Biomechanical evaluation of proximally placed femoral less-invasive stabilization system plates.

Loss of fixation of the Synthes 13-hole femoral Less-Invasive Stabilization System (LISS) plate has been noted. The biomechanical stability of this plate may be affected by improper proximal placement. We conducted a study to determine if there is any difference in fixation failure, deformation, or stiffness based on proximal placement. Using synthetic composite bones, we created a comminuted supracondylar distal femur fracture, AO/OTA (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association) 33-A3. Three groups of 9 femurs each were created: 1 correctly positioned group and 2 incorrectly positioned groups, 1 with the proximal aspect of the plate 1 cm anterior and 1 with the proximal aspect of the plate 1 cm posterior. The constructs were tested in axial, torsional, and cyclical axial modes to assess plastic and total deformation and stiffness. Under axial loading, the posteriorly placed plate showed a 16.4% increase in stiffness. There was a significant increase of 12% in torsional stiffness in the anteriorly placed plate. Under cyclical axial loading, there was a significant increase of 14% in total deformation in the anteriorly placed plate. No fixation failure was observed. One-centimeter variation in proximal placement of a 13-hole LISS plate in a synthetic composite fracture model had little effect on the overall construct.

The change of whole lumbar segmental motion according to the mobility of degenerated disc in the lower lumbar spine: a kinetic MRI study.

PURPOSE: To analyze the effects of mobility of degenerated disc in the lower lumbar discs (L4-5 and L5-S1) on both whole lumbar motion and adjacent segment ROM. METHODS: The kMRIs with disc degeneration at L4-5 or L5-S1 were classified into three groups: the normal group, the motion-preserved (MP) group and the motion-lost (ML) group based on range of motion (ROM) of 5° in the degenerated segment. Each segmental ROM, whole lumbar motion, and the contribution % of the upper lumbar spine (ULS: L1-2-3) and the lower lumbar spine (LLS: L4-5-S1) motion to whole lumbar motion were measured and compared with each of the other groups. RESULTS: There were 94, 99 and 66 patients in the normal group, MP group and ML group, respectively. The normal group showed no significant difference compared to the MP group in all ROM parameters. The ML group showed significantly less whole lumbar motion, more contribution % in the ULS and less in the LLS than the normal and the MP groups. The ROM in the superior adjacent segment in the ML group was not significantly different between that in the normal and MP group. CONCLUSIONS: Degenerated lumbar discs did not show hypermobility within functional ROM. Loss of segmental ROM from advanced disc degeneration did not cause an increase in the ROM of the superior adjacent segment in vivo. When the LLS had motion-lost, advanced disc degeneration, whole lumbar motion was significantly decreased and compensatory increase in ROM was accomplished by the ULS.

Three-wire fixation technique for displaced fifth metatarsal base fractures.

Fractures of the tuberosity of the fifth metatarsal are the most common type of fifth metatarsal fractures. This particular fracture usually produces low morbidity and low rates of nonunion when treated nonoperatively. However, on occasion, significant displacement, comminution, or significant intra-articular involvement may warrant operative intervention. Multiple techniques have been described for the operative care of this fracture. We present a somewhat simplified fixation method for displaced fifth metatarsal fractures in a small set of patients who were all followed up to final healing of the fracture.

Treatment of Jones fracture nonunion with isolated intramedullary screw fixation.

Although the treatment of acute Jones fractures is well described in published studies, the Jones fracture nonunion is more controversial with regard to treatment. Although nonoperative treatment is an option, surgery is the usual course. We conducted a retrospective case series of 7 patients (1 man and 6 women; age range 39 to 54 years), who were initially treated nonoperatively for acute Jones fractures. They went on to develop nonunions and were treated with intramedullary screw fixation. All patients had healed radiographically by 11 weeks postoperatively. One screw (14.29%) required removal because of irritation. None of the patients to date have experienced a new fracture. Our results indicate that intramedullary screw fixation alone without bone grafting is a viable option for Jones fracture nonunions.