Anterior Interosseous Nerve Syndrome: Is it a Compressive Neuropathy?

BACKGROUND: Anterior interosseous nerve (AIN) syndrome is a rare disease whose pathophysiology is controversial. Despite efforts to elucidate the pathophysiology of AIN syndrome, it has not yet been resolved. We reinterpret electrodiagnostic studies, magnetic resonance imaging (MRI), and surgical findings to clarify the pathophysiology of AIN syndrome. MATERIALS AND METHODS: In this retrospective case series, we included surgically treated 20 cases of nontraumatic AIN syndrome. Surgery was performed after a minimum of 12 weeks of conservative treatment. The clinical data and operation records were extracted from the medical records for analysis. All electrodiagnostic tests were reinterpreted by physicians with an American Board Certification in electrodiagnostic medicine. Moreover, every contrast-enhanced MRI performed during the assessment was reviewed by a musculoskeletal radiologist. RESULTS: Of the twenty re-analyzed cases, nine AIN syndromes (45%) showed abnormal electromyography in non-AIN innervated muscles. Sensory nerve conduction studies were normal in all cases. Five magnetic resonance images (46%) showed signal changes in non-AIN-innervated muscles. Only four cases (20%) revealed definitive compression of the AIN during surgery. CONCLUSIONS: Electrodiagnostic study and MRI indicated that many patients with AIN syndrome exhibited a diffuse pathologic involvement of the motor component of the median nerve. We conclude that the main pathophysiology of AIN syndrome would be diffuse motor fascicle neuritis of the median nerve in the upper arm.

Low vitamin D levels in post-menopausal women are associated with complex regional pain syndrome type I in surgically treated distal radius fractures.

BACKGROUND: Complex regional pain syndrome type I (CRPS I) is a chronic devastating condition and a relatively common complication of distal radius fractures (DRF). The purpose of this study was to investigate the relationship of vitamin D levels in surgically treated post-menopausal women with CRPS I occurrence in DRF. METHODS: From February 2016 to March 2017, 158 surgically treated post-menopausal patients with DRF were enrolled. Exclusion criteria were (1) patients who had been taking vitamin D or osteoporosis medication at the time of injury; (2) patients with medical factors that may affect vitamin D levels; (3) patients who were reluctant to enroll in the study; and (4) patient with additional fractures, ligamentous injuries, or neuropathy. A total of 107 patients were available for final analysis. We compared the serum vitamin D levels in post-menopausal women with DRF with CRPS I (group 1) and without CRPS I (group 2). Bone mineral density (BMD) of the femur and spine, osteocalcin, alkaline phosphatase (ALP), body mass index (BMI) were also measured. RESULTS: The average age at the time of surgery was 66.5 years (range, 39-86 years). The mean follow-up period was 16.3 months after surgery. Among the 107 surgically treated DRF patients, 19 (18%) met the Budapest criteria for CRPS I during the follow-up period. The mean serum vitamin D level in group 1 (15.2 ng/ml) was significantly lower than that in group 2 (20.5 ng/ml, p = 0.027). The mean values of osteocalcin, ALP, BMI, and BMD were not significantly different between the groups. CONCLUSION: Lower vitamin D levels in post-menopausal women can increase CRPS I occurrence in distal radius fractures.

Small joint arthrodesis technique using a dowel bone graft in a rabbit model.

The dowel bone graft fusion technique for the ankle is a well-known and useful method. However, clinical results of dowel bone graft for small joint fusion are unknown. The objective of the present study is to evaluate the effects of dowel bone graft technique for small joint arthrodesis in an in vivo arthrodesis of rabbit elbow model compared with the conventional arthrodesis technique (open, joint surface debridement, and internal fixation method). We assigned 28 young adult New Zealand white rabbits to one of two groups: Group 1, the conventional fusion technique group; Group 2, the dowel bone graft fusion technique group. We performed arthrodesis surgery in two different ways for each group. Eight weeks after the operation, specimens were harvested, radiographed, mechanically tested for torque to failure and stiffness, and evaluated for histology. Fusion rates were 77% (10/13) in Group 1 and 93% (13/14) in Group 2 (p = 0.326). Torque to failure showed a mean of 0.86 Nm in Group 1 and 0.77 Nm in Group 2 (p = 0.464). The mean value of stiffness was 0.11 Nm/deg in Group 1 and 0.11 Nm/deg in Group 2 (p = 0.832). In Group 2, histological examination showed residual cartilage absorption and inflammatory response in all cases. In this model, we have been unable to show a difference in either the union rate or strength of fusion between the two methods. However, the dowel bone graft technique is an easy and less invasive method and has some advantages over the conventional method.

Modified triceps fascial tongue approach for primary total elbow arthroplasty.

BACKGROUND: Triceps weakness is a common complication of total elbow arthroplasty (TEA). Many posterior approaches for TEA have been introduced to maintain triceps function. The present study evaluated the clinical outcomes and extensor strengths of primary TEA with modified triceps fascial tongue approach. METHODS: Twenty-one primary TEAs performed in 20 patients by a single surgeon were reviewed with a mean of 64.2 months (range, 24-127 months) of follow-up. Every TEA was performed using the modified triceps fascial tongue approach, with the Coonrad-Morrey prosthesis. Patient demographics, range of motion, pain visual analog scale, and triceps strength (Medical Research Council [MRC] scale) were compared before and after the operation. The Mayo Elbow Performance Score was evaluated at the latest follow-up. RESULTS: Triceps strength was normal (MRC grade V) in 10 elbows (48%) and good (MRC grade IV) in 11 (52%). Triceps strength after arthroplasty was significantly improved compared with the preoperative strength (P < .001). Mean flexion arc was improved from 78° to 100° after arthroplasty (P = .004). However, mean flexion contracture (preoperative; 29°, postoperative; 26°) was not improved after surgery (P = .377). The mean visual analog scale pain score improved from 7.7 preoperatively to 2.4 postoperatively (P < .001). Postoperative Mayo Elbow Performance Scores were excellent in 13 elbows, good in 6, and fair in 2. The only complications were 3 intraoperative condylar fractures. CONCLUSIONS: Modified triceps fascial tongue approach is an easy and effective approach for primary TEA.