Preoperative planning with three-dimensional CT vs. three-dimensional magnetic resonance imaging does not change surgical management for shoulder instability.

Background: This study aims to determine the effect of time and imaging modality (three-dimensional (3D) CT vs. 3D magnetic resonance imaging (MRI)) on the surgical procedure indicated for shoulder instability. The hypothesis is there will be no clinical difference in procedure selection between time and imaging modality. Methods: Eleven shoulder surgeons were surveyed with the same ten shoulder instability clinical scenarios at three time points. All time points included history of present illness, musculoskeletal exam, radiographs, and standard two-dimensional MRI. To assess the effect of imaging modality, survey 1 included 3D MRI while survey 2 included a two-dimensional and 3D CT scan. To assess the effect of time, a retest was performed with survey 3 which was identical to survey 2. The outcome measured was whether surgeons made a "major" or "minor" surgical change between surveys. Results: The average major change rate was 14.1% (standard deviation: 7.6%). The average minor change rate was 12.6% (standard deviation: 7.5%). Between survey 1 to the survey 2, the major change rate was 15.2%, compared to 13.1% when going from the second to the third survey (P = .68). The minior change rate between the first and second surveys was 12.1% and between the second to third interview was 13.1% (P = .8). Discussion: The findings suggest that the major factor related to procedural changes was time between reviewing patient information. Furthermore, this study demonstrates that there remains significant intrasurgeon variability in selecting surgical procedures for shoulder instability. Lastly, the findings in this study suggest that 3D MRI is clinically equivalent to 3D CT in guiding shoulder instability surgical management. Conclusion: This study demonstrates that there is significant variability in surgical procedure selection driven by time alone in shoulder instability. Surgical decision making with 3D MRI was similar to 3D CT scans and may be used by surgeons for preoperative planning.

Total Hip Replacement Interrupted by Intraoperative Arrest with a Final Component in Place: A Case Report.

No consensus recommendations exist as to the management of implants exposed during an interrupted total hip arthroplasty (THA). Given the infrequency of such events, documentation of successful outcomes in single case reports aids in decision-making. A 71-year-old male with a history of coronary artery disease and a BMI of 39.5 went into ventricular fibrillation half-way through a THA, after placement of a cementless acetabular component but before femoral preparation could begin. Continuation of the planned arthroplasty was aborted, the patient's wound was packed with sterile sponges and covered with an iodoform dressing, and he was flipped supine for CPR. He returned to the OR 6-hours following his arrest and his arthroplasty was completed with the original acetabular implant left in place. The patient was placed empirically on 2 weeks of IV vancomycin and 3 months of oral doxycycline based on infectious disease recommendations, and healed uneventfully. While validation of our strategy is challenging due to the infrequent nature of this event, it is hoped that this description and discussion may provide a template to those who encounter a similar challenging situation.

Surgical treatment for recurrent shoulder instability: factors influencing surgeon decision making.

BACKGROUND: The optimal surgical approach for recurrent anterior shoulder instability remains controversial, particularly in the face of glenoid and/or humeral bone loss. The purpose of this study was to use a contingent-behavior questionnaire (CBQ) to determine which factors drive surgeons to perform bony procedures over soft tissue procedures to address recurrent anterior shoulder instability. METHODS: A CBQ survey presented each respondent with 32 clinical vignettes of recurrent shoulder instability that contained 8 patient factors. The factors included (1) age, (2) sex, (3) hand dominance, (4) number of previous dislocations, (5) activity level, (6) generalized laxity, (7) glenoid bone loss, and (8) glenoid track. The survey was distributed to fellowship-trained surgeons in shoulder/elbow or sports medicine. Respondents were asked to recommend either a soft tissue or bone-based procedure, then specifically recommend a type of procedure. Responses were analyzed using a multinomial-logit regression model that quantified the relative importance of the patient characteristics in choosing bony procedures. RESULTS: Seventy orthopedic surgeons completed the survey, 33 were shoulder/elbow fellowship trained and 37 were sports medicine fellowship trained; 52% were in clinical practice ≥10 years and 48% <10 years; and 95% reported that the shoulder surgery made up at least 25% of their practice. There were 53% from private practice, 33% from academic medicine, and 14% in government settings. Amount of glenoid bone loss was the single most important factor driving surgeons to perform bony procedures over soft tissue procedures, followed by the patient age (19-25 years) and the patient activity level. The number of prior dislocations and glenoid track status did not have a strong influence on respondents' decision making. Twenty-one percent glenoid bone loss was the threshold of bone loss that influenced decision toward a bony procedure. If surgeons performed 10 or more open procedures per year, they were more likely to perform a bony procedure. CONCLUSION: The factors that drove surgeons to choose bony procedures were the amount of glenoid bone loss with the threshold at 21%, patient age, and their activity demands. Surprisingly, glenoid track status and the number of previous dislocations did not strongly influence surgical treatment decisions. Ten open shoulder procedures a year seems to provide a level of comfort to recommend bony treatment for shoulder instability.

Unilateral hypertrophy of the labia minora: A case series.

Asymmetric hypertrophy of the labia minora is a variant of normal anatomy that has not been described in the pediatric dermatology literature. Although often asymptomatic, in some cases, it can cause functional, emotional, and psychological problems. We report the clinical characteristics and outcomes of four children who presented with unilateral labium minus hypertrophy. This case series aims to establish awareness of this condition among pediatric dermatologists and provide recommendations regarding management.

Magnesium ring device to restore function of a transected anterior cruciate ligament in the goat stifle joint.

A bioresorbable, mono-crystalline magnesium (Mg) ring device and suture implantation technique were designed to connect the ends of a transected anterior cruciate ligament (ACL) to restabilize the knee and load the ACL to prevent disuse atrophy of its insertion sites and facilitate its healing. To test its application, cadaveric goat stifle joints were evaluated using a robotic/universal force-moment sensor testing system in three states: Intact, ACL-deficient, and after Mg ring repair, at 30°, 60°, and 90° of joint flexion. Under a 67-N anterior tibial load simulating that used in clinical examinations, the corresponding anterior tibial translation (ATT) and in-situ forces in the ACL and medial meniscus for 0 and 100 N of axial compression were obtained and compared with a control group treated with suture repair. In all cases, Mg ring repair reduced the ATT by over 50% compared to the ACL-deficient joint, and in-situ forces in the ACL and medial meniscus were restored to near normal levels, showing significant improvement over suture repair. These findings suggest that Mg ring repair could successfully stabilize the joint and load the ACL immediately after surgery, laying the framework for future in vivo studies to assess its utility for ACL healing. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2001-2008, 2016.

Structure modeling of the glenoid: Relevance to shoulder arthroplasty.

We applied shape modeling and principal component analysis (PCA) to discover glenoid bone structural relationships relevant to improving glenoid prosthesis features, fixation, and instrumentation. Knowledge of external bone morphology guides prosthesis shape and positioning, while internal bone morphology and bone density influence fixation. CT-based modeling defined nonarthritic glenoid subchondral bone surface and internal structure. First and second principal shape components were related to size and density. Reproducible structural parameters and glenoid feature relationships were discovered. Subchondral bone surface was approximated by a circle inferiorly and a triangle superiorly with the circle's center at a reproducible point along a superior-inferior line. Glenoid vault's maximum depth was at the circle's center, and the highest bone density was in posterior glenoid. Glenoid subchondral bone surface version varied from superior to inferior, but not by sex or side. Male subchondral bone surfaces were larger and more retroverted. Even if subchondral bone surfaces are deformed by arthritis, glenoid morphology can be identified by extra-articular landmarks, permitting location of the glenoid center and scapular orientation (glenoid version). Knowledge obtained from this study directs design of novel prosthesis features and instrumentation for use without pre-op CT or computer aided surgery.

Anterior shoulder dislocation increases the propensity for recurrence: a cadaveric study of the number of dislocations and type of capsulolabral lesion.

BACKGROUND: The number of anterior shoulder dislocations that predispose to recurrence is unknown; some clinicians recommend surgical repair after the initial episode and others after multiple recurrences. The purpose of this study was to quantify the forces during successive anterior dislocations of cadaveric shoulders and to inspect the capsule and labrum afterwards, in order to assess the propensity for recurrence. MATERIALS AND METHODS: Twenty-two human cadaveric shoulders were tested using a custom cadaveric shoulder dislocation device with simulated muscle loading. Each was positioned in the apprehension position and the humerus was moved in horizontal abduction until the shoulder dislocated. The joint reaction force was measured, as was the force that developed passively in the pectoralis major muscle. Following 3 successive dislocations, each was inspected for anterior capsulolabral lesions. RESULTS: There was a significant decrease in force after the second dislocation. In 11, there was no labral avulsion and a significant decrease in force after the first dislocation. In the other 11, there was a labral avulsion and a significant decrease in force after the second dislocation. CONCLUSION: Two successive anterior shoulder dislocations may increase propensity for recurrence; but this is influenced by the type of capsulolabral lesion that occurs. No labral avulsion, likely a result of capsular stretching, may be a worse prognostic finding than labral avulsion after the initial episode.

Potential of healing a transected anterior cruciate ligament with genetically modified extracellular matrix bioscaffolds in a goat model.

PURPOSE: Biological augmentation to heal a torn anterior cruciate ligament (ACL) has gained significant interest. This study examined the potential advantages of using extracellular matrix (ECM) bioscaffolds from galactosyl-α(1,3)galactose deficient pigs to heal the transected ACL. METHODS: In 16 skeletally mature goats, the ACL in the right hindlimb was transected and repaired. In 9 of these animals, an ECM sheet was wrapped around the injury site and with an ECM hydrogel injected into the transected site. The remaining 7 animals were treated with suture repair only. The left hindlimb served as a sham-operated control. RESULTS: After 12 weeks, the healing ACL in the ECM-treated group showed an abundance of continuous neo-tissue formation, while only limited tissue growth was found after suture repair only. The cross-sectional area of the ACL from the ECM-treated group was similar to sham-operated controls (n.s.) and was 4.5 times those of the suture repair group (P < 0.05). The stiffness of the femur-ACL-tibia complexes from the ECM-treated group was 2.4 times those of the suture repair group (P < 0.05). Furthermore, these values reached 48% of the sham-operated controls (53 ± 19 N/mm and 112 ± 21 N/mm, respectively, P < 0.05). CONCLUSIONS: The application of an ECM bioscaffold and hydrogel was found to accelerate the healing of a transected ACL following suture repair in the goat model with limited tissue hypertrophy and improvement in some of its biomechanical properties. Although more work is necessary to fully restore the function of the normal ACL, these early results offer a potential new approach to aid ACL healing.

Quantification of rotator cuff tear geometry: the repair ratio as a guide for surgical repair in crescent and U-shaped tears.

INTRODUCTION: Surgical repair of symptomatic, retracted rotator cuff tears unresponsive to non-operative treatments requires closure of the tear without undue tension and reattaching the torn tendon to its former insertion site. In this study, the length of the torn tendon edge was hypothesized to be longer than the length of the humeral insertion site. The objective of this study was to quantify the discrepancy in length of the torn tendon edge and the length of the avulsed humeral insertion site. MATERIALS AND METHODS: Full thickness, rotator cuff tears that were found in twelve fresh frozen cadaver shoulders was studied. The length of the torn tendon edge, the length of the avulsed humeral insertion site and the retraction were measured using digital calipers. RESULTS: Each tear involved the supraspinatus and the infraspinatus was additionally torn in six. The size of the tear was medium in eight and large in four. The length of the torn tendon edge was always longer than the length of the avulsed humeral insertion site. Retraction was 29.9 +/- 9.3 mm (range 21-48 mm). The repair ratio, defined as the ratio of length of torn tendon edge to the length of avulsed humeral insertion site, was 2.6 +/- 0.4 (range 2.1-3.5). CONCLUSION: As only the length of the torn tendon edge equal to the length of the avulsed humeral insertion site can be repaired to bone, a repair ratio more than one precludes a simple repair and an additional repair technique such as margin convergence would be necessary for the remaining unapproximated torn tendon edge in rotator cuff tears. Repair ratio may aid in selection of the surgical repair technique of these rotator cuff tears.

Pectoralis major tendon transfers above or underneath the conjoint tendon in subscapularis-deficient shoulders. An in vitro biomechanical analysis.

BACKGROUND: Different operative techniques for transfer of the pectoralis major tendon have been proposed for the treatment of irreparable ruptures of the subscapularis tendon. The objective of this study was to compare the effects of two techniques of transferring the pectoralis major tendon (above or underneath the conjoint tendon) on glenohumeral kinematics during active abduction in a biomechanical model of a subscapularis-deficient shoulder. METHODS: Six shoulder specimens were tested with a custom dynamic shoulder testing apparatus. After the kinematics of the intact shoulder were recorded, a complete tear of the subscapularis tendon was simulated surgically. A transfer of the clavicular portion of the pectoralis major muscle to the lesser tuberosity was then performed with the transferred tendon placed either above (tendon-transfer 1) or underneath (tendon-transfer 2) the conjoint tendon. For each condition, the maximum abduction angle as well as the external rotation angle and the superoinferior and anteroposterior humeral translations at the maximum abduction angle were recorded. RESULTS: With the rotator cuff intact, the mean maximum glenohumeral abduction angle (and standard error of the mean) was 86.3 degrees +/- 2.1 degrees and the mean amount of external rotation at the maximum abduction angle was 5.5 degrees +/- 7.6 degrees . A complete tear of the subscapularis tendon decreased the mean maximum abduction angle to 40.8 degrees +/- 2.4 degrees (p < 0.001) and increased the mean external rotation to 91.8 degrees +/- 4.8 degrees (p < 0.001). The mean humeral translations in the anterior and superior directions (+3.4 +/- 0.5 and +6.3 +/- 0.3 mm, respectively) at the maximum abduction angle were also increased (p < 0.01 and p < 0.001) when compared with those in the intact shoulder. Significant differences were found in the mean maximum abduction angle as well as the mean external rotation angle and humeral translations (anterior and superior) at maximum abduction between the tendon-transfer-1 condition (63.2 degrees +/- 13.5 degrees , 82.4 degrees +/- 6.6 degrees , 4.0 +/- 1.8 mm, and 3.3 +/- 1.9 mm, respectively) and tendon-transfer-2 condition (89.5 degrees +/- 12.3 degrees , 45.7 degrees +/- 22.5 degrees , -0.6 +/- 2.0 mm, and 0.5 +/- 2.3 mm, respectively). The tendon-transfer-2 condition restored glenohumeral kinematics that were closer to those in the intact shoulder than were those resulting from the tendon-transfer-1 condition. CONCLUSIONS: Transfer of the pectoralis major tendon in subscapularis-deficient shoulders partially restored the glenohumeral kinematics of the intact shoulder. One possible explanation for the superior effect of the tendon-transfer-2 condition is that, with a pectoralis major tendon transfer underneath the conjoint tendon, the line of action of the transferred tendon is closer to that of the subscapularis muscle.

Acromial morphology: effects of suboptimal radiographs.

Acromial morphology is one of the important factors related to rotator cuff pathology, especially if there is acromial encroachment onto the supraspinatus tendon. This is the rationale for many surgeons performing an acromioplasty, based on preoperative radiographs, in their treatment of rotator cuff disease. However, geometric measurements of the acromion are dependent on the radiographic view, and suboptimal radiographs of the scapula might bias the acromial morphology on the radiographs. Our objective was to study the effect of suboptimal lateral-view radiographs of the scapula on 6 acromial angles, which have been correlated with rotator cuff pathology, by use of a computational method. Anatomic landmarks were digitized on 12 cadaveric scapulae via a spatial linkage system. A coordinate system based on the scapula was then created that allowed projection of the anatomic landmarks on the sagittal plane and simulated the optimal lateral-view radiograph of the scapula. By rotating the coordinate system in the coronal plane (cranial and caudal projections) and axial plane (anterior and posterior projections) with 5 degrees, 10 degrees, 15 degrees, and 20 degrees increments, 16 suboptimal lateral-view radiographs of the scapula were simulated. Significant differences in the 6 acromial angles (P < .01) between the optimal and suboptimal lateral-view radiographs of the scapula were found in almost every cranial and caudal projection. Rotating the projection in the axial plane did not significantly affect the acromial angles (P > .05) up to 20 degrees of rotation in the anterior and posterior direction. Of the 6 different acromial angles, the acromial slope was least affected when the projection was varied. In contrast, the anterior slope of the acromion was highly affected by errors in the projection.

Orientation feedback during simulated simple translation tests has little clinical significance on the magnitude and precision of glenohumeral joint translations.

The repeatability of shoulder instability clinical examinations has been reported to be poor, producing a large range of translations. The objective of this study was to determine the effect of providing the clinician with joint orientation feedback on the magnitude and precision of glenohumeral joint kinematics. A 6-degree of freedom magnetic tracking system was used to determine the kinematics of the humerus with respect to the scapula (n=8 cadaveric shoulders). The joints were preconditioned with simple loading tests five times. At 60 degrees of glenohumeral abduction and 0 degrees of flexion/extension, a clinician then applied an anterior and posterior load to the humerus until a manual maximum simulating a simple translation test (STT) was achieved at 0, 30, and 60 degrees of external rotation with and without angular orientation feedback of the humerus with respect to the scapula. The precision for the external rotation was within 4.3 degrees for the feedback group and 17.5 degrees for the no feedback group over all external rotations. For achieving the target external rotation of 30 degrees , there was a significant difference in precision between the feedback and no feedback groups (p<0.05). The magnitudes of the anterior translations were 18.2+/-5.3, 15.5+/-5.1, and 9.9+/-5.5 mm for the feedback group and 19.3+/-6.6, 17.5+/-4.9, and 11.5+/-5.3 mm for the no feedback group, at 0, 30, and 60 degrees of external rotation, respectively. There was a significant difference in the precision of anterior translation at 30 and 60 degrees of external rotation for 4 of 8 specimens (p<0.05). Significant differences in the precision of the posterior translation was only detected at 0 degrees of external rotation for 3 of 8 specimens (p<0.05). Based on the data obtained, providing orientation feedback to a clinician performing a simulated STT results in increased precision for not only the target external rotations but also the resulting glenohumeral translations. While providing feedback may be a necessary step to achieving precise results for experimental studies, the magnitudes of translations in the anterior and posterior directions were relatively similar for the feedback and no feedback states indicating little benefit for clinical examinations.

A biomechanical comparison of arthroscopic sliding and sliding-locking knots.

PURPOSE: To evaluate biomechanical characteristics of 3 arthroscopic sliding and sliding-locking knots and the square knot, the gold standard used in open surgery. TYPE OF STUDY: Biomechanical investigation. METHODS: Four different knot types (Weston, square, Duncan loop, and Nicky's) were tested in 5 configurations in a closed-loop system on a materials testing device. Three of the 5 knots were backed up with 3 reverse half-hitches and alternating posts and all sliding and sliding-locking knots were tied using an arthroscopic technique. Twelve knots of each configuration were tested for loop security with a 7-N preload, and for knot security with load to failure at a strain rate of 1.25 mm/second and cyclic loading of a 30-N force for 50 cycles. RESULTS: No knots subjected to the 7-N preload failed or slipped and all had similar elongation (0.1 +/- 0.1 mm) except Nicky's knot (0.3 +/- 0.2 mm). There was no significant difference in load at failure for the square knot (178 +/- 14 N), the Weston knot backed with 3 half-hitches (168 +/- 14 N), the Duncan loop (160 +/- 20 N), or Nicky's knot (148 +/- 13 N). Most knots with 3 half-hitches failed with rupture at the knot. Under cyclic loading, no knots failed and none elongated greater than an average of 0.3 mm. CONCLUSIONS: All knot configurations maintained high loop security. All sliding and sliding-locking knots backed with 3 half-hitches had load at failure comparable to the square knot. With cyclic load testing, all knots tested elongated minimally. Additionally, this study confirms that all knots, even the sliding-locking Weston knot, are best backed up with 3 half-hitches alternating posts and directions of the throws. CLINICAL RELEVANCE: Sliding and sliding-locking knots are becoming increasingly popular among arthroscopic shoulder surgeons. This study provides a biomechanical basis for the clinical use of these arthroscopic knots and compares them with the gold standard, the open square knot.

Stress and strain in the anterior band of the inferior glenohumeral ligament during a simulated clinical examination.

The objective of this research was to predict, with a finite-element model, the stress and strain fields in the anterior band of the inferior glenohumeral ligament (AB-IGHL) during application of an anterior load with the humerus abducted. The stress and strain in the AB-IGHL were determined during a simulated simple translation test of a single intact shoulder. A 6-degree-of-freedom magnetic tracking system was used to measure the kinematics of the humerus with respect to the scapula. A clinician applied an anterior load to the humerus until a manual maximum was achieved at 60 degrees of glenohumeral abduction and 0 degrees of flexion/extension and external rotation. For the computational analysis, the experimentally measured joint kinematics were used to prescribe the motion of the humerus with respect to the scapula, whereas the material properties of the AB-IGHL were based on published experimental data. The geometry of the AB-IGHL, humerus, and scapula was acquired by use of a volumetric computed tomography scan, which was used to define the reference configuration of the AB-IGHL. Strains reached 12% along the inferior edge and 15% near the scapular insertion site at the position of maximum anterior translation. During this motion, the AB-IGHL wrapped around the humerus and transferred load to the bone via contact. Predicted values for von Mises stress in the ligament reached 4.3 MPa at the point of contact with the humeral head and 6.4 MPa near the scapular insertion site. A comparison of these results to the literature suggests that the computational approach provided reasonable predictions of fiber strain in the AB-IGHL when specimen-specific geometry and kinematics with average material properties were used. The complex stress and strain distribution throughout the AB-IGHL suggests that the continuous nature of the glenohumeral capsule should be considered in biomechanical analyses. In the future, this combined experimental and computational approach will be used for subject-specific studies of capsular function and could provide quantitative data to help surgeons improve methods for the diagnosis and treatment of glenohumeral instability.

Stability and instability of the glenohumeral joint: the role of shoulder muscles.

Shoulder muscles contribute to both mobility and stability of the glenohumeral joint. To improve treatments for shoulder instability, we focused on the contribution of the shoulder muscles to glenohumeral joint stability in clinically relevant positions. Both computational and experimental models were used. A computational model of the glenohumeral joint quantified stability provided by active muscle forces in both mid-range and end-range glenohumeral joint positions. Compared with mid-range positions, the resultant joint force at end-range positions was more anteriorly directed, indicating that its contribution to glenohumeral joint stability was diminished. In end-range positions, simulated increases in rotator cuff muscle forces tended to improve stability whereas increases in deltoid or pectoralis major muscle forces tended to further decrease stability. To validate these results, a cadaveric model, simulating relevant shoulder muscles, was used to quantify glenohumeral joint stability. When infraspinatus muscle activity was decreased, compressive forces decreased. When pectoralis major muscle activity was increased, anteriorly directed forces increased. If anteriorly directed forces increase or compressive forces decrease, stability of the glenohumeral joint decreases. This cadaveric model was then used to evaluate the effect of placing the joint in the apprehension position of abduction, external rotation, and horizontal abduction. Consistent with the results of our computational model, apprehension positioning increased anteriorly directed forces. Knowledge gained from these models was then used to develop a cadaveric model of glenohumeral joint dislocation. Dislocation resulted from the mechanism of forcible apprehension positioning when the appropriate shoulder muscles were simulated and a passive pectoralis major muscle was included. Capsulolabral lesions resulted that were similar to those observed in vivo. Shoulder muscle forces are usually powerful stabilizers of the glenohumeral joint, especially in mid-range positions when the passive stabilizers are lax. However, muscle forces can contribute to instability as well. Certain muscle forces decrease glenohumeral joint stability in end-range positions. We found this to be the case with both active and passive pectoralis major forces. Improved understanding of the contribution of muscle forces not only toward stability but also toward instability will improve rehabilitation protocols for the shoulder and prove useful in the treatment of joint instability throughout the body.

Varying femoral tunnels between the anatomical footprint and isometric positions: effect on kinematics of the anterior cruciate ligament-reconstructed knee.

BACKGROUND: Knee kinematics and in situ forces resulting from anterior cruciate ligament reconstructions with 2 femoral tunnel positions were evaluated. HYPOTHESIS: A graft placed inside the anatomical footprint of the anterior cruciate ligament will restore knee function better than a graft placed at a position for best graft isometry. STUDY DESIGN: Controlled laboratory study. METHODS: Ten cadaveric knees were tested in response to a 134-N anterior load and a combined 10-N.m valgus and 5-N.m internal rotation load. A robotic universal force-moment sensor testing system was used to apply loads, and resulting kinematics were recorded. An active surgical robot system was used for positioning tunnels in 2 locations in the femoral notch: inside the anatomical footprint of the anterior cruciate ligament and a position for best graft isometry. The same quadrupled hamstring tendon graft was used for both tunnel positions. The 2 loading conditions were applied. RESULTS: At 30 degrees of knee flexion, anterior tibial translation in response to the anterior load for the intact knee was 9.8 +/- 3.1 mm. Both femoral tunnel positions resulted in significantly higher anterior tibial translation (position 1: 13.8 +/- 4.6 mm; position 2: 16.6 +/- 3.7 mm; P < .05). There was a significant difference between the 2 tunnel positions. At the same flexion angle, the anterior tibial translation in response to the combined load for the intact knee was 7.7 +/- 4.0 mm. Both femoral tunnel positions resulted in significantly higher anterior tibial translation (position 1: 10.4 +/- 5.5 mm; position 2: 12.0 +/- 5.2 mm; P < .05), with a significant difference between the tunnel positions. CONCLUSION: Neither femoral tunnel position restores normal kinematics of the intact knee. A femoral tunnel position inside the anatomical footprint of the anterior cruciate ligament results in knee kinematics closer to the intact knee than does a tunnel position located for best graft isometry. CLINICAL RELEVANCE: Anatomical femoral tunnel position is important in reproducing function of the anterior cruciate ligament.

Internal impingement: findings on magnetic resonance imaging and arthroscopic evaluation.

PURPOSE: The purpose of this study was to examine preoperative shoulder magnetic resonance imaging (MRI) and intraoperative arthroscopic findings in throwing athletes with a clinical diagnosis of internal impingement. TYPE OF STUDY: Retrospective review. METHODS: A retrospective review of the surgical indications for 769 shoulder arthroscopic procedures performed from 1997 to 2000 revealed 9 throwing athletes with a diagnosis of severe internal impingement. Each had failed treatment that included a minimum of 3 months of rehabilitation. Preoperative MRIs in all 9 were read by a fellowship-trained musculoskeletal radiologist blinded to the operative findings. Findings at arthroscopy were culled from the operative reports. RESULTS: On both MRI and at arthroscopy, all 9 athletes had posterosuperior labral lesions, 1 had a humeral head articular cartilage lesion, and 1 had a SLAP lesion. Additional findings on MRI included humeral head edema, subchondral cystic changes, posterosuperior glenoid sclerosis, and rotator cuff tendonopathy predominantly in the infraspinatus. At arthroscopy, there were additional findings of articular-sided partial rotator cuff tears not shown on MRI. CONCLUSIONS: Both MRI and arthroscopic findings described labral and humeral head articular cartilage lesions. These findings may be indicative of internal impingement in throwing athletes. LEVEL OF EVIDENCE: Level III, diagnostic.

Glenohumeral translations are increased after a type II superior labrum anterior-posterior lesion: a cadaveric study of severity of passive stabilizer injury.

The effects of simulated type II superior labrum anterior-posterior (SLAP) lesions were studied to determine whether the severity of the lesion affected glenohumeral joint translations. A robotic/universal force-moment sensor testing system was used to simulate load-and-shift tests by applying an anterior or posterior load of 50 N to each shoulder. The apprehension test for anterior instability was simulated by applying an anterior load of 50 N with an external rotation torque of 3 Nm at 30 degrees and 60 degrees of abduction. This loading protocol was repeated after creating two type II SLAP lesions of different severity. In the first the superior labrum and the biceps anchor were elevated subperiosteally from the glenoid bone (SLAP-II-1), and in the second the biceps anchor was completely detached (SLAP-II-2). Statistical analysis was performed with a 2-factor repeated-measures analysis of variance followed by multiple contrasts, and the significance level was set at P <.05. At 30 degrees of abduction, anterior translation of the vented joint from anterior loading was 18.5 +/- 8.5 mm. It was significantly increased (26.2 +/- 6.5 mm, P =.03), after the SLAP-II-2 lesion and compared with the SLAP-II-1 lesion (25.0 +/- 6.8 mm, P =.03). Increases in anterior translations at 60 degrees of abduction were not significantly differ in comparison to the two SLAP lesions. Inferior translation also resulted from anterior loading. At 30 degrees of abduction in the vented joint, it was 3.8 +/- 4.0 mm and was significantly increased (8.5 +/- 5.4 mm, P =.05) after the SLAP-II-2 lesion, no different than that after the SLAP-II-1 lesion (7.8 +/- 4.9 mm). No significant increases in anterior translation occurred in response to the combined loading condition between the two SLAP lesions. Glenohumeral translation was increased, regardless of severity, after simulation of type II SLAP lesions. During stabilizing surgical interventions, passive stabilizers that are injured in the type II SLAP lesion should be considered as well as dynamic activity in the tendon of the long head of the biceps brachii.