and help ensure safe surgical approaches. We hypothesized that the immature patella would exhibit more uniform blood flow. The study purpose was to quantify immature patella regional perfusion in comparison with adults. Methods Ten cadaveric knees were utilized (five immature, five mature). The superficial femoral artery was cannulated proximally. Signal enhancement increases were compared from pre- to post-contrast MRI to assess relative arterial contributions to patella regions (quadrants, anterior/posterior, superior/inferior, medial/lateral, and outer/inner). Results Quantitative-MRI analysis revealed similar distribution of enhancement between the immature and mature patella. The inferior pole exhibited significantly higher arterial contribution versus superior pole in both immature and mature groups (p = 0.009; both groups), while the inferomedial quadrant had the highest arterial contribution of all quadrants in both groups. The superolateral quadrant demonstrated the lowest arterial contribution in the immature group and second lowest in the adult group. The patella outer periphery had significantly greater arterial contribution than the inner central region in both immature (p = 0.009) and mature (p = 0.009) groups. Conclusion Distribution of arterial contributions between the immature and mature patella was similar. Our results highlight the importance of inferior and inferomedial blood supply in both immature and mature patellas. These findings have implications for paediatric and adult patients; surgical damage to inferior patellar vessels should be avoided to prevent associated complications.

Objectives: Braces are commonly used in Orthopaedic to protect repaired tissue from excessive stress that can compromise the healing process. Some of these braces can become a nuisance, especially the ones commonly used following proximal hamstring repairs. The idea is to limit hip flexion and knee extension to avoid stretching of the hamstrings. However, this immobilization creates discomfort and limitation during the basic daily needs, possibly compromising patient satisfaction. We hypothesis that proximal hamstring repairs can be safely managed, without brace immobilization and allowing partial weight bearing immediately after surgery, and result in excellent outcomes with minimal complications. Methods: We identify 57 patients that underwent surgical repair of proximal hamstring injuries. The repairs were fixed using suture anchors, and the same surgical technique were performed by a single sport medicine fellowship trained Orthopaedic surgeon. During the postoperative period the patient were allowed to bear partial weight with the assistance of crutches for 6 weeks. At the fourth week, light stretches begin with assistance of the physical therapist. Brace immobilization is not utilize at all, instead detail instruction are provide to the patient to avoid simultaneous hip flexion and knee extension. Subjective outcome measures included: the single assessment numeric evaluation (SANE); I-Holt 12 and KJOC hip scores. Clinical data was obtained from the electronic medical records. Results: Mean patient age was 52 years (range 29-69). The injury was chronic (> 6 weeks) in 55% of the patients. Mean length of follow-up was 32 months ( range 14-60). One patient failed repair, requiring revision surgery. The average SANE score were excellent at 97points, and representing a 43 points increase from the preoperative assessment. Similarly, the mean score for the I-Holt 12 and KJOC hip scores were very good with 99 and 83 points, respectively. In 68% of the patient the injury was sport related, and they all return to sport at an average of 7 months. Conclusion: A post-operative protocol that included immediate partial weight bearing and does not utilized immobilization brace can result in excellent subjective outcomes, high rate to return to sport in a timely matter and low failure rates. Based in our findings, brace immobilization following surgical repair of proximal hamstring appear to be excessive and may not provide additional benefit.

Objectives: Hip microinstability is an increasingly recognized source of hip pain and disability. Femoral osteochondroplasty is usually performed with direct visualization through an arthroscope, assisted with repeated fluoroscopic imaging. However, a two-dimensional representation of a three-dimensional structure is misleading and may compromise the precision of the planned osteochondroplasty. The resection can occasionally extend proximally into the Femoral Head diminishing the articular surface area available for suction seal. The purpose of this study was to determine whether proximal over-resection decreases the rotational and distractive stability of the hip joint. Methods: Six hemi-pelvises were repeatedly tested in the following conditions: (a) intact, (b) T-capsulotomy, (c) Osteochondroplasty to the physeal scar, followed by (d) 5mm and (e) 10mm proximal extension. The pelvis was secured to a metal plate and the femur was potted and attached to a multi-axial hip jig. Specimens were axially distracted with a load from 0-150N followed by 5Nm of internal and external torque at 0o, 15o, 30o, 60o, 90o of flexion. Displacement/rotation was recorded using a 3D motion tracking system. Repeated measures ANOVA was used with significance set at p<0.05. Results: Proximal extension of the resection by 5mm and 10mm increased axial instability at every angle of flexion tested, with the greatest increase observed at higher angles of flexion,p<0.05. T-capsulotomy alone increased both internal and external rotation at all angles of flexion, p<0.05. Subsequent resection and extension of the resection did not significantly increase rotational instability compared to the capsulotomy state. Conclusion: Extending the osteochondroplasty proximally into the femoral head compromises the distractive stability of the hip joint, but doesn’t not effect hip rotational stability. Clinically, this highlights the importance of accuracy when performing femoral osteochondroplasty to minimize proximal extension that may increase iatrogenic instability of the hip joint, leading to reduced post-operative outcomes.

Background: Despite advances in surgical techniques, implant technology, and biological augmentation, one innate limitation to meniscus healing is lack of vascularity. Ability to quantify meniscal vascularity has been limited with previous techniques, and minimal data exists describing differential vascular zones in the skeletally immature meniscus. Purpose/Hypothesis: The objective of this study is to use quantitative contrast-enhanced magnetic resonance imaging (MRI) to compare meniscal vascularity in pediatric cadaveric specimens to adults. We hypothesize that the developing meniscus has greater and more uniform vascularity throughout all zones. Methods: We utilized 10 fresh-frozen human cadaveric knees (5 immature knees, age 0-6 months; 5 mature knees, age 34-67 years). Gadolinium-enhanced MRI was performed using a previously established vascularity quantification protocol. Regions of interest corresponding to peripheral and central zones of the meniscus were identified on pre-contrast coronal images, and signal enhancement (normalized against background tissue) was compared between pre-and post-contrast images (Figure 1). Results: Quantitative MRI demonstrated increased perfusion in the peripheral zones compared to the central zones (2.3:1 in immature knees and 3:1 in mature knees) in the medial and lateral menisci separately, and both menisci aggregated. Overall, the medial and lateral menisci had similar levels of perfusion in all specimens (45.9% ± 8.3% medial vs. 54.1% ± 8.3% lateral in immature knees; 50.5% ± 11.3% medial vs. 49.5% ± 11.3% lateral in mature knees). Immature specimens demonstrated greater overall normalized meniscal signal uptake, with the 0-month specimen demonstrating the greatest proportional signal enhancement. Conclusion: While blood flow to peripheral zones is greater than to central zones in both immature and adult menisci, younger menisci receive proportionally greater overall blood flow compared to adults, including greater blood flow to the inner zone, challenging the conventional wisdom of the central zone being avascular. As younger patients become increasingly active in sports, thorough understanding of the immature meniscus is required. Greater overall vascularity, including centrally, to the developing meniscus suggests improved healing potential following injury, and further encourages meniscal preservation when possible. Figure 1. Analysis of meniscal vascularity using contract-enhanced magnetic resonance imaging. A:Schematic drawing of peripheral and central zones of the medial and lateral menisci used for quantification.B:Mid-coronal images showing pre-and post contract images with ROIs delineated in adult and pediatric specimens; there is significatly increased perfusion to the epiphysis in the immature knee. Figure 2. Quantification of mensical vascularity in each specimen Comparsion of relative vascularity of peripheral versus central zones shows significantly greater blood flow to outer zone across all specimens.Quantification of total vascular contribution from the medial and lateral menisci aggregated showed a trend towards greater proportional blood flow in younger specimens.

Background: Although vascularity plays a critical role in healing after ulnar collateral ligament (UCL) reconstruction, intraosseous blood flow to the medial epicondyle (ME) and sublime tubercle remains undefined. Purpose: To quantify vascular disruption caused by tunnel drilling with the modified Jobe and docking techniques for UCL reconstruction. Study Design: Controlled laboratory study. Methods: Eight matched pairs (16 specimens) of fresh-frozen cadaveric upper extremities were randomized to 1 of 2 study groups: docking technique or modified Jobe technique. One elbow in each pair underwent tunnel drilling by the assigned technique, while the contralateral elbow served as a control. Pregadolinium and postgadolinium magnetic resonance imaging were performed to quantify intraosseous vascularity within the ME, trochlea, and proximal ulna. Three-dimensional computed tomography (CT) and gross dissection were performed to assess terminal vessel integrity. Results: Ulnar tunnel drilling had minimal impact on vascularity of the proximal ulna, with maintenance of >95% blood flow for each technique. Perfusion in the ME was reduced 14% (to 86% of baseline) for the docking technique and 60% (to 40% of baseline) for the modified Jobe technique (mean difference, 46%; P = .029). Three-dimensional CT and gross dissection revealed increased disruption of small perforating vessels of the posterior aspect of the ME for the modified Jobe technique. Conclusion: Although tunnel drilling in the sublime tubercle appears to have a minimal effect on intraosseous vascularity of the proximal ulna, both the docking and modified Jobe techniques reduce flow in the ME. This reduction was 4 times greater for the modified Jobe technique, and these findings have important implications for UCL reconstruction surgery. Clinical Relevance: As the rate of revision UCL reconstructions continues to rise, investigation into causes for failure of primary surgery is needed. One potential cause is poor tendon-to-bone healing due to inadequate vascularity. This study quantifies the amount of vascular insult that is incurred in the ME during UCL reconstruction. While vascular insult is only one of many factors that affects the surgical success rate, surgeons performing this procedure should be mindful of this potential for vascular disruption.

Background: The arterial supply to the chondroepiphysis is of paramount importance for proper nutrition and development. Previous animal studies had demonstrated that ischemic necrosis of the chondroepiphysis plays an important role in subsequent development of osteochondritis dissecans (OCD). Previous studies using susceptibility weighted imaging, a magnetic resonance image (MRI) sequence, demonstrated a pattern of disappearance of the arterial system over time at predilection sites for OCD lesions. The purposed of this study is to quantify distribution of the arterial perfusion in different zones of the immature distal femoral chondroepiphysis. Methods: We utilized 5 fresh frozen skeletally immature human cadaver knees (aged 0-6 months). The superficial femoral artery was cannulated proximal to the knee joint and major arteries distal to the knee joint were tied off. For volumetric analysis, comparisons were performed between contrast-enhanced and pre-contrast MRI. Regions of interest were developed to quantify the contrast enhancement in different zones of the chondroepiphysis, excluding the secondary ossification center. (Fig.1) Results: Quantitative MRI analysis demonstrated equivalent enhancement within the medial and lateral condyles in the 5 month and one of the 2 month specimens. The 0 month and 6 month specimens demonstrated greater enhancement in the medial condyle. One of the 2 months specimen demonstrated greater perfusion in the lateral condyle. The distal condyle analysis demonstrated equivalent enhancement in the 0 month, one of the 2 months and the 6 months specimens. The 5 month specimen demonstrated greater enhancement in the lateral distal condyle. The other 2 months specimen demonstrated greater enhancement in the medial distal condyle. The posterior condyle analysis demonstrated greater enhancement in the posterior lateral condyle in one of the 2 month specimen, and the 5 month and the 6 month specimens. The 0 month specimen demonstrated greater enhancement in the medial side. The other 2 month specimen demonstrated equivalent enhancement between medial and lateral side. Analyzing the medial condyle revealed equivalent enhancement in the medial and lateral zone in the 5 month and 6 month specimens. The 0 month specimen demonstrated greater enhancement laterally. Both 2 months specimens demonstrated greater enhancement in the medial side. Conclusion: This study expands the knowledge on the vascularity of the developing distal femoral chondroepiphysis, which may have an impact on our future understanding of OCD etiology, physeal growth, and peri-articular infections. The majority of the specimens demonstrated diminished perfusion in the posterior aspect of the medial femoral condyle when compare to the lateral posterior condyle. This is where the predilected area for the development of OCD lesions is located. Future studies in human and other mammals susceptible to knee OCD, along with the ongoing development of animal models of OCD will benefit from this information.