Journal of Shoulder and Elbow Surgery最新文献

Background: Scapular dyskinesis is frequently observed with various types of shoulder instability, but whether scapular dyskinesis could contribute to shoulder instability is still unclear. The purpose of this study was to determine the effects of scapular orientation on anterior and posterior glenohumeral translation using a cadaveric model of anterior and posterior labral tears.

Methods: Twenty fresh-frozen cadaveric shoulders were divided into two groups: the anterior lesion (n=10) and posterior lesion (n=10) groups. The humeral head was translated anteriorly or posteriorly with a constant 30 N force in the anterior or posterior tear groups, respectively. Humeral head displacement was measured at neutral scapula orientation for the intact labrum and following anterior or posterior labral tears. Following a labral tear, humeral head displacement was also measured at six additional scapular orientations (±10° increments from neutral), including downward rotation, upward rotation, posterior tilt, anterior tilt, internal rotation, and external rotation. The humerus was held at 0° of horizontal abduction and 40° of horizontal abduction (the apprehension test position) or 40° of horizontal adduction (the jerk test position) in the anterior lesion or posterior lesion groups, respectively.

Results: The presence of isolated labral tears generally increased anterior and posterior translations on the order of 1-2 mm in the neutral scapular orientation (P≤0.021). Anterior humeral head translation in 0° humeral abduction further increased by approximately 1 mm in the mean upward scapular rotation orientation (P≤0.021). In the apprehension test, anterior translation increased from posterior to anterior scapular tilt (1.3 mm, P=0.017), and from internal to external scapular rotation (1.8 mm, P≤0.006). Posterior humeral translation in 0° humeral abduction showed trends increasing from downward to upward scapular rotation (1.2 mm, P≤0.027) and posterior to anterior scapular tilt (2.8 mm, P≤0.007), while slightly decreasing from internal to external scapular rotation (0.6 mm, P=0.014). Posterior translation in the jerk test increased from downward to upward scapular rotation (0.8 mm, P≤0.012) and posterior to anterior scapular tilt (0.9 mm, P≤0.043), but slightly decreased from internal to external scapular rotation (0.6 mm, P=0.001).

Conclusion: Increased scapular upward rotation, anterior tilt, and external rotation were associated with increased anterior translation of the humeral head in shoulders with anterior labral lesions. In shoulders with posterior labral lesions, increased scapular upward rotation, anterior tilt, and internal rotation were associated with increased posterior translation of the humeral head. These findings suggest that scapular dyskinesis could contribute to instability recurrence.

Background: Frailty is a well-established predictor of poor outcomes after orthopaedic surgery. The 6-item Modified Frailty Index (mFI-6), which includes hypoalbuminemia, may provide enhanced risk stratification compared to the widely used 5-item Modified Frailty Index (mFI-5). The predictive value of the mFI-6 versus the mFI-5 for short-term complications after surgical management of proximal humerus fractures (PHFs) remains unclear.

Methods: A retrospective analysis of the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was conducted to identify patients who underwent open reduction and internal fixation, hemiarthroplasty, or total shoulder arthroplasty for PHFs from 2011 to 2023. Patients were stratified by mFI-6 score (< 3 vs. ≥ 3). Thirty-day outcomes, including readmission, mortality, complications, hospital length of stay, and discharge disposition, were measured. Receiver operating characteristic (ROC) analysis compared the predictive performance of the mFI-6 and mFI-5 for these outcomes.

Results: A total of 30,070 patients met inclusion criteria. 5.4% were classified as highly frail (mFI-6 ≥ 3). Patients with high mFI-6 scores had significantly increased rates of readmission (9.9% vs. 2.9%), mortality (1.6% vs. 0.2%), overall complications (15.2% vs. 4.7%), non-home discharge (29.1% vs 8.6%), and longer hospital stays (4 ± 5 days vs. 2 ± 4 days) (all P-values < 0.001). After multivariate regression, these outcomes remained independently associated with high mFI-6 scores. The area under the ROC curve for the mFI-6 was highest for mortality (AUC 0.751), showing consistently superior performance compared to the mFI-5 for readmission, mortality, complications, and non-home discharge. After stratifying by procedure, such differences remained across most outcomes.

Discussion: In patients undergoing operative management of PHFs, higher mFI-6 scores are strongly associated with adverse 30-day outcomes. The mFI-6 demonstrates improved predictive ability over the mFI-5, supporting its adoption for preoperative risk stratification in patients undergoing surgery for PHFs.

Background: Lesser tuberosity osteotomy (LTO) repair in total stemless shoulder arthroplasty has a high nonunion rate and thus presents a challenge to shoulder surgeons. Improved repair techniques may mitigate nonunion from excessive fragment motion or inadequate compression. The purpose of this study was to evaluate the biomechanical properties of three LTO repair techniques in the setting of stemless shoulder arthroplasty. Tensionable cortical button (Button) and suture anchor (Anchor) constructs were compared to a reference suture with a lateral plate construct (Suture).

Methods: Forty human cadaveric shoulders from twenty matched pairs were dissected and the lesser tuberosity osteotomized. In each pair, the LTO was repaired with a Suture and lateral plate construct on one side and on the other side, either a tensionable cortical Button or suture Anchor construct was used. Sutures were passed through the humeral components of a stemless arthroplasty system during the procedures. All specimens were cycled 1000 times from 10-100 N at 1 Hz using a custom subscapularis cryoclamp. Cyclic construct gapping was recorded at regular intervals with a digital video system. All specimens were then loaded to failure, and failure load, displacement, mode, and construct stiffness were recorded. Statistical analyses compared the Suture constructs to their paired Button or Anchor constructs.

Results: Compared to their Suture pairs, the Button group displayed no differences in construct gapping (p≥0.138), but the Anchor group displayed up to 50% increased gapping from cycles 1-400 (p≤0.049). The Suture construct supported approximately 25% higher loads prior to failure when compared to their paired Button and Anchor group (p≤0.014). There were no differences in failure stiffness between the Sutures and their paired Buttons or Anchors.

Conclusion: In this controlled laboratory study, the decreased rate of initial construct gap formation and greater failure load of the suture construct suggests an environment for superior in vivo healing of the LTO as a result of decreased micromotion, with clinical implications still to be determined. Furthermore, the greater failure load in the suture construct could prevent catastrophic failure of the LTO in the delicate post-operative period. In the setting of total shoulder arthroplasty, an LTO subscapularis repair utilizing a suture with a lateral plate construct provides a biomechanically superior repair to either a tensionable cortical button or suture anchor repair.

Background: The advent of modern, precontoured locking plates has improved treatment of distal humerus fractures (DHFs) by providing an anatomic fit and a reliable locking mechanism with interdigitating screws. However, severe articular comminution may predispose surgical failure despite anatomic reduction and a biomechanically strong construct.

Methods: A retrospective review was performed to identify patients who underwent distal humerus open reduction internal fixation (ORIF) between 2015 and 2020. Fractures were classified using the AO/OTA classification and further categorized by anatomic location and number of fragments on preoperative imaging. Articular comminution was defined as the number of articular fracture fragments ≥1.5cm and stratified as high (>= 5 fragments) and low (<5 fragments) comminution. Outcomes included elbow range of motion, quick Disabilities of the Arm, Shoulder, and Hand (qDASH), and Mayo Elbow Performance Score (MEPS). Complications were classified as major or minor based on the need for reconstructive reoperation. Outcomes and complications between high and low comminution DHFs were compared using Student's t-test and Fisher's exact test.

Results: The study cohort consisted of 51 patients, 38 female (75%) and 13 male (25%), with an average age of 63.3 years. Fracture types included 9 AO/OTA type A, 7 type B, and 35 type C. At a mean follow-up of 47 months, the mean arc of motion in the high comminution group was 104° versus 109° in the low comminution group (p=0.595). The mean MEPS was 79 versus 88 (p=0.376) and mean qDASH score was 29 versus 19 (p=0.219) in the high comminution and low comminution groups respectively. Among the intra-articular fractures, patients with high comminution fractures experienced significantly more major complications (87.5% vs. 16.3%, p<0.001) and overall complications (87.5% versus 30.2%, p=0.001) compared with those in the low comminution group. Major complications in the high comminution group included bone resorption with conversion to arthroplasty and radical contracture releases with heterotopic ossification excision. Major complications in the low comminution group included nonunion, elbow contractures, deep infection, and bone resorption with implant failure. All highly comminuted fractures achieved satisfactory reduction with parallel plate fixation. Final qDASH and MEPS scores were not affected by comminution severity, although a significantly higher proportion of patients required revision surgery in the high comminution group.

Conclusion: Precontoured locking plates provide reliable fixation for intra-articular DHFs. However, severe articular comminution is associated with complications resulting in major reconstructive reoperations, even with satisfactory fixation. Despite this, conversion to total elbow arthroplasty remains low.

Background: Fatty infiltration (FI) and muscle atrophy following rotator cuff (RC) tears are largely irreversible and are major determinants of poor surgical outcomes, increased re-tear risk, and long-term functional disability. No pharmacologic therapies have been validated to prevent or reverse these degenerative changes. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), including liraglutide, have demonstrated anti-adipogenic and tissue-preserving effects in other organ systems, suggesting potential application in RC-related muscle degeneration.

Purpose: To evaluate the effects of systemic liraglutide administration on FI, muscle morphology, and functional outcomes in a rat model of chronic RC tear without tendon repair.

Study design: Controlled laboratory study.

Methods: Adult male Sprague-Dawley rats underwent unilateral supraspinatus tendon transection with interposition of a silicone tube to prevent tendon-to-bone healing. Animals were randomly assigned to receive subcutaneous liraglutide (250 ㎍/kg/day) or saline for 4 weeks, starting 2 weeks post-injury. At 6 weeks post-surgery, FI was assessed using Oil Red O staining, muscle morphology was examined via hematoxylin-eosin histology, and passive shoulder range of motion (ROM) was measured with a goniometer. Neuromuscular function was evaluated through compound muscle action potential (CMAP) recordings, and FI was quantified as the percentage of red-stained FI area using ImageJ software with a uniform color-threshold algorithm.

Results: GLP-1RA significantly reduced FI compared with controls (Oil Red O-positive area: 1.11 ± 0.75% vs 11.82 ± 3.89%, p < .001) and markedly decreased adipocyte deposition on H&E staining. Passive internal rotation was preserved (79 ± 38° vs 70 ± 2°, p < .001), as was external rotation (55 ± 2° vs 48 ± 3°, p < .001). CMAP amplitudes were significantly greater in the liraglutide group (19.43 ± 8.77 mV vs 7.61 ± 3.15 mV, p = .028).

Conclusion: Systemic liraglutide administration attenuated chronic muscle degeneration after RC tear by limiting FI, preserving muscle fiber morphology, maintaining joint mobility, and supporting neuromuscular function. These findings provide preclinical justification for therapeutic repositioning of GLP-1RAs in musculoskeletal disorders characterized by irreversible fatty degeneration.

Background: Hand-behind-back (HBB) motion is commonly used to assess shoulder internal rotation; however, it involves multiple joint movements, including scapulothoracic, glenohumeral, and elbow joint motions, thus complicating the interpretation of the HBB position. This study aimed to investigate three-dimensional joint alignment during HBB motion of the bilateral shoulders in patients with frozen shoulder and to identify which joint motions primarily contribute to motion limitation.

Methods: Seventeen patients with unilateral frozen shoulder underwent bilateral shoulder computed tomography (CT) scans in the neutral and HBB positions using an upright multidetector CT. Bone surface models of the thorax, scapula, humerus, and forearm were created to calculate the rotation of the scapulothoracic, glenohumeral, thoracohumeral, and elbow joints. The affected and unaffected sides were compared, and the correlation between the HBB reach level (vertebral level) and the thoracohumeral internal rotation angle was analyzed.

Results: No significant differences in joint rotation were observed between the sides in the neutral position. The affected side demonstrated significantly reduced glenohumeral internal rotation (31° vs. 66°, P < 0.001), abduction (10° vs. 22°, P < 0.001), and elbow flexion (74° vs. 115°, P < 0.001) during HBB motion. The scapulothoracic joint on the affected side had less internal rotation (18° vs. 21°; P = 0.045) and more anterior tilt (24° vs. 19°; P = 0.003). The HBB reach level was negatively correlated with the thoracohumeral internal rotation angle in the unaffected and affected sides (r = -0.518 and r = -0.675, respectively).

Conclusion: This study clarified that limited internal rotation of the glenohumeral joint is the main cause of restricted HBB motion in frozen shoulder, which supports the use of the thumb-to-spinous process as a valid measure of thoracohumeral internal rotation in patients with frozen shoulder.