Reconstruction of the Acromioclavicular Ligament Complex Using Dermal Allograft: A Biomechanical Analysis.

PURPOSE: To analyze the posterior translational and rotational stability of the acromioclavicular (AC) joint following reconstruction of the superior acromioclavicular ligament complex (ACLC) using dermal allograft. METHODS: Six fresh-frozen cadaveric shoulders were used (mean age of 65.3 ± 6.9 years). The resistance force against posterior translation (10 mm) and torque against posterior rotation (20°) was measured. Specimens were first tested with both the intact ACLC and coracoclavicular ligaments. The ACLC and coracoclavicular ligaments were then transected so simulate a Type III/V AC joint dislocation. Each specimen then underwent 3 testing conditions, performed in the following order: (1) ACLC patch reconstruction alone, (2) ACLC patch with an anatomic coracoclavicular reconstruction (ACCR) using semitendinosus allograft, and (3) the transected ACLC with an ACCR only. Differences in posterior translational and rotational torque across testing conditions were analyzed with a one-way repeated analysis of variance analysis. RESULTS: Mean resistance against posterior translation in the intact condition was 65.76 ± 23.8 N. No significant difference found between the intact condition compared with specimens with the ACLC-patch only (44.2 ± 11.3 N, P = .06). The ACCR technique, when tested alone, had significantly less posterior translational resistance compared with the intact condition (38.5 ± 8.94 N, P = .008). ACLC patch in combination with an ACCR was closest in restoring native posterior translation (57.1 ± 19.2 N, P = .75). For rotational resistance, only the addition of the ACLC patch with an ACCR (0.51 ± 0.07 N-m) demonstrated similar torque compared with the intact joint (0.89 ± 0.5 N-m, P = .06). CONCLUSIONS: The ACLC-patch plus ACCR technique was able to closest restore the percent of normal posterior translational and rotational stability. CLINICAL RELEVANCE: Recurrent posterior instability of the AC joint is a potential complication after coracoclavicular reconstruction surgery. In the in vitro setting, this study demonstrated increased AC joint stability with the addition of an ACLC reconstruction using dermal allograft.

Biomechanical Effect of Superior Capsule Reconstruction Using a 3-mm and 6-mm Thick Acellular Dermal Allograft in a Dynamic Shoulder Model.

PURPOSE: To biomechanically compare the effect of superior capsule reconstruction (SCR) using a 3- and 6-mm thick acellular dermal allograft for the treatment of irreparable rotator cuff tears. METHODS: Eight fresh-frozen cadaveric shoulders were tested using a dynamic shoulder model. Maximum abduction angle (MAA), glenohumeral superior translation (ghST), subacromial peak contact pressure (sPCP), and cumulative deltoid force (cDF) were compared among 4 conditions: (1) intact shoulder, (2) simulated irreparable rotator cuff tear (RCT), (3) SCR using a 3-mm-thick acellular dermal allograft, (4) SCR using a 6-mm-thick acellular dermal allograft. RESULTS: Compared with the intact state, simulated irreparable RCTs significantly decreased MAA (P < .001), while significantly increasing ghST (P = .001), sPCP (P < .001), and cDF (P < .001). SCR with a 3-mm-thick graft significantly increased MAA (P = .01) and decreased ghST (P = .01) compared with the RCT state, however, showed similar sPCP and cDF. Compared with the torn state, SCR with a 6-mm-thick graft significantly increased MAA (P < .001) and significantly decreased ghST (P < .001), sPCP (P < .001), and cDF (P = .001). Using a 6-mm-thick graft demonstrated similar MAA, ghST, sPCP, and cDF compared with the intact state. When comparing the 3-mm to the 6-mm thick graft, significant differences were found in ghST (P = .03), sPCP (P < .001), and cDF (P = .02). CONCLUSIONS: SCR with a 6-mm-thick acellular dermal allograft better restored normal glenohumeral joint position and forces compared with a 3-mm-thick graft for the treatment of irreparable RCTs. CLINICAL RELEVANCE: Graft thickness may affect the clinical success following SCR with commercially available dermal allografts. Using a thicker (>3 mm) graft was able to biomechanically better restore native glenohumeral joint properties.

Examining the Potency of Subacromial Bursal Cells as a Potential Augmentation for Rotator Cuff Healing: An In Vitro Study.

PURPOSE: To compare the potency of mesenchymal stem cells between the cells derived from the subacromial bursa to concentrated bone marrow aspirate (cBMA) taken from patients undergoing rotator cuff (RC) repair. METHODS: Subacromial bursa and cBMA were harvested arthroscopically from 13 patients (age 57.4 ± 5.2 years, mean ± standard deviation) undergoing arthroscopic primary RC repair. Bone marrow was aspirated from the proximal humerus and concentrated using an automated system (Angel System; Arthrex). Subacromial bursa was collected from 2 sites (over the RC tendon and muscle) and digested with collagenase to isolate a single cellular fraction. Proliferation, number of colony-forming units, differentiation potential, and gene expression were compared among the cells derived from each specimen. RESULTS: The cells derived from subacromial bursa showed significantly higher proliferation compared with the cells derived from cBMA after 5, 7, and 10 days (P = .018). Regarding colony-forming units, the subacromial bursa had significantly more colonies than cBMA (P = .002). Subacromial bursal cells over the RC tendon produced significantly more colonies than cells over both the RC muscle and cBMA (P = .033 and P = .028, respectively). Moreover, when compared with cBMA, cells derived from subacromial bursa showed significantly higher differentiation ability and higher gene expression indicative of chondrogenesis, osteogenesis, and adipogenesis. CONCLUSION: The subacromial bursa is an easily accessible tissue that can be obtained during RC repair, with significant pluripotent stem cell potency for tendon healing. Compared with cBMA taken from the proximal humerus, bursal cells showed significantly increased differentiation ability and gene expression over time. CLINICAL RELEVANCE: Failed RC repairs have been partly attributed to a poor healing environment. Biologic augmentation of the repair site may help increase healing potential and incorporation of the cuff at the tendon-bone interface.

Repair of the entire superior acromioclavicular ligament complex best restores posterior translation and rotational stability.

PURPOSE: The acromioclavicular ligament complex (ACLC) is the primary stabilizer against horizontal translation with the superior ACLC providing the main contribution. The purpose of this study was to evaluate the specific regional contributions in the superior half of ACLC, where the surgeon can easily access and repair or reconstruct, for posterior translational and rotational stability. METHODS: The superior half of ACLC was divided into three regions; Region A (0°-60°): an anterior 1/3 region of the superior half of ACLC, Region B (60°-120°): a superior 1/3 region of the superior half of ACLC, and Region C (120°-180°): a posterior 1/3 region of the superior half of ACLC. Fifteen fresh-frozen cadaveric shoulders were used. Biomechanical testing was performed to evaluate the resistance force against passive posterior translation (10 mm) and the resistance torque against passive posterior rotation (20°) during the following the four conditions. (1) Stability was tested on all specimens in their intact condition (n = 15). (2) The ACLC was dissected and stability was tested (n = 15). (3) Specimens were randomly divided into three groups by regions of suturing. Stability was tested after suturing Region A, Region B, or Region C (n = 5 per group). (4) Stability was tested after suturing additional regions: Region A + B (0°-120°), Region B + C (60°-180°), or Region A + C (0°-60°, 120°-180°, n = 5 per group). RESULTS: The translational force increased after suturing Region A when compared with dissected ACLC (P = 0.025). The force after suturing Region A + B was significantly higher compared to the dissected ACLC (P < 0.001). The rotational torque increased after suturing Region A or Region B compared with dissected ACLC (P = 0.020, P = 0.045, respectively). The torque after suturing the Region A + C was significantly higher compared to the dissected ACLC (P < 0.001). CONCLUSION: The combined Region A + B contributed more to posterior translational stability than Region B + C or Region A + C. In contrast, combined Region A + C contributed more to posterior rotational stability than Region A + B or Region B + C. Based on these findings, surgical techniques restoring the entire superior ACLC are recommended to address both posterior translational and rotational stability of the AC joint.

Higher Critical Shoulder Angle and Acromion Index Are Associated With Increased Retear Risk After Isolated Supraspinatus Tendon Repair at Short-Term Follow Up.

PURPOSE: To evaluate the effect of critical shoulder angle (CSA), acromion index (AI), and glenoid inclination (GI) on the postoperative healing rate after arthroscopic supraspinatus tendon repair. METHODS: Patients after arthroscopic repair of a symptomatic, unilateral, single-tendon, full-thickness supraspinatus tear in whom nonoperative management had failed were retrospectively reviewed. Magnetic resonance imaging (MRI) studies were obtained 6 months postoperatively and were evaluated by 2 independent observers. Repair integrity was classified as either intact or torn. Preoperative true anteroposterior radiographs were used to measure CSA, AI, and GI. RESULTS: Fifty-seven patients were evaluated 6 months postoperatively. The mean patient age at surgery was 54.7 ± 7.7 years. On MRI studies, 41 patients (71.9%) had an intact repair and 16 patients (28.1%) had a full-thickness retear. There were no significant differences between the intact and retear group in regard to patient age (P = .648), initial tear size (P = .205), or fatty degeneration (P = .508). The mean CSA for the retear group (37° ± 4°) was significantly higher than that in the intact group (35° ± 3°; P = .014). If the CSA was >38°, the odds ratio of having a retear was 3.78 (95% confidence interval 1.05 to 13.58; P = .042). Average AI for the retear group (0.73 ± 0.09) was significantly higher than that in the intact group (0.69 ± 0.06; P = .049). The mean GI was 17° ± 6° for the intact group and 16° ± 6° for the retear group (P = .739). CONCLUSIONS: At short-term follow-up, higher CSA and AI significantly increased the retear risk after arthroscopic supraspinatus tendon repair. CSA >38° increased the retear risk almost 4-fold. Overall GI was elevated but did not correlate with failure rate. LEVEL OF EVIDENCE: III, case control study.

Serum and Wound Vancomycin Levels After Intrawound Administration in Primary Total Joint Arthroplasty.

BACKGROUND: Periprosthetic joint infection is the most common cause of readmissions after total joint arthroplasty (TJA). Intrawound vancomycin powder (VP) has reduced infection rates in spine surgery; however, there are no data regarding VP in primary TJA. METHODS: Thirty-four TJA patients received 2 g of VP intraoperatively to investigate VP's pharmacokinetics. Serum and wound concentrations were measured at multiple intervals over 24 hours after closure. RESULTS: All serum concentrations were subtherapeutic (<15µg/mL) and peaked 12 hours after closure (4.7µg/mL; standard deviation [SD], 3.2). Wound concentrations were 922 µg/mL (SD, 523) 3 hours after closure and 207 µg/mL (SD, 317) at 24 hours. VP had a half-life of 7.2 hours (95% confidence interval, 7.0-9.3) in TJA wounds. CONCLUSIONS: VP produced highly therapeutic intrawound concentrations while yielding low systemic levels in TJA. VP may serve as a safe adjunct in the prevention of periprosthetic joint infection.

Contour subregion error detection methodology using deep learning auto-segmentation.

BACKGROUND: Inaccurate manual organ delineation is one of the high-risk failure modes in radiation treatment. Numerous automated contour quality assurance (QA) systems have been developed to assess contour acceptability; however, manual inspection of flagged cases is a time-consuming and challenging process, and can lead to users overlooking the exact error location. PURPOSE: Our aim is to develop and validate a contour QA system that can effectively detect and visualize subregional contour errors, both qualitatively and quantitatively. METHODS/MATERIALS: A novel contour subregion error detection (CSED) system was developed using subregional surface distance discrepancies between manual and deep learning auto-segmentation (DLAS) contours. A validation study was conducted using a head and neck public dataset containing 339 cases and evaluated according to knowledge-based pass criteria derived from a clinical training dataset of 60 cases. A blind qualitative evaluation was conducted, comparing the results from the CSED system with manual labels. Subsequently, the CSED-flagged cases were re-examined by a radiation oncologist. RESULTS: The CSED system could visualize the diverse types of subregional contour errors qualitatively and quantitatively. In the validation dataset, the CSED system resulted in true positive rates (TPR) of 0.814, 0.800, and 0.771; false positive rates (FPR) of 0.310, 0.267, and 0.298; and accuracies of 0.735, 0.759, and 0.730, for brainstem and left and right parotid contours, respectively. The CSED-assisted manual review caught 13 brainstem, 19 left parotid, and 21 right parotid contour errors missed by conventional human review. The TPR/FPR/accuracy of the CSED-assisted manual review improved to 0.836/0.253/0.784, 0.831/0.171/0.830, and 0.808/0.193/0.807 for each structure, respectively. Further, the time savings achieved through CSED-assisted review improved by 75%, with the time for review taking 24.81 ± 12.84, 26.75 ± 10.41, and 28.71 ± 13.72 s for each structure, respectively. CONCLUSIONS: The CSED system enables qualitative and quantitative detection, localization, and visualization of manual segmentation subregional errors utilizing DLAS contours as references. The use of this system has been shown to help reduce the risk of high-risk failure modes resulting from inaccurate organ segmentation.

Analysis of Patient Factors Affecting In Vitro Characteristics of Subacromial Bursal Connective Tissue Progenitor Cells during Rotator Cuff Repair.

Unsatisfactory failure rates following rotator cuff (RC) repair have led orthopaedic surgeons to explore biological augmentation of the healing enthesis. The subacromial bursa (SB) contains abundant connective tissue progenitor cells (CTPs) that may aid in this process. The purpose of the study was to investigate the influence of patient demographics and tear characteristics on the number of colony-forming units (CFUs) and nucleated cell count (NCC) of SB-derived CTPs. In this study, we harvested SB tissue over the supraspinatus tendon and muscle in 19 patients during arthroscopic RC repair. NCC of each sample was analyzed on the day of the procedure. After 14 days, CFUs were evaluated under a microscope. Spearman's rank correlation coefficient was then used to determine the relationship between CFUs or NCC and patient demographics or tear characteristics. The study found no significant correlation between patient demographics and the number of CFUs or NCC of CTPs derived from the SB (p > 0.05). The study did significantly observe that increased tear size was negatively correlated with the number of CFUs (p < 0.05). These results indicated that increased tear size, but not patient demographics, may influence the viability of CTPs and should be considered when augmenting RCrepairs with SB.

Assessment of Basic Ankle Arthroscopy Skills in Orthopedic Trainees.

BACKGROUND: There is increasing emphasis on assessing resident competency, but little has been published on how to best evaluate trainee competency for ankle arthroscopy. The purpose of this study was to validate an objective model for assessing basic ankle arthroscopy knowledge and operative skills on a cadaveric ankle. METHODS: The Diagnostic Ankle Arthroscopy Skills Scoring System was adapted from previously validated assessment tools for knee arthroscopy. The scoring system included (1) an oral questionnaire (0-23 points), (2) an operative task-specific checklist (0-19 points), and (3) a global operative skills rating (12-60 points). Thirty-three trainees consisting of orthopedic residents and medical students performed a diagnostic ankle arthroscopy on a cadaveric ankle and were assessed by a single observer, while a subset were tested by 2 evaluators to determine interobserver reliability. RESULTS: There was strong correlation between educational level and scores on the global operative skills rating scale (r = 0.967, P < .0001), task-specific checklist (r = 0.815, P < .815), and oral questionnaire (r = 0.896, P < .0001). The global operative skills scores significantly improved with training level, and the largest difference was between medical students and senior residents. The most notable year-to-year increases in skill were between postgraduate year (PGY) 1 and 2 (P < .01) and between PGY2 and PGY3 (P < .05). Oral questionnaire and task-specific checklists were significantly lower for medical students than PGY1 residents (P < .001). There was also significant improvement in the oral questionnaire between senior and junior residents (P < .05). There was a moderate correlation between number of self-reported ankle arthroscopy cases and scores on the global operative skills score (r = 0.7019, P < .0001). Interobserver reliability was high for the global operative skills scores (interclass correlation coefficient = 0.89). CONCLUSION: The study revealed a valid measure to objectively assess trainees' ankle arthroscopy clinical knowledge and operative skills in a bioskills laboratory. CLINICAL RELEVANCE: This tool should enable residency programs to evaluate competency and track individual trainee progress over time.

Utility of pre-procedural CT and abdominal radiography before percutaneous radiologic gastrostomy placement.

PURPOSE: To evaluate the utility of pre-procedural CT and abdominal radiography before percutaneous radiologic gastrostomy tube placement. METHODS: A retrospective review of gastrostomy tube placements was conducted at a tertiary care radiology department. During the studied period, all percutaneous radiologic G-tube placements (PRG) at the institution required a pre-procedural abdominal CT. Whether the CT was interpreted to have an adequate window for PRG was recorded. The same patients with pre-procedural abdominal radiographs were also identified and retrospectively reviewed for the presence of satisfactory anatomy for PRG. Outcomes of tube placements were reviewed. RESULTS: 126 PRG requests were identified, all with abdominal CTs. 110 also had an abdominal radiograph. An adequate window for PRG was present in 83% of patients by CT and 73% by radiography. Of patients in whom it was attempted, 94% underwent successful PRG with a 7.4% minor complication rate. Of those refused for PRG based on CT, 9% had successful percutaneous endoscopic G-tube placement, resulting in a sensitivity of 98%. 97% of patients with satisfactory anatomy by radiograph underwent successful PRG. Of those with no window, 66% had a window by CT, and 94% in whom it was attempted had successful PRG placement. This resulted in a sensitivity of 77% for radiography. Concordance between CT and radiography was 73%. CONCLUSIONS: Pre-procedural CT interpretation is highly predictive of successful and uncomplicated PRG. Abdominal radiography also predicts successful PRG, but with a lower accuracy, limiting its utility as a pre-procedural exam.

Biomechanical Comparison of Anterograde and Retrograde Lesser Trochanter Avulsion Repair.

BACKGROUND: Lesser trochanter avulsions are rare injuries in adolescents. Severe cases with relevant fragment displacement can be treated surgically. However, no standard approach is available in the literature. Operative techniques are presently limited to anterograde fixations. A new retrograde approach to reduce operative difficulty and postoperative morbidity has been proposed. So far, no biomechanical comparison of these techniques is available. HYPOTHESIS: Retrograde repair of the lesser trochanter with a titanium cortical button will produce superior stability under load to failure and similar displacement under cyclic loading compared with anterograde fixation with titanium suture anchors. STUDY DESIGN: Controlled laboratory study. METHODS: Sixteen paired hemipelvic cadaveric specimens (mean age, 62.5 ± 10.7 years) were dissected to isolate the lesser trochanter and iliopsoas muscle. After repair of a simulated lesser trochanter avulsion, specimens were tested under cyclic loading between 10 and 125 N at 1 Hz for 1500 cycles before finally being loaded to failure at a rate of 120 mm/min in a material testing machine. Motion tracking was used to assess displacement at the superior and inferior aspects of the iliopsoas tendon under cyclic loading. RESULTS: Load to failure was significantly greater for the retrograde repair compared with the anterograde repair (1075.24 ± 179.39 vs 321.85 ± 62.45 N; P = .012). Mean displacement at the superior repair aspect (retrograde vs anterograde: 3.29 ± 1.84 vs 4.39 ± 4.50 mm; P = .779) and mean displacement at the inferior aspect (3.54 ± 2.13 vs 4.22 ± 4.48 mm; P = .779) of the iliopsoas tendon did not significantly differ by the type of repair. Mode of failure was tendon tearing by the sutures for each retrograde repair and anchor pullout for each anterograde repair. CONCLUSION: Surgical repair of lesser trochanter avulsion fractures with retrograde fixation using a titanium cortical button demonstrated superior load to failure and similar displacement under cyclic loading compared with anterograde fixation using suture anchors. CLINICAL RELEVANCE: The retrograde approach provides a biomechanically validated alternative to other surgical techniques for this injury.

Flexor Hallucis Longus Transfer Improves Achilles Tendon Load to Failure in Surgery for Non-Insertional Tendinopathy: A Biomechanical Study.

BACKGROUND: Non-insertional Achilles tendinopathy is a common disorder that may be treated with surgical debridement. A flexor hallucis longus (FHL) transfer is recommended if debridement of ≥50% is performed; however, there are no biomechanical data to support this. The purpose of this study was to assess the added biomechanical strength provided by an FHL transfer with incrementally sized non-insertional Achilles tendon defects. METHODS: Thirty matched-pair below-the-knee cadaveric specimens (n = 60) (mean age at the time of donor death, 67 years; range, 36 to 74 years) were obtained and randomly divided into 3 groups according to whether the defect was 25%, 50%, or 75% of the tendon width. One specimen of each pair was then randomly selected to undergo FHL transfer using interference screw fixation. All specimens then underwent cyclic loading of 100 N, and elongation of the medial and lateral limbs of the tendon defect was recorded. The constructs were then loaded to failure to measure stiffness, ultimate strength, and peak elongation before failure. RESULTS: The specimens with a 75% defect had significantly less elongation of the medial and lateral tendon-defect limbs when an FHL transfer had been done (p < 0.05). Ultimate load to failure was significantly increased in all groups (by 242 to 270 N depending on the defect size) following FHL transfer. Failures usually occurred through the tendon defect in the 75% and 50% defect groups, whereas all failures occurred at the Achilles tendon insertion when a 25% defect had been created. No significant differences were found in peak elongation with the addition of an FHL transfer. FHL augmentation resulted in significantly greater stiffness in the 25% and 75% defect groups (p < 0.05). CONCLUSIONS: This study showed that an FHL transfer significantly increased load to failure of Achilles tendons with a non-insertional defect involving 25%, 50%, and 75% of the tendon width. The mechanism of failure was usually through the defect in the specimens with a 50% or 75% defect, supporting the use of FHL augmentation with debridement of ≥50%. CLINICAL RELEVANCE: The present study supports the mechanical concept that FHL transfer is indicated when debridement of the Achilles tendon is ≥50%.

Shoulder Acromioclavicular and Coracoclavicular Ligament Injuries: Common Problems and Solutions.

Injuries to the acromioclavicular joint and coracoclavicular ligaments are common. Many of these injuries heal with nonoperative management. However, more severe injuries may lead to continued pain and shoulder dysfunction. In these patients, surgical techniques have been described to reconstruct the function of the coracoclavicular ligaments to provide stable relationship between the clavicle and scapula. These surgeries have been fraught with high complication rates including clavicle and coracoid fractures, infection, loss of reduction and fixation, hardware migration, and osteolysis. This article reviews common acromioclavicular and coracoclavicular repair and reconstruction techniques and associated complications, and provides recommendations for prevention and management.