Orthogonal pin construct versus parallel uniplanar pin constructs for pelvic external fixation: a biomechanical assessment of stiffness and strength.

OBJECTIVE: The purpose of this study is to compare the structural stiffness of an orthogonal pelvic external fixator pin construct with 2 different parallel external fixator pin constructs in a simulated bone model. HYPOTHESIS: An orthogonal pelvic external fixator pin construct would be significantly more stiff than a parallel pin construct when loaded in-plane under similar conditions. DESIGN: Thirty synthetic pelvic bone models were configured with orthogonal pins (group 1), parallel iliac crest pins (group 2), or parallel supra-acetabular pins (group 3). Specimens were loaded either in-plane (flexion/extension moment) or out-of-plane (internal/external rotation moment) to assess construct stiffness. SETTING: Orthopaedic industry mechanical testing laboratory (Stryker Orthopedics, Mahwah, NJ). INTERVENTION: Single load cycle to failure with load application modified to assess stiffness both in-plane and out-of-plane with the pin constructs. MAIN OUTCOME MEASURE: Pelvic external fixation pin construct stiffness. RESULTS: Stiffness for in-plane loading was 150.2 +/- 51.2 N/mm for the orthogonal pin construct, 105.0 +/- 46.9 N/mm for the iliac crest pin construct, and 104.7 +/- 20.7 N/mm for the supra-acetabular pin construct. Pairwise comparisons demonstrated that the difference was significant (P < 0.05) between groups 1 and 2 and groups 1 and 3 but not between groups 2 and 3. Stiffness for out-of-plane loading was 49.6 +/- 3.4 N/mm for the orthogonal pin construct, 53.9 +/- 3.5 N/mm for the iliac crest pin construct, and 100.6 +/- 4.3 N/mm for the supra-acetabular pin construct, with significant differences (P < 0.05) between groups 1 and 3 and groups 2 and 3 but not between groups 1 and 2. CONCLUSION: An orthogonal pelvic external fixator pin construct produced a significantly stiffer construct for in-plane loading (flexion/extension moment) compared with either parallel pin construct; however, a parallel supra-acetabular pin construct was stiffer for out-of-plane loading.

Radiographic and clinical comparisons of distal tibia shaft fractures (4 to 11 cm proximal to the plafond): plating versus intramedullary nailing.

OBJECTIVE: The purposes of this study were to review distal tibia shaft fractures treated with a plate or a nail and to assess the clinical and radiographic results, complication rates, and the need for secondary procedures. DESIGN: Retrospective review. SETTING: Two Level I trauma centers. PATIENT/PARTICIPANTS: We retrospectively reviewed 111 patients with 113 extra-articular distal tibia fractures between 4 and 11 cm proximal to the plafond. Seventy-six were treated with an intramedullary nail and 37 were treated with a medial plate. Twenty-nine (27%) of the concomitant fibula fractures were fixed. MAIN OUTCOME MEASUREMENTS: Complications and secondary procedures were evaluated in 111 patients after a mean of 24 months (range, 12-84 months). RESULTS: A total of 111 patients with 113 fractures of the distal tibia were reviewed. Their mean age was 39.1 years, 69% were men, and 30% had open fractures. Four patients underwent additional procedures for soft tissue coverage. None of these had infection. Five patients (4.4%) developed osteomyelitis: four after intramedullary nailing (5.3%) and one after plating (2.7%). Nine patients (12%) had delayed union or nonunion after nailing. One patient (2.7%) had a nonunion after plating (P = 0.10). Nonunion was more common after concurrent fixation of the fibula (14% versus 2.6%, P = 0.04). Angular malalignment of > or =5 degrees occurred in 22 patients with nails (29%) and 2 with plates (5.4%, P = 0.003). Eight patients had malunions of > or =10 degrees. Valgus was the most common deformity (n = 16). Malunion was more common after open fracture (38%, P = 0.006) but was not related to fibula fixation. Painful hardware was removed in six patients (7.9%) with nails and in two patients (5.4%) with plates. CONCLUSIONS: Distal tibia fractures may be treated successfully with plates or nails. Delayed union, malunion, and secondary procedures were more frequent after nailing. Randomized prospective assessment may further clarify these issues and provide information about costs associated with these fractures.

A cadaver study of the trochanteric pelvic clamp for pelvic reduction.

OBJECTIVE: The purpose of this study is to evaluate the ability of the trochanteric pelvic clamp to reduce anterior-posterior compression pelvic ring disruptions. DESIGN: Eight fresh-frozen cadavers underwent sequential disruption of the pelvic ring to represent both anterior-posterior compression type II (APC II) and anterior-posterior compression type III (APC III) injury patterns. Reduction with the trochanteric pelvic clamp was performed. Prereduction and postreduction anterior/posterior pelvic displacements were determined radiographically. SETTING: Institutional research laboratory. INTERVENTION: Application of a trochanteric pelvic clamp to reduce a pelvic ring disruption. MAIN OUTCOME MEASURE: Radiographic measurements of anterior and posterior pelvic displacement were evaluated and compared to similar values after reduction with the trochanteric pelvic clamp. RESULTS: The application of the trochanteric pelvic clamp to simulated APC II and APC III pelvic injuries in a cadaver model demonstrated a significant reduction of the anterior pubic diastasis and the posterior disruption of the sacroiliac joint. Anterior pelvic vertical displacement did not improve with application of the trochanteric pelvic clamp. Measurement of symphysis diastasis for APC II injuries was 4.07 cm (+/-0.31) prereduction and 0.38 cm (+/-0.18) postreduction, (P < 0.001); for APC III injuries, 6.32 cm (+/-0.84) prereduction and 1.24 cm (+/-1.01) postreduction, (P < 0.001). For posterior sacroiliac disruptions, APC II injury measurements were 1.81 cm (+/-0.35) prereduction and 0.69 cm (+/-0.32) postreduction (P < 0.001); for APC III injuries, 3.81 cm (+/-1.06) prereduction and 1.86 cm (+/-0.82) postreduction (P = 0.002). At the symphysis pubis, APC II vertical displacement was 0.32 cm (+/-0.36) prereduction and 0.30 cm (+/-0.38) postreduction (P < 0.740); for APC III injuries, 0.5 cm (+/-0.31) prereduction and 0.88 cm (+/-0.53) postreduction (P < 0.098). CONCLUSIONS: The application of the trochanteric pelvic clamp is reliable for obtaining reduction of anterior-posterior compression pelvic injuries in a cadaver model.

Surgical treatment of nonarticular distal tibia fractures.

Distal tibia metaphyseal fractures can be difficult to manage. Treatment selection is influenced by the proximity of the fracture to the plafond, fracture displacement, comminution, and injury to the soft-tissue envelope. Nonsurgical management is possible for stable fractures with minimal shortening. Indications for intramedullary nailing have expanded to include distal metaphyseal tibia fractures. Intramedullary nailing allows atraumatic, closed stabilization while preserving the vascularity of the fracture site and integrity of the soft-tissue envelope. Intramedullary canal anatomy at this level prevents intimate contact between the nail and endosteum, however, and concerns have been raised regarding the biomechanical stability of fixation and risk of malunion. Plate fixation is effective in stabilizing distal tibia fractures. Conventional techniques involve extensive dissection and periosteal stripping, which increase the risk of soft-tissue complications. Percutaneous plating techniques use indirect reduction methods and allow stabilization of distal tibia fractures while preserving vascularity of the soft-tissue envelope. External fixation is effective in the setting of contaminated wounds or extensive soft-tissue injury. Careful preoperative planning with consideration for fracture pattern and soft-tissue condition helps guide implant selection and minimize postoperative complications.

Effect of neoadjuvant chemotherapy on distraction osteogenesis in the goat model.

Neoadjuvant chemotherapy potentially can have an adverse effect on bone healing in distraction osteogenesis whether given before or concomitant with distraction osteogenesis. It was the purpose of the current study to determine if administration of chemotherapy before distraction adversely affects bone generation in distraction osteogenesis. Twenty-four adult dairy goats were divided randomly into two groups: a control group having distraction osteogenesis only and a chemotherapy group, receiving one course of Adriamycin before distraction osteogenesis. The animals were sacrificed at 6 weeks, 12 weeks, or 24 weeks and the lengthened tibias were evaluated by radiologic studies, biomechanical testing, and histologic analysis. All goats receiving chemotherapy showed systemic adverse effects. In a multifactorial analysis of the lengthened bones, there was no statistically significant difference between the control goats versus goats that received chemotherapy; indicating that there was no sustained inhibitory effect on bone formation by the chemotherapy. These findings suggest that a prior course of chemotherapy with Adriamycin may not be a contraindication to limb lengthening for limb salvage after resection of an osteosarcoma.