The rabbit brachial plexus as a model for nerve injury and repair Part 1: Anatomic study of the biceps and triceps innervation.

PURPOSE: Animal models can be helpful in evaluating new surgical strategies for brachial plexus reconstruction. While several groups have already used the rabbit brachial plexus to model injury, reports conflict in anatomic detail and do not identify a nerve-muscle pair to measure motor function recovery after reconstruction. The purpose of the current study is to describe the innervations of the biceps and triceps muscles in rabbits, which are both amenable to study in brachial plexus injury models. MATERIALS AND METHODS: Thirteen rabbits weighing 2-2.5 kg were anesthetized. Six rabbits were sacrificed and dissected using loupe and microscope magnification to understand the overall morphology of the brachial plexus. Seven rabbits underwent electrophysiologic investigation. A bipolar nerve stimulator was used to systematically stimulate the roots, trunks and divisions, and nerve branches of the rabbit brachial plexus and compound muscle action potential was used to record muscle response. Nerve length and width measurements were not recorded. RESULTS: Roots contributing to the brachial plexus were C5, C6, C7, C8, and T1. In contrast to other anatomical studies, T2 did not contribute to the brachial plexus. The triceps was innervated by the radial nerve, which received contributions from C6 (1.6 mA), C7 (1.9 mA), C8, and T1 (12.2 mA).The biceps had dual innervation (proximally and distally). The proximal branch received contributions from C6 (3.5 mA) and C7 (5mA). The distal portion was innervated by a branch from the median nerve, which received innervation from C6, C7, C8, and T1. CONCLUSIONS: The overall structure of rabbit brachial plexus is described and innervation of the biceps and triceps is described in detail. This anatomic investigation will form the basis of a future brachial plexus model of injury and repair.

Brachial plexus nerve injury and repair in a rabbit model part II: Does middle trunk injury result in loss of biceps function while repair results in recovery of biceps function.

INTRODUCTION: There is conflicting anatomic and innervation data regarding the rabbit brachial plexus injury model. This study aims to validate a rabbit brachial plexus injury model. We hypothesize the middle trunk (C6, C7) is the primary innervation of the biceps, and when cut and unrepaired, would demonstrate lack of recovery and when repaired would demonstrate evidence of recovery. MATERIALS AND METHODS: Twenty two male New Zealand white rabbits (3-4 kg) underwent unilateral surgical division of the middle trunk. Five rabbits were randomly assigned to the "no-repair" group while the remaining 17 rabbits underwent direct coaptation ("repair" group). Rabbits were followed for 12 weeks, with ultrasound measurement of biceps cross-sectional area performed preoperatively, and at 4, 8, and 12 weeks postoperatively. At a euthanasia procedure, bilateral compound muscle action potential (CMAP) and isometric tetanic force (ITF) were measured. Bilateral biceps muscles were harvested and wet muscle weight was recorded. The operative side was expressed as a percentage of the non-operated side, and differences between the no repair and repair rabbits were statistically compared. RESULTS: The repair group demonstrated significantly higher CMA (23.3 vs. 0%, p < .05), ITF (25.6 vs. 0%, p < .05), and wet muscle weight (65.8 vs. 52.0%, p < .05) as compared to the unrepaired group. At 4 weeks postoperatively, ultrasound-measured cross-sectional area of the biceps demonstrated atrophy in both groups. At 12 weeks, the repair group had a significantly larger cross-sectional area as compared to the no-repair group (89.1 vs. 59.3%, p < .05). CONCLUSIONS: This injury model demonstrated recovery with repair and lack of function without repair. Longer survival time is recommended for future investigations.

Primary medial femoral condyle vascularized bone graft for scaphoid nonunions with carpal collapse and proximal pole avascular necrosis.

This study aimed to determine the outcome of free vascularized medial femoral condyle bone grafts in the primary treatment of scaphoid nonunions with scaphoid foreshortening or carpal collapse and intraoperatively documented avascular necrosis. Thirty-two patients (28 male, four female) met the inclusion criteria. Median time from injury to surgery was 70 weeks. Thirty of 32 patients healed at a median of 12 weeks. There was significant improvement from preoperative to postoperative lateral intrascaphoid angle, scapholunate angle, and radiolunate angle. Two scaphoids failed to unite; one patient underwent scaphoidectomy and four-corner fusion 15 months postoperatively after suffering a subsequent injury. Another patient underwent 1,2-intercompartmental supraretinacular artery-based vascularized bone grafting at 4 months postoperatively and then scaphoid excision with four-corner fusion 4 years later. The free vascularized medial femoral condyle bone graft restores scaphoid vascularity and architecture while promoting union in a subset of scaphoid nonunions that has historically been a clinical challenge. Level of evidence: IV.

Inter- and Intrarater Reliability of the Thumb Grasp and Pinch Assessment for Children Following Index Pollicization for Congenital Thumb Hypoplasia.

PURPOSE: The Thumb Grasp and Pinch (T-GAP) assessment quantifies functional hand use in children with congenital thumb hypoplasia by categorizing grasp and thumb use patterns during assessment activities that encourage a variety of grasp and pinch styles. This study aims to demonstrate interrater and intrarater reliability results of the T-GAP. METHODS: A retrospective review was performed of children who had undergone index finger pollicization for congenital thumb hypoplasia and subsequent evaluation with videotaping of the T-GAP assessment. Following a training period, 4 occupational therapists scored 11 T-GAP videos on 2 separate occasions, separated by at least 2 weeks. Intraclass correlation coefficients (ICCs), standard error of measurements, minimum detectable change (MDC), and Pearson correlation coefficients were calculated. RESULTS: The T-GAP raw scores were 16 to 55, demonstrating a range of mild to severe hand grasp differences. The ICCs for the interrater reliability trials were 0.887 and 0.901. Intrarater ICCs were all above 0.88. The MDC for each trial was 8.1 and 6.7 points. Pearson correlation coefficients calculated for each rater and each pair of raters were above 0.8 in all cases. CONCLUSIONS: Interrater and intrarater reliability testing results for the T-GAP were excellent in all cases; this strongly suggests that results from T-GAP assessments are reliable. The high ICCs suggest that raters can classify and score children's hand function consistently. CLINICAL RELEVANCE: This study, in conjunction with previous work, suggests that the T-GAP may be an ideal approach to assessing the outcomes of pollicization and provide a means of ongoing assessment of children's grip and pinch function.

Free Vascularized Medial Femoral Condyle Bone Graft After Failed Scaphoid Nonunion Surgery.

BACKGROUND: Outcomes following revision surgery for scaphoid nonunions with osteonecrosis are guarded. We hypothesized that use of free vascularized medial femoral condyle (MFC) bone grafts can lead to healing of the nonunion, increase vascularity of the proximal pole, and restore scaphoid architecture, resulting in acceptable functional outcomes. METHODS: We performed a retrospective review of 49 patients who were treated with an MFC bone graft, between May 2005 and September 2016, after prior failure of operative treatment for scaphoid nonunion. The mean time from the injury to the revision surgery with the MFC bone graft was 24 months, and the mean time from the prior, failed surgery was 15 months. Thirty-six of the 49 patients had had a prior bone graft procedure and 6 patients had had 2 previous surgical procedures for the nonunion. The initial internal fixation of the scaphoid fracture was with a scaphoid screw in 43 patients. All patients had documented osteonecrosis of the proximal pole at the time of our surgery. Carpal indices, time to union, pain scores, functional outcomes, and complications were recorded. RESULTS: Forty-one (84%) of the 49 previously operated on scaphoid nonunions healed at a mean of 16 weeks (range, 9 to 31 weeks) after the MFC bone-grafting as confirmed on computed tomography (CT). Radiographs demonstrated significant improvement in carpal alignment following the surgery with the MFC bone graft. Comparison between preoperative and postoperative values showed a trend toward improved grip strength and no important change in total wrist range of motion. Subsequent procedures were performed in 29 patients, 21 of whom had planned Kirschner wire removal. All 24 patients in whom scaphoid union had been achieved and who were available for follow-up were able to work or attend school full-time, and 88% were satisfied or very satisfied with their wrist function. Age, smoking status, body mass index, time to surgery, and preoperative radiographic findings were not found to be significant predictors of failure. CONCLUSIONS: MFC grafts increase vascularity and restore scaphoid architecture, promoting union in most patients with the combination of proximal pole osteonecrosis, carpal collapse, and failed prior scaphoid nonunion surgery. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A New, Direct Measure of Thumb Use in Children After Index Pollicization for Congenital Thumb Hypoplasia.

PURPOSE: After index pollicization for congenital thumb hypoplasia, time-based hand dexterity tests do not indicate whether the new thumb is being used by a child. The Thumb Grasp and Pinch assessment (T-GAP) is a new outcome measure that classifies grasp and pinch styles to quantify use of the new thumb. The goal of this study was to establish concurrent validity and construct validity in the T-GAP. METHODS: Data from children treated with index finger pollicization for congenital thumb hypoplasia were retrospectively reviewed. Measures of strength, range of motion, and scores on the Box and Blocks Test (BBT), 9-Hole Peg Test (NHPT), Functional Dexterity Test (FDT), and Task 7 (Heavy Objects) from the Jebsen-Taylor Test (JTT7) were recorded. Patients also completed the T-GAP consisting of 9 age-appropriate tasks, during which grasp patterns were classified. Spearman correlation coefficients were calculated comparing the T-GAP score with scores on the BBT, NHPT, FDT, and JTT7. RESULTS: We evaluated 21 thumbs in 21 children an average of 71.7 months after pollicization surgery (range, 9-175 months). The T-GAP score was significantly correlated with BBT, NHPT, FDT, and JTT7 (R = 0.69, -0.60,-0.59, and -0.60, respectively). The T-GAP score was significantly correlated with tripod pinch, key pinch, and grip strength (R = 0.77, 0.75, and 0.71, respectively) and with opposition and grasp span (R = 0.50 and 0.52, respectively). The T-GAP was the only functional measure correlated with parent and patient satisfaction with thumb function. CONCLUSIONS: Concurrent validity was supported by significant correlations between T-GAP score for all 4 dexterity measures. Construct validity was supported by significant correlations between strength and range of motion of the thumb and T-GAP score. CLINICAL RELEVANCE: This evaluation may help surgeons and therapists better understand results after pollicization and determine whether the new thumb is being incorporated into daily activities.

Change in Hand Function and Dexterity with Age after Index Pollicization for Congenital Thumb Hypoplasia.

BACKGROUND: Little is known about how performance on strength, range of motion, and dexterity measures changes as children with index finger pollicization mature. The authors reviewed performance in range of motion, strength, and dexterity over a 7-year period and report outcomes over time. METHODS: Data from children treated with index finger pollicization for congenital thumb hypoplasia from 2007 to 2014 were reviewed retrospectively. Children were followed for an average of 3.9 years (range, 1 to 7 years) during the study period. Standardized assessments included range of motion, grip, key pinch and tripod pinch strength, the Box and Block Test, the Nine Hole Peg Test, and the Functional Dexterity Test. Average score by age and average yearly change were calculated for each assessment, and scores were plotted against published age-matched scores of normal children when available. RESULTS: Twenty-three patients with 29 affected thumbs were included. Distal grasp span increased 0.17 inch and Kapandji opposition improved 0.26 point with each year of age; however, proximal web-space size did not increase over time. Grip strength improved an average of 2.69 kg/year, and tripod and key pinch improved 0.58 kg and 0.67 kg with each year of age. Box and Block Test scores improved an average of 4.11 blocks/year. Scores on the Nine Hole Peg Test improved 3.83 seconds/year, and scores on the Functional Dexterity Test improved 0.026 peg/second each year. CONCLUSIONS: Children with pollicized thumbs improve in dexterity and strength with growth. Web-space size did not change with age; therefore, the thumb should be carefully positioned at the time of surgery. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Validation of Isometric Tetanic Force as a Measure of Muscle Recovery After Nerve Injury in the Rabbit Biceps.

PURPOSE: The purpose of this study was to describe and validate a technique for measurement of isometric tetanic force (ITF) in the rabbit biceps muscle. MATERIALS AND METHODS: Eighteen New Zealand White rabbits were randomized to test either the right side or the left side first. Under propofol anesthesia, the brachial plexus and biceps brachii were exposed. The middle trunk (C6, C7) was secured in a bipolar electrode. Compound muscle action potential (CMAP) was measured. The proximal, tendinous portion of the biceps was severed at the shoulder and clamped in a custom-made force transducer. Muscle preload and electrical stimulation variables were optimized to obtain the highest tetanic muscle contraction. Wet muscle weight (WMW) and nerve histomorphometry were analyzed. Statistical analysis was performed to determine side-to-side equivalence. RESULTS: The rabbit biceps muscle force demonstrated side-to-side equivalence with overlapping 95% confidence intervals (95% CI). The right side, expressed as a percentage of the left, averaged 99.69% (95% CI, 88.89%-110.5%). The WMW of the right expressed as a percentage of the left was 98.9% (95% CI, 95.8%-102%). CONCLUSIONS: The ITF is equivalent from side to side in the rabbit as demonstrated by the high degree of overlap in the 95% CIs for each side. The width of the 95% CI implies that there is more variability in the rabbit upper extremity than for the lower extremity of the rabbit or rat models, and researchers should take this into account when performing sample size estimates in pre-experimental planning. CLINICAL RELEVANCE: The rabbit biceps muscle ITF measurements can be used to measure motor recovery in a rabbit model of brachial plexus injury and compared with the contralateral uninjured side.

A novel computational method for evaluating osteochondral autografts in distal radius reconstruction.

BACKGROUND: We describe a novel computational method for assessing the fit of an osteochondral graft. We applied our software to five normal wrist computed tomography (CT) scans to determine the fit of the scaphoid to the lunate fossa of the distal radius. METHODS: CT scans of five wrists were digitally rendered. The capitate facet of the scaphoid was fit to the lunate fossa of the distal radius using custom software based on the iterative closest point (ICP) algorithm. This approach iteratively determines the optimal position of a model surface to minimize the sum of squares of distances from all points on a target surface. The fit of the two surfaces was reported by calculating the mean residual distance (MRD) between each point on one surface and its nearest neighbor on the other. RESULTS: The MRD for the five subjects was found to be 0.25 mm, with 82.8-98.3 % of the articular surfaces within 0.5 mm of each other. CONCLUSIONS: We have developed a software algorithm for comparing two articular surfaces to test fit for a proposed joint reconstruction. The software is versatile and may be applied to any bony surface to identify new graft donor sites. The fit assessment renders a richer, three-dimensional understanding of the fit of the graft as compared to traditional two-dimensional assessments. LEVEL OF EVIDENCE: Decision analysis, Level V.

Prospective randomized controlled trial comparing 1- versus 7-day manipulation following collagenase injection for dupuytren contracture.

PURPOSE: To compare the efficacy, tolerance, and safety of manual manipulation at day 7 to day 1 following collagenase Clostridium histolyticum (CCH) injection for Dupuytren contracture. METHODS: Eligible patients were randomized to manipulation at day 1 versus day 7 following CCH injection. Preinjection, premanipulation, postmanipulation, and 30-day follow-up metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joint contractures were measured. Pain scores were recorded at each time point. Data were stratified per cohort based on primary joint treated (MCP vs PIP). Means were compared using paired and unpaired t-tests. RESULTS: Forty-three patients with 46 digits were eligible and were randomized to 1-day (22 digits) and 7-day (24 digits) manipulation. For MCP joints, there were no significant differences in flexion contractures between 1- and 7-day cohorts for initial (47° vs 46°), postmanipulation (0° vs 2°), or 30-day follow-up (1° vs 2°) measurements. Premanipulation, the residual contracture was significantly lower in the 7-day group (23° vs 40°). For PIP joints, there were no significant differences between 1- and 7-day cohorts for initial (63° vs 62°), premanipulation (56° vs 52°), postmanipulation (13° vs 15°), or 30-day (14° vs 16°) measurements. There were no significant differences in pain or skin tears between the 2 groups. No flexor tendon ruptures were observed. CONCLUSIONS: The effectiveness of CCH in achieving correction of Dupuytren contractures was preserved when manipulation was performed on day 7, with no differences in correction, pain, or skin tears. These data suggest that manipulation can be scheduled at the convenience of the patient and surgeon within the first 7 days after injection. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.

Radiographic evaluation of the modified Brunelli technique versus a scapholunotriquetral transosseous tenodesis technique for scapholunate dissociation.

PURPOSE: To compare reduction of the scapholunate articulation using a transosseous tenodesis through the scaphoid, lunate, and triquetrum (SLT) with the modified Brunelli technique (MBT) in a cadaver model, as measured by scapholunate (SL) angle and diastasis on radiographs. METHODS: Twelve fresh-frozen cadaveric wrists were radiographically examined in a neutral posture, ulnar deviation, and clenched fist position. The SL angle and diastasis were recorded in each position with the SL ligament intact, after sectioning the ligament and secondary restraints, and after reconstruction by either the MBT (6 wrists) or SLT technique (6 wrists). Wrists were cycled through their maximum flexion and extension arc 100 times to simulate wrist motion after ligament sectioning and reconstruction. RESULTS: After sectioning and cycling, all wrists demonstrated radiographic evidence of SL diastasis. After ligament reconstruction and cycling, there was no statistically significant difference in diastasis in the MBT reconstructions compared with the SLT reconstructions (3.0 vs 2.4 mm). The SLT group demonstrated better maintenance of the restored SL angle than the MBT reconstructions. CONCLUSIONS: In this cadaveric model, both MBT and SLT reconstructions restored anatomic parameters in the SL joint, with correction of SL diastasis and SL angle. Future studies to assess the clinical outcomes of SLT tenodesis in patients with chronic SL disruptions are important. CLINICAL RELEVANCE: The SLT tenodesis, with a central biologic tether along the SL axis and dorsal reinforcement, may prove clinically useful.

Metacarpal fractures: treatment and complications.

Metacarpal fractures comprise between 18-44 % of all hand fractures. Non-thumb metacarpals account for around 88 % of all metacarpal fractures, with the fifth finger most commonly involved [19]. The majority of metacarpal fractures are isolated injuries, which are simple, closed, and stable. While many metacarpal fractures do well without surgery, there is a paucity of literature and persistent controversy to guide the treating physician on the best treatment algorithm. The purpose of this article is to review non-thumb metacarpal anatomy and treatment protocols for nonoperative management of stable fractures, and compare existing literature on surgical techniques for treatment of acute fractures and complications.

Migration of trochanteric cerclage cable debris to the knee joint.

Migrating orthopedic hardware has widely been reported in the literature. Most reported cases of migrating hardware involve smooth Kirschner wires or loosening/fracture of hardware involved with joint stabilization/fixation. It is unusual for hardware to migrate within the soft tissues. In some cases, smooth Kirschner wires have migrated within the thoracic cage-a proposed mechanism for this phenomenon is the negative intrathoracic pressure. While wires have also been reported to gain access to circulation, transporting them over larger distances, the majority of broken or retained wires remain local. We report a case of a 34-year-old man in whom numerous fragments of braided cable migrated from the hip to the knee.

Mifepristone and misoprostol for early pregnancy failure: a cohort analysis.

OBJECTIVE: We sought to examine outcomes of mifepristone and misoprostol for early pregnancy failure (EPF) treatment in a nonresearch setting. STUDY DESIGN: A protocol was developed for physicians to use mifepristone 200 mg orally and misoprostol 800 µg vaginally for EPF. Success rates were analyzed and an adjusted multivariable regression was used to identify factors predictive of success. RESULTS: Treatment success occurred in 99 (80%; 95% confidence interval, 72-87%) of 123 patients after mifepristone and a single dose of misoprostol and 102 (83%; 95% confidence interval, 75-89%) patients overall. The odds of successful medical treatment were increased in women with a diagnosis of intrauterine embryonic/fetal demise (odds ratio, 3.80) and decreased in women who made additional emergency department visits (odds ratio, 0.12). CONCLUSION: Patients and clinicians may be more likely to intervene surgically with an EPF when a strict study protocol is not being followed.