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Background: Increased humeral retrotorsion (HRT) has been found to be a risk factor for ulnar collateral ligament (UCL) tears in baseball players. Recent work has demonstrated the age of 11 years as a potential watershed age for HRT development. Hypothesis: In a group of baseball pitchers with UCL injuries, athletes who started pitching before the age of 10 years will demonstrate significantly more dominant limb humeral retrotorsion (DHRT) when compared with a group of baseball pitchers who reported starting pitching at 10 years or older. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 84 baseball pitchers with a diagnosed UCL injury were divided into 2 groups based upon the age at which participants began pitching: 33 players reporting a starting pitching age of 10 years or older (group 1) were compared with 51 baseball pitchers reporting a starting pitching age under 10 years (group 2). Participants' DHRT and nondominant limb humeral retrotorsion (NDHRT) were measured using diagnostic ultrasound. Independent t tests were run to compare mean group differences of all patient data, starting pitching age, age at time of injury, DHRT, NDHRT, and humeral retrotorsion difference (HRTdiff). Results: There were no significant differences between groups with regard to age at time of injury, height, weight, or playing years' experience. There was a statistically significant difference in the participant-reported starting pitching age. Significant differences between groups were noted for DHRT (group 1: 20.0°± 9.4°, group 2: 14.5°± 10.3°, P =.015) and for NDHRT (group 1: 38.6°± 8.8°, group 2: 32.9°± 9.5°, P =.007). No significant differences between groups were found for HRTdiff (P =.940). Conclusion: Baseball pitchers with a UCL injury who reported a starting pitching age younger than 10 years demonstrated significantly greater DHRT and NDHRT when compared with UCL-injured baseball pitchers who reported a starting pitching age at 10 years or later. The results of this study demonstrate that a younger starting pitching age results in increased HRT in players with UCL injuries. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament reconstruction is becoming more common in skeletally immature individuals, and it may be performed with transphyseal or physeal-sparing techniques. A number of studies have assessed the outcomes of these techniques, but there is a need to systematically evaluate the pooled data from these studies. Purpose: To compare the differences in demographics and outcomes of transphyseal and physeal-sparing techniques by assessing (1) demographics, (2) incidence of growth disturbances, and (3) graft survivorship in the pediatric population. Study Design: Systematic review. Methods: A thorough review of 3 databases was performed to identify all studies that evaluated outcomes after pediatric reconstruction based on transphyseal or physeal-sparing techniques. After completing our search and cross-referencing for additional sources, 43 reports were identified for this review. Reports were analyzed for differences in demographics as well as incidence of leg-length discrepancies, angular deformities, and graft survivorship. After review of manuscripts, 27 studies were included for review (21 transphyseal and 6 physeal-sparing studies). Results: Those who had transphyseal reconstruction were more likely to be female (39% vs 20%; P = .0001), while those with the physeal-sparing surgery were younger (12 vs 13.5 years of age; P = .0001). The transphyseal and physeal-sparing cohorts demonstrated similar incidence rates of leg-length discrepancies (0.81% vs 1.2%, respectively; P = .64) and angular deformities (0.61% vs 0%, respectively; P = .36). The transphyseal and physeal-sparing cohorts also showed similar rates of rerupture (6.2% vs 3.1%, respectively; P = .11). Conclusion: Although the study groups were not well matched with regard to age and sex, our results show that these surgical techniques have no differences in incidence of growth disturbances or graft survivorship. Younger males tend to undergo physeal-sparing reconstruction. Future research should focus on long-term outcome metrics with the physeal-sparing techniques, as there remains a paucity of studies regarding them. [ABSTRACT FROM AUTHOR]

Background: An anatomical medial knee reconstruction has not been described in the literature. Hypothesis: Knee stability and ligamentous load distribution would be restored to the native state with an anatomical medial knee reconstruction. Study Design: Controlled laboratory study. Methods: Ten nonpaired cadaveric knees were tested in the intact, superficial medial collateral ligament and posterior oblique ligament-sectioned, and anatomically reconstructed states. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of knee flexion with a 10-N°m valgus load, 5-N°m external and internal rotation torques, and 88-N anterior and posterior drawer loads. A 6 degrees of freedom electromagnetic motion tracking system measured angulation and displacement changes of the tibia with respect to the femur. Buckle transducers measured the loads on the intact and reconstructed proximal and distal divisions of the superficial medial collateral ligament and the posterior oblique ligament. Results: A significant increase was found in valgus angulation and external rotation after sectioning the medial knee structures at all tested knee flexion angles. This was restored after an anatomical medial knee reconstruction. The authors also found a significant increase in internal rotation at 0°, 20°, 30°, and 60° of knee flexion after sectioning the medial knee structures, which was restored after the reconstruction. A significant increase in anterior translation was observed after sectioning the medial knee structures at 20°, 30°, 60°, and 90° of knee flexion. This increase in anterior translation was restored following the reconstruction at 20° and 30° of knee flexion, but was not restored at 60° and 90°. A small, but significant, increase in posterior translation was found after sectioning the medial knee structures at 0° and 30° of knee flexion, but this was not restored after the reconstruction. Overall, there were no clinically important differences in observed load on the ligaments when comparing the intact with the reconstructed states for valgus, external and internal rotation, and anterior and posterior drawer loads. Conclusion: An anatomical medial knee reconstruction restores near-normal stability to a knee with a complete superficial medial collateral ligament and posterior oblique ligament injury, while avoiding overconstraint of the reconstructed ligament grafts. Clinical Significance: This anatomical medial knee reconstruction technique provides native stability and ligament load distribution in patients with chronic or severe acute medial knee injuries. [ABSTRACT FROM AUTHOR]

Background: Despite the growing popularity of all-inside meniscal repair devices, concerns remain about their fixation strength. It is also unclear which of these devices have the most ideal biomechanical properties. Purpose: To compare the biomechanical properties of 3 all-inside meniscal repair devices: the Meniscal Cinch, Ultra FAST-FIX, and MaxFire. Study Design: Controlled laboratory study. Methods: Twenty-seven human cadaveric menisci (3 groups of 9) were repaired using 3 different meniscal repair devices. The repaired menisci were then subjected to cyclic loading and load-to-failure testing. Gap formation and ultimate load to failure were measured. Results: Six of the devices failed during cyclic testing, 4 in the MaxFire group (44%), 1 in the Ultra FAST-FIX group (11%), and 1 in the Meniscal Cinch group (11%). After 1 cycle, there was a trend toward larger gap formation in the MaxFire group (3.65 mm) compared with the Meniscal Cinch group (2.12 mm, P = .05). After 100 cycles, group differences were found in gap formation (P = .03), with the MaxFire group exhibiting greater displacement (6.70 mm) than the Ultra FAST-FIX group (3.59 mm). After 500 cycles, group differences in gap formation (Meniscal Cinch, 5.94; Ultra FAST-FIX, 4.74 mm; Max Fire, 7.19 mm) did not reach statistical significance (P = .20). A trend was found toward higher ultimate load to failure in the Ultra FAST-FIX (86.1 N) and Meniscal Cinch (85.3 N) groups compared with the MaxFire group (64.5 N, P = .06). Stiffness was also higher in the Ultra FAST-FIX (25.2 N/mm) and Meniscal Cinch (25.5 N/mm) groups than the MaxFire group (16.3 N/mm, P = .02). Conclusion: The Meniscal Cinch and Ultra FAST-FIX devices have more desirable biomechanical properties than the MaxFire as demonstrated by higher stiffness and a lower failure rate during cyclic testing. Clinical Relevance: The Meniscal Cinch and Ultra FAST-FIX devices may be more desirable implants for use during all-inside meniscal repair as they have superior biomechanical properties when compared with the MaxFire device. [ABSTRACT FROM AUTHOR]

Background: Impact injury to articular cartilage can lead to posttraumatic osteoarthritis. Hypotheses: This study tests the hypotheses that (1) chondrocyte injury occurs after impact at energies insufficient to fracture the cartilage surface, and that (2) cartilage injury patterns vary with impact energy, time after injury, and cartilage thickness. Study Design: Controlled laboratory study. Methods: Fresh bovine osteochondral cores were randomly divided into 5 groups: (1) control, (2) 0.35 J, (3) 0.71 J, (4) 1.07 J, and (5) 1.43 J impact energies. Cores were subjected to computer-controlled impact loading and full-thickness sections were then prepared and incubated in Dulbecco's Modified Eagle's Medium/F12 at 37°C. Adjacent sections were harvested 1 and 4 days after impact for viability staining and fluorescent imaging. The area of dead and living chondrocytes was quantified using custom image analysis software and reported as a percentage of total cartilage area. Results: The highest impact energy fractured the cartilage in all cores (1.43 J, n 5 17). Seventy-three percent and 64% of the osteochondral cores remained intact after lower energy impacts of 0.71 J and 1.07 J, respectively. At lower energy levels, fractured cores were thinner (P\.01) than those remaining intact. In cores remaining intact after impact injury, chondrocyte death increased with increasing impact energy (P\.05) and with greater time after impact (P\.05). A progressive increase in dead cells near the bone/cartilage interface and at the articular surface was observed. Conclusion: These data showing progressive chondrocyte death after impact injury at energies insufficient to fracture the cartilage surface demonstrate a potential need for early chondroprotective therapy. Clinical Relevance: These data show that efforts to reduce chondrocyte morbidity after joint injury may be a useful strategy to delay or prevent the onset of posttraumatic osteoarthritis. [ABSTRACT FROM AUTHOR]

Background: Double-bundle anterior cruciate ligament (ACL) reconstruction has several potential advantages over single-bundle reconstruction with hamstring tendons. However, there are still controversies regarding tunnel placement in tibial and femoral attachments. Hypothesis: The macroscopically normal ACL consists of small bundles about 1 mm in diameter. Detailed observation of the divided smaller bundles will achieve better understanding of the tunnel placement in anatomic ACL reconstruction. Study Design: Descriptive laboratory study. Methods: This study used 20 cadaveric knees. The ACL was divided into anteromedial and posterolateral bundles, then separated into 10 small bundles of 2-mm diameters, with preservation of their attachment sites marked with color markers. The positional relationship between the femoral and tibial attachments of each small bundle was investigated. Results: A layered positional correlation of small bundles was found between the tibial and femoral attachments. Small bundles aligned in the anterior-posterior direction in the tibia corresponded to the bundles aligned in a high-low direction in the femur in flexion. The femoral attachment pattern was relatively similar in each specimen; however, the tibial attachment showed 2 patterns: an oblique type (12 of 20) and a transverse type (8 of 20). The posterior portion of the posterolateral bundle was separately attached to the medial and lateral portions of the tibial attachment. There was no fibrous insertion in the center of the posterior portion of the ACL tibial attachment in any specimen. In this bare area, there was fat tissue and vascular bundles. Conclusion: Small bundles constituting the ACL showed a relatively layered arrangement between 2 attachments. The tibial attachment showed 2 patterns of oblique and transverse types, and the vascular bundles were located in the center of the posterolateral bundle. Clinical Relevance: The results of this study of the normal ACL will provide insights for surgeons when placing grafts during anatomic ACL reconstruction. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to elucidate the degree of biceps anchor displacement that occurs when specific zones of the superior labrum are detached from the glenoid. Study Design: Descriptive laboratory study. Methods: Twelve cadaveric scapulae with intact labrums were prepared by removing the surrounding musculature with the labrum, biceps anchor, and biceps tendon carefully preserved. Pulleys were used to apply traction in 3 different directions-superior, lateral, and combined posterior/superior/lateral, to simulate the "peel-back" mechanism-while a continuous 1.13 kg of traction was applied to the biceps tendon. Labral tears were created by sharp incisions in isolation and in combinations of 3 zones defined relative to the glenoid fossa: anterior, posterior, or superior. The displacement of the biceps anchor (position of the marker after the simulated lesion relative to the marker position with the labrum intact) was measured relative to a rigid reference frame. Results: The greatest degree of displacement occurred with the sectioning of all 3 zones, followed by the sectioning of 2 adjacent zones. Superior traction created the least displacement in all combinations, while lateral traction created maximal displacement, with one exception: in the setting of anterosuperior/superior lesions, maximal displacement was observed using the peel-back mechanism. Conclusion: Biceps anchor displacement, particularly the degree and direction of displacement, is affected by the labral detachment pattern. All 3 labral zones assessed in this study have important biomechanical contributions to biceps anchor displacement. Clinical Significance: These findings have important implications relating to the clinician's arthroscopic assessment of superior labrum anterior and posterior (SLAP) tears, as well as the determination of need for stabilization. This information is particularly useful when treating SLAP tears in certain laborers and athletes, whose activities may cause specific biceps anchor displacement patterns. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament reconstruction with a double-bundle technique requires exact tunnel positioning. Reference values for the anatomic insertions are necessary for radiographic intra- and postoperative control and fluoroscopybased navigation. Hypothesis: The femoral and tibial insertions of the anteromedial bundle (AMB) and posterolateral bundle (PLB) of the anterior cruciate ligament can be described using standardized computed tomography scans. Study Design: Descriptive laboratory study. Methods: The insertion sites of the AMB and PLB were macroscopically identified and tagged by copper wire in 12 specimens. Computed tomography scans with predefined reconstructions were performed. Femorally, the geometric center of the insertions were determined in the sagittal view and described in a deep-high 10 x 10 grid. Tibially, the insertions were described as the ratio between the geometric center of the insertion sites with respect to the mediolateral and sagittal diameter of the tibia in frontal and sagittal reconstruction, respectively. The tibial insertions were described using a 10 x 10 grid in axial orientation. Results: The geometric midpoints of the insertion areas at the femur of the AMB and PLB were located on the reticule at x = 21% ± 3% and y = 22% ± 2% for the AMB and x = 27% ± 3% and y = 45% ± 3% for the PLB. In the sagittal plane, the center of the tibial insertion was located at 41% ± 3% and 52% ± 3% of the tibial diameter from the anterior border for the AMB and PLB, respectively. The geometric centers of the tibial insertions in axial view were x = 52% ± 2% and y = 37% ± 3% for the AMB and x = 50% ± 2% and y = 48% ± 3% for the PLB. Conclusion: The insertion site characteristics of the AMB and PLB can be evaluated by predefined reconstructions of computed tomography scans. Clinical relevance: These results can serve as orientation landmarks for intra- and postoperative radiographic control and fluoroscopic-based navigation. [ABSTRACT FROM AUTHOR]

Background: Humeral head defects have been associated with failed anterior shoulder instability repairs. Quantitative data are required to determine (1) the critical defect size for consideration of surgical repair and (2) the ability of proposed repair techniques to restore normal joint function. Hypotheses: Increasing defect size will decrease stability and anterior translation before dislocation. Stability will decrease in shoulder positions where the defect is oriented in line with the anterior glenoid. Osteoarticular repair will restore joint stability to intact shoulder level. Study design: Controlled laboratory study. Methods: A robotic/universal force-moment sensor testing system was used to apply joint compression (22 N) and an anterior load (40 N) to cadaveric shoulders (n = 9) with all soft tissues removed (intact) at joint orientations with 60° of glenohumeral abduction and 0° and 60° of external rotation. Four posterolateral osteoarticular defects were created (12.5%, 25.0%, 37.5%, and 50.0% defect) followed by an osteoarticular allograft transplantation (repair). The loading protocol was repeated in each shoulder state for both joint orientations. The anterior translation and stability ratio (anterior load/compressive load) were recorded before dislocation. Results: All shoulders dislocated at 60° of external rotation with all sizes of defects. At 0° of external rotation, shoulders with the 12.5% to 37.5% defects did not dislocate, and only 2 shoulders with the 50.0% defect dislocated. At 60° of external rotation, the 25.0% defect and 37.5% defect had significantly less anterior translation before dislocation, as compared with the intact (P < .05), both of which became similar to the intact after repair (P > .05). The stability ratio at 60° of external rotation significantly decreased in the 25.0% and 37.5% defects, as compared with the intact (P < .05), representing a 25% and 40% decrease in stability ratio. The stability ratio became similar to intact after repair (P > .05). Conclusion: The size and orientation of the defect has important contributions to glenohumeral joint function. Increasing defect size required less anterior translation before dislocation and decreased the stability ratio, thereby increasing the risk of recurrent instability. Clinical Relevance: Defects as small as 12.5% of the humeral head have biomechanical consequences that may affect joint stability. In addition, shoulders with large osteoarticular defects (37.5% or 50.0%) may benefit from osteoarticular allograft transplantation to restore shoulder stability. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) graft failure is an uncommon but devastating event after reconstruction, and risk factors for graft failure are not well understood. Hypothesis: Returning to a high activity level after ACL reconstruction and use of an allograft are risk factors for ACL graft failure. Study Design: Case-control study; Level of evidence, 3. Methods: Twenty-one patients with ACL graft failure were identified over a 2-year period. Forty-two age- and sex-matched controls were identified over the same period. A 1:2 matched case-control design was used to evaluate activity level after reconstruction and graft type as risk factors for ACL graft failure. Logistic regression analysis was used to determine odds ratios for activity level after reconstruction and for graft type among cases and controls. Association (interaction) between activity level after reconstruction and graft type was evaluated comparing stratum-specific odds ratios. Results: Univariate logistic regression models showed an increased odds of ACL graft failure for those with high activity level compared with low activity level (odds ratio [OR], 5.53; 95% confidence interval [CI], 1.18-28.61; P = .03) and for allografts compared with autografts (OR, 5.56; 95% CI 1.55-19.98; P = .009). A bivariate logistic regression model showed a 35% change in the odds ratio for activity level (OR, 4.33; 95% CI, 0.89-21.16; P = .07) and a 13% change in the odds ratio for allograft compared with autograft (OR, 4.93; 95% CI, 1.34-18.20; P = .02). Stratum-specific odds ratios between activity level and graft type show a multiplicative interaction between higher activity level and allograft for much greater odds of ACL graft failure. Conclusion: Higher activity level after reconstruction and allograft use for reconstruction are risk factors for ACL graft failure. Stratum-specific odds ratios show a multiplicative interaction between higher activity level after ACL reconstruction and allograft use, greatly increasing the odds for ACL graft failure. [ABSTRACT FROM AUTHOR]

Background: A transtendon interimplant mattress repair along the medial row for partial-thickness rotator cuff repairs has been described with clinical success. However, the biomechanical characteristics for such a repair have not been elucidated. Hypothesis: A knotless interimplant mattress repair may show improved or equivalent load and strain characteristics, compared with a repair using isolated mattress repairs over each of 2 anchors. Study Design: Controlled laboratory study. Methods: Seven matched pairs of human cadaveric shoulders were dissected. Articular-sided tears were created involving 50% of the supraspinatus footprint. In 7 shoulders, repairs were performed with mattress configurations isolated over each of 2 anchor sites (control group). In 7 contralateral shoulders, a knotless interimplant mattress suture configuration was employed creating bridging sutures between implants. For all specimens, a materials-testing machine was used to cyclically load each repair from 10 to 180 N for 30 cycles; each repair was then loaded to failure. A deformation rate of 1 mm per second was employed for all tests. A video-digitizing system was employed to quantitatively measure the gap formation and strain on the footprint area of the repair. For detecting gap formation, 7 matched pairs were necessary for achieving a power of at least 90%. Results: During cyclic loading, gap formation at the anterior tendon was significantly lower in the control group (P < .05) but did not exceed 0.5 mm. There were no significant differences for linear stiffness, hysteresis, and strain between the 2 constructs. During tensile load-to-failure testing, there were no significant differences at yield load between the control and knotless techniques (293.90 ± 132.72 N and 320.38 ± 237.01 N, respectively; P > .05). There were no differences for stiffness, ultimate load, and energy absorbed to failure between the 2 repairs (P > .05). Gap formation in 3 regions was not significantly different between groups at yield and ultimate loads (P > .05). The anterior regions of the repair were the first to fail in all constructs. Conclusion: A transtendon interimplant mattress rotator cuff repair for partial articular-sided tendon tears involving 50% of the footprint has biomechanical characteristics similar to those of a repair employing 2 isolated mattress configurations. An interimplant mattress repair can protect tendon strain; it also exhibits yield loads that exceed those typically experienced in the early postoperative period. Clinical Relevance: A medial-row interimplant mattress repair configuration that is knotless may facilitate repair without compromising biomechanical characteristics. [ABSTRACT FROM AUTHOR]

Background: Fibrous connections and fibrofatty tissue between the layers of the medial retinaculum have prevented accurate definition of the true anatomy of the medial patellofemoral ligament. This has led to confusion about the origin, form, course, and insertion of this structure. Hypothesis: The medial patellofemoral ligament is a discrete structure that can be approached, isolated, and definitively described. Study Design: Descriptive laboratory study. Methods: Fifty fresh or fresh-frozen human knee specimens were carefully dissected to determine the precise anatomy of the medial patellofemoral ligament. Results: Present in all specimens, the medial patellofemoral ligament was found to have 2 origins: (1) a transverse 10.6-mm origin from the bony groove between the medial epicondyle and the adductor tubercle, and (2) an oblique decussation originating from the proximal 30 mm of the leading edge of the superficial medial collateral ligament. The 2 origins combined and inseparably joined the vastus medialis obliquus tendon and inserted securely into the ventral edge of the bony patella over a span of 28.2 ± 5.6 mm adjacent to the articular surface of the patella. The length from the femoral origin to the patella was 59.8 ± 4.8 mm. The key to the dissection was finding the fine capsular vessels from the descending genicular artery that is between layers I and II of the medial retinacular structures. Conclusion: The medial patellofemoral ligament is a constant structure in la‡yer II, with a complex anatomy that can be defined by careful dissection using the capsular branches of the descending genicular artery as a guide. Clinical Relevance: This study provides essential new information that could help surgeons safely locate the medial patellofemoral ligament and repair or reconstruct it anatomically. [ABSTRACT FROM AUTHOR]

Background: There is little scientific evidence available regarding the pathologic basis for chronic groin injury in athletes, a known difficult clinical problem. Hypothesis: Histological analysis of the superior pubic ramus in athletes with diagnosed chronic groin injury may reveal the nature of the pathologic process. Study Design: Case series; Level of evidence, 4. Methods: Ten athletes with a diagnosis of chronic groin injury by clinical criteria (at least 6 weeks of pain) and magnetic resonance imaging criteria (unequivocal increase in T2 signal intensity) underwent bone biopsy of the superior pubic ramus. The biopsy site was located in the parasymphyseal region in the area of increased magnetic resonance image signal intensity. Histologic analysis of the specimens was then undertaken. Results: Evidence of new woven bone was seen in all biopsy specimens. Signs of old bony injury were seen in 8 of the 10 specimens. There was no evidence of inflammation or osteonecrosis. Conclusion: Histologic analysis of bone biopsy specimens taken from the parasymphyseal pubic bone region with magnetic resonance imaging T2-weighted increased signal intensity of athletes diagnosed by clinical and magnetic resonance imaging criteria as having chronic groin injury demonstrates new woven bone formation. This is consistent with the athlete having a bone stress injury that may contribute significantly to athletic groin pain. [ABSTRACT FROM AUTHOR]