BACKGROUND: In daily clinical practice, it is essential to properly evaluate the postoperative sliding distance of various femoral head fixation devices (HFD) for trochanteric fractures. Although it is necessary to develop an accurate and reproducible method that is unaffected by inconsistent postoperative limb position on radiography, few studies have examined which method is optimal. Therefore, the purpose of this study is to prospectively compare the accuracy and reproducibility of our four original methods in the measurement of sliding distance of the HFD. METHODS: Radiographs of plastic simulated bone implanted with Japanese proximal femoral nail antirotation were taken in five limb postures: neutral, flexion, minute internal rotation, greater external rotation, and flexion with external rotation. Orthopedic surgeons performed five measurements of the sliding distance of the HFD in each of the flowing four methods: nail axis reference (NAR), modified NAR, inner edge reference, and nail tip reference. We also assessed two clinical cases by using these methods and evaluated the intraclass correlation coefficients. RESULTS: The measured values were consistent in the NAR method regardless of limb posture, with an even smaller error when using the modified NAR method. The standard deviation (SD) was high in the nail tip reference method and extremely low in the modified NAR method. In the two clinical cases, the SD was the lowest in the modified NAR method, similar to the results using plastic simulated bone. The intraclass correlation coefficients showed the highest value in the modified NAR method. CONCLUSIONS: We conclude that the modified NAR method should be the most recommended based on its accuracy, reproducibility, and usefulness.
*Bone Nails ; *Dimensional Measurement Accuracy ; Fracture Fixation, Intramedullary/instrumentation/*methods ; Hip Fractures/*surgery ; Prospective Studies ; Reproducibility of Results

Background: Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a relatively newly identified clinical condition that manifests as trismus with a square-shaped mandible. Herein, we report a case of MMATH that was initially misdiagnosed for polymyositis due to trismus and simultaneous lower limb pain, with literature review.Case presentation A 30-year-old woman had a history of lower limb pain after exertion for 2 years. Initial physical examination had been performed at the Department of General Medicine in our hospital. There was also redness in the hands and fingers. Although polymyositis was suspected, it was denied. The patient visited our department for right maxillary wisdom tooth extraction.Clinical examination revealed that the patient had a square-shaped mandible. The maximal mouth opening was 22 mm. There was no temporomandibular joint pain at the time of opening. Furthermore, there was awareness of clenching while working. Panoramic radiography revealed developed square mandibular angles with flattened con‑ dyles. Computed tomography showed enlarged masseter muscles with high-density areas around the anterior and lateral fascia. Magnetic resonance imaging also showed thickened tendons and aponeuroses on the anterior surface and inside bilateral masseter muscles. Finally, the patient was diagnosed with MMTAH. Bilateral aponeurectomy of the masseter muscles with coronoidectomy and masseter muscle myotomy was performed under general anesthesia.The maximum opening during surgery was 48 mm. Mouth opening training was started on day 3 after surgery. Histo‑ pathological examination of the surgical specimen showed that the muscle fibers were enlarged to 60 μm. Immuno‑ histochemistry testing for calcineurin, which was associated with muscle hypertrophy due to overload in some case reports, showed positive results. Twelve months after surgery, the mouth self-opening and forced opening were over 35 mm and 44 mm, respectively. Conclusions Herein, we report a case of MMATH. Lower limb pain due to prolonged standing at work and overload due to clenching were considered risk factors for symptoms onset of MMATH.