Human Motor Endplate Survival after Chronic Peripheral Nerve Injury.

Objective: Degeneration of motor endplates (MEPs) in denervated muscle is thought to be a key factor limiting functional regeneration after peripheral nerve injury (PNI) in humans. However, there is currently no paradigm to determine MEP status in denervated human muscle to estimate likelihood of reinnervation success. Here, we present a quantitative analysis of MEP status in biopsies of denervated muscles taken during nerve repair surgery and ensuing functional recovery. Methods: This is a retrospective single-surgeon cohort study of patients (n=22) with upper extremity PNI confirmed with electromyography (EMG), treated with nerve transfers. Muscle biopsies were obtained intra-operatively from 10 patients for MEP morphometric analysis. Age at time of surgery ranged from 22-77 years and time from injury to surgery ranged from 2.5-163 months. Shoulder range of motion (ROM) and Medical Research Council (MRC) scores were recorded pre-op and at final follow-up. Results: Surviving MEPs were observed in biopsies of denervated muscles from all patients, even those greater than six months from injury. Average postoperative ROM improvement (assessed between 6-9 months post-surgery) was: forward flexion 84.3 ± 51.8°, abduction 62.5 ± 47.9°, and external rotation 25.3 ± 28.0°. Interpretation: While it is believed that MEP degeneration 6 months post-injury prevents reinnervation, this data details MEP persistence beyond this timepoint along with significant functional recovery after nerve surgery. Accordingly, persistence of MEPs in denervated muscles may predict the extent of functional recovery from nerve repair surgery.

Preoperative Muscle Biopsy to Assess Motor End Plate Integrity as a Predictor for Successful Nerve Transfer: A Case Report.

CASE: A 60-year-old right-hand-dominant man was referred for persistent right deltoid weakness, lateral shoulder numbness, and severe functional deficit 3 months after undergoing proximal humerus open reduction and internal fixation with plate and fibular strut allograft. Deltoid muscle biopsy demonstrated motor end plate (MEP) degeneration. After partial radial-to-axillary nerve transfer, repeat deltoid muscle biopsy revealed successful regeneration of MEPs with reinnervation of deltoid confirmed with postnerve transfer electromyography. CONCLUSION: Selective nerve transfer can successfully rescue a denervated target muscle from further degeneration by restoration of healthy MEPs.

Surgeon-specific factors have a larger impact on decision-making for the management of proximal humerus fractures than patient-specific factors: a prospective cohort study.

BACKGROUND: There is significant variability both in how proximal humerus fractures (PHFs) are treated and the ensuing patient outcomes. The purpose of this study was to investigate which surgeon- and patient-specific factors contribute to decision-making in the treatment of adult PHFs. We hypothesized that orthopedic sub-specialty training creates inherent bias and plays an important role in management algorithms for PHFs. METHODS: We performed a prospective cohort investigation in 2 groups of surgeons-traumatologists (N = 25) and shoulder & elbow/sports surgeons (SES) (N = 26)-and asked them to provide treatment recommendations for 30 distinct clinical cases with standardized radiographic and clinical data. This is a population-based sample of surgeons who take trauma call and treat PHFs with different sub-specializations and practice settings including academic, hospital-employed, and private. Surgeons characterized based on subspecialty (trauma vs. SES), experience level (>10 vs. ≤10-years), and employment type (hospital- vs. non-hospital-employed). Chi-square analyses, logistic mixed-effects modeling, and relative importance analysis were used to evaluate the data. RESULTS: Of the patient-specific factors, we found that the management of PHFs is largely dependent on initial radiographs obtained. Traumatologists were more likely to offer open reduction internal fixation (ORIF) and less likely to offer arthroplasty: 69% ORIF (traumatologists) vs. 51% ORIF (SES, P < .001), 8% arthroplasty (traumatologists) vs. 17% (SES, P < .001). Traumatologists were less likely to change from operative (either ORIF or arthroplasty) to non-operative management compared to SES surgeons when presented with additional patient demographic data. Surgeon-specific factors contributed to more than one-half of the variability in decision-making of PHF management while patient-specific factors contributed to about one-third of the variability in decision-making. CONCLUSIONS: As physicians strive to advance the treatment for PHFs and optimize patient outcomes, our findings highlight the complex overlap between surgeon-, fracture-, and patient-specific factors in the final decision-making process.

Reverse shoulder arthroplasty in rheumatoid arthritis: survival and outcomes.

BACKGROUND: Despite its potential biomechanical advantages, reverse shoulder arthroplasty (RSA) is still considered to be particularly high risk in rheumatoid patients who are osteoporotic and immunodeficient. Our purpose was to report prosthesis survival, complications, and outcomes of RSA in patients with rheumatoid arthritis (RA) at minimum 5-year follow-up. METHODS: We conducted a retrospective multicenter study including 65 consecutive primary RSAs performed in 59 patients with RA between 1991 and 2010. We excluded rheumatoid patients with previous failed anatomic shoulder arthroplasty. Age at surgery averaged 69 years (range, 46-86 years). A structural bone grafting was performed in 18 cases (45%), using the humeral head in 15 cases (BIO-RSA technique), the iliac crest in 2 cases (Norris technique), and an allograft in 1 case. The mean follow-up was 92 months (range, 60-147 months) or until revision surgery. RESULTS: Revision-free survivorship, using Kaplan-Meier curves, was 96% at 7 years. Two patients had revision surgeries for infections, with associated glenoid loosening in 1 case. No humeral loosening was recorded. The mean adjusted Constant score improved from 36% ± 23% preoperatively to 90% ± 26% postoperatively, and mean Subjective Shoulder Value improved from 21% ± 13% to 85% ± 12%, respectively (P < .001). Active anterior elevation increased from 65° ± 43° to 132° ± 27°, active external rotation increased from 10° ± 26° to 22° ± 27°, and internal rotation improved from buttocks to waist (P < .001). Stable fixation of the baseplate was achieved in all cases (including the 6 patients with end-stage RA), and we did not observe bone graft nonunion or resorption. Preoperative radiologic pattern (centered, ascending, or destructive), presence of acromial fractures or tilt (4 cases, 10%), and scapular notching (55%) on final radiographs were not found to influence outcomes or complication rate. Patients with absent/atrophied teres minor had lower functional results. Overall, 95% of the patients were satisfied with the procedure. CONCLUSION: RSA is a safe and effective procedure for the treatment of RA patients, with a low risk of complications and low rate of revision, regardless of the radiologic presentation and stage of the disease. Rheumatoid patients undergoing primary RSA, with or without glenoid bone grafting, can expect a revision-free survival rate of 96% at 7-year follow-up. RSA offers the benefit of solving 2 key problems encountered in rheumatoid shoulders: glenoid bone destruction and rotator cuff deficiency.

Outcomes After Revision Anterior Shoulder Stabilization: A Systematic Review.

BACKGROUND: Primary shoulder stabilization is successful, but there continues to be a risk of recurrence after operative repair, particularly in the young athlete. It is important for surgeons to understand the outcomes after various revision stabilization techniques to best counsel patients and manage expectations. PURPOSE: To analyze recurrent instability and revision surgery rates in patients who underwent revision anterior glenohumeral stabilization procedures with either arthroscopic repair, open repair, coracoid transfer, free bone block, or capsular reconstruction. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: We performed a systematic review of level 2 to 4 evidence studies using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Clinical studies of revision anterior glenohumeral stabilization (arthroscopic repair, open repair, coracoid transfer, free bone block, or capsular reconstruction) with a minimum 2-year follow-up were analyzed. The rate of recurrent instability, rate of revision surgery, patient-reported outcomes, and range of motion were extracted and reported. Study methodological quality was evaluated using the Downs and Black quality assessment score. RESULTS: A total of 37 studies met inclusion criteria and were available for analysis: 20 studies evaluated arthroscopic repair, 8 evaluated open repair, 5 evaluated Latarjet procedure, 3 evaluated bone block, and 2 evaluated capsular reconstruction. There was 1 study included in both arthroscopic and Latarjet procedures, for a total of 1110 revision cases. There was 1 level 2 study, and the remainder were level 3 or 4 with poor Downs and Black scores. Participants analyzed were most commonly young (weighted mean age, 26.1 years) and male (78.4%). The weighted mean clinical follow-up after revision surgery was 47.8 months. The weighted mean rate of recurrent instability was 3.8% (n = 245) after the Latarjet procedure, 13.4% (n = 260) after open repair, 16.0% (n = 531) after arthroscopic repair, 20.8% (n = 72) after bone block, and 31.0% (n = 35) after capsular reconstruction. The weighted mean rate of additional revision surgery was 0.0% after bone block, 0.02% after the Latarjet procedure, 9.0% after arthroscopic repair, 9.3% after open repair, and 22.8% after capsular reconstruction. Patient-reported outcomes and objective measures of range of motion and strength improved with all revision techniques. CONCLUSION: The current review identifies a deficiency in the literature pertaining to consistent meaningful outcomes and the effect of bone loss after revision shoulder stabilization. Published studies demonstrate, however, that revision shoulder stabilization using arthroscopic, open, coracoid transfer, or bone block techniques yielded satisfactory objective and patient-reported outcomes. The Latarjet procedure exhibited the lowest recurrent instability rate. This study confirms that recurrent instability remains a common problem, despite revision shoulder stabilization. The quality of research in revision shoulder stabilization remains poor, and higher quality studies are needed to establish best practices for treatment of this complex problem.

Local versus distal transplantation of human neural stem cells following chronic spinal cord injury.

BACKGROUND CONTEXT: Previous studies have demonstrated functional recovery of rats with spinal cord contusions after transplantation of neural stem cells adjacent to the site of acute injury. PURPOSE: The purpose of the study was to determine if the local or distal injection of neural stem cells can cause functional difference in recovery after chronic spinal cord injury. STUDY DESIGN/SETTING: Twenty-four adult female Long-Evans hooded rats were randomized into four groups, with six animals in each group: two experimental and two control groups. Functional assessment was measured after injury and then weekly for 6 weeks using the Basso, Beattie, and Bresnahan locomotor rating score. Data were analyzed using two-sample t test and linear mixed-effects model analysis. METHODS: Posterior exposure and laminectomy at the T10 level was used. Moderate spinal cord contusion was induced by the Multicenter Animal Spinal Cord Injury Study Impactor with 10-g weight dropped from a height of 25 mm. Experimental subjects received either a subdural injection of human neural stem cells (hNSCs) locally at the injury site or intrathecal injection of hNSCs through a separate distal laminotomy 4 weeks after injury. Controls received control media injection either locally or distally. RESULTS: A statistically significant functional improvement in subjects that received hNSCs injected distally to the site of injury was observed when compared with the control (p=.042). The difference between subjects that received hNSCs locally and the control did not reach statistical significance (p=.085). CONCLUSIONS: The transplantation of hNSCs into the contused spinal cord of a rat led to significant functional recovery of the spinal cord when injected distally but not locally to the site of chronic spinal cord injury.