Treatment of both simple and complex patella fractures is a challenging clinical problem. The aim of this study was to investigate the biomechanical performance of recently developed lateral rim variable angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures.

Twelve pairs of human anatomical knees were used to simulate either two-part transverse simple AO/OTA 34C1 or five-part complex AO/OTA 34C3 patella fractures by means of osteotomies, with each fracture model created in six pairs. The complex fracture pattern was characterized by a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral, and an inferior fragment mimicking comminution around the distal patellar pole. The specimens with simple fractures were pairwise assigned for fixation with either tension band wiring through two parallel cannulated screws, or a lateral rim variable angle locking plate. The knees with complex fractures were pairwise treated with either tension band wiring through two parallel cannulated screws plus circumferential cerclage wiring, or a lateral rim variable angle locking plate.

Each specimen was tested over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within the range of 90° flexion to full knee extension. Interfragmentary movements were captured via motion tracking.

For both fracture types, the longitudinal and shear articular displacements measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following the lateral rim variable angle locked plating compared with tension band wiring, p<0.01.

Lateral rim locked plating of both simple and complex patella fractures provides superior construct stability versus tension band wiring under dynamic loading.

Malreduction of the syndesmosis is a poor prognosticator following ankle fracture and has been documented in as many as 52% of patients following fracture fixation. The current standard for assessment of reduction of the syndesmosis is bilateral computed tomography (CT) scan of the ankle. Multiple radiographic parameters are utilized to define malreduction, however, there has been limited investigation into the accuracy of these measurements to differentiate malreduction from inherent anatomical asymmetry. The purpose of this study was to identify the prevalence of positive malreduction standards within the syndesmosis of native, uninjured ankles.

Bilateral lower extremity CT scans including ankles were screened. Studies were excluded if the patient was skeletally immature, had pathology below the knee or if they had congenital neuromuscular syndromes. The resulting cohort consisted of 207 patients. The indication for bilateral CT scan was femoral acetabular impingement in 110 patients (53%), rotation assessment following arthroplasty in 32 patients (15%), rotation assessment following femoral fracture in 30 patients (14%), rotational assessment for patellar instability in 30 patients (14%) and five miscellaneous indications (2%).

Fifty patients were reviewed by three observers independently and to determine inter-observer reliability. A single observer repeated the measurements within the same cohort four weeks later to evaluate intra-observer reliability. Three observers then measured the anterior syndesmotic distance, posterior syndesmotic distance, central syndesmotic distance, fibular rotation and sagittal fibular translation at 1cm from the distal tibial articular surface. Overall side to side variability between the left and right ankle were assessed. Previously studied malreduction standards were evaluated. These included: anterior to posterior syndesmotic distance > 2mm, central syndesmotic difference > 1.5mm, average syndesmotic distance > 2mm, fibular rotational difference > 10o and sagittal translational difference > 2mm.

The inter- and intra-observer reliability was good to excellent for anterior, posterior and central syndesmotic distance, and fibular rotation measurements. Sagittal fibular translation had an ICC of 0.583, and thus was only of fair reliability. Side to side comparison revealed statistically significant difference in only anterior syndesmotic difference (p=0.038). A difference of anterior to posterior syndesmotic distance of greater than 2mm was observed in 43 patients (20.2%). Thirty eight patients (17.8%) had a central syndesmotic difference of greater than 1.5mm. A fibular rotational difference of greater than 10o was observed in 49 patients (23%). The average difference between the anterior and posterior syndesmosis was greater than 2mm in 17 patients (8.2%). Nine patients (4.2%) had sagittal translation of greater than 2mm.

Eighty one patients (39%) demonstrated at least one parameter beyond previously set standards for malreduction. Only one parameters was anomalous in 54 patients (26%), 18 patients (8%) had two positive parameters, while eight patients (4%) had three. One patient was asymmetrical in all measured parameters.

In this study there was no statistically significant asymmetry between ankles. However, 39% of native syndesmoses would be classified as malreduced on CT scan using previously studied malreduction limits. Current radiographic parameters are not sufficient to differentiate mild inherent anatomical asymmetry from malreduction of the syndesmosis.

Dual plating of the medial and lateral distal femur has been proposed to reduce angular malunion and hardware failure secondary to delayed union or nonunion. This strategy improves the strength and alignment of the construct, but it may compromise the vascularity of the distal femur paradoxically impairing healing. This study investigates the effect of dual plating versus single plating on the perfusion of the distal femur.

Ten matched pairs of fresh-frozen cadaveric lower extremities were assigned to either isolated lateral plating or dual plating of a single limb. The contralateral lower extremity was used as a matched control. A distal femoral locking plate was applied to the lateral side of ten legs using a standard sub-vastus approach. Five femurs had an additional 3.5mm reconstruction plate applied to the medial aspect of the distal femur using a medial sub-vastus approach.

The superficial femoral artery and the profunda femoris were cannulated at the level of the femoral head. Gadolinium MRI contrast solution (3:1 gadolinium to saline ration) was injected through the arterial cannula. High resolution fat-suppressed 3D gradient echo sequences were completed both with and without gadolinium contrast. Intra-osseous contributions were quantified within a standardized region of interest (ROI) using customized IDL 6.4 software (Exelis, Boulder, CO). Perfusion of the distal femur was assessed in six different zones. The signal intensity on MRI was then quantified in the distal femur and comparison was made between the experimental plated limb and the contralateral, control limb. Following completion of the MRI protocol, the specimens were injected with latex medium and the extra-osseous vasculature was dissected.

Quantitative MRI revealed that application of the lateral distal femoral locking plate reduced the perfusion of the distal femur by 21.7%. Within the dual plating group there was a reduction in perfusion by 24%. There was no significant difference in the perfusion between the isolated lateral plate and the dual plating groups. There were no regional differences in perfusion between the epiphyseal, metaphyseal or meta-diaphyseal regions.

Specimen dissection in both plating groups revealed complete destruction of any periosteal vessels that ran underneath either the medial or lateral plates. Multiple small vessels enter the posterior condyles off both superior medial and lateral geniculate arteries and were preserved in all specimens. Furthermore, there was retrograde flow to the distal most aspect of the condyles medially and laterally via the inferior geniculate arteries. The medial vascular pedicle was proximal to the medial plate in all the dual plated specimens and was not disrupted by the medial sub-vastus approach in any specimens.

Fixation of the distal femur via a lateral sub-vastus approach and application of a lateral locking plate results in a 21% reduction in perfusion to the distal femur. The addition of a medial 3.5mm reconstruction plate does not significantly compromise the vascularity of the distal femur. The majority of the vascular insult secondary to open reduction, internal fixation of the distal femur occurs with application of the lateral locking plate.

Introduction

The vascular anatomy of the femoral head and neck has been previously reported, with the primary blood supply attributed to the deep branch of the Medial Femoral Circumflex Artery (MFCA). This understanding has led to development of improved techniques for surgical hip dislocation for multiple intra-capsular hip procedures including Hip Resurfacing Arthroplasty (HRA). However, there is a lack of information in the literature on quantitative analysis of the contributions of the Lateral Femoral Circumflex Artery (LFCA) to femoral head and neck. Additionally, there is a lack of detailed descriptions in the literature of the anatomic course of the LFCA from its origin to its terminal branches.

In spite of extensive accounts describing the blood supply to the femoral head, the prediction of avascular necrosis is elusive. Current opinion emphasises the contributions of the superior retinacular artery but may not explain the clinical outcome in many situations, including intramedullary nailing of the femur and resurfacing of the hip. We considered that significant additional contribution to the vascularity of the femoral head may exist. A total of 14 fresh-frozen hips were dissected and the medial circumflex femoral artery was cannulated in the femoral triangle. On the test side, this vessel was ligated, with the femoral head receiving its blood supply from the inferior vincular artery alone. Gadolinium contrast-enhanced MRI was then performed simultaneously on both control and test specimens. Polyurethane was injected, and gross dissection of the specimens was performed to confirm the extraosseous anatomy and the injection of contrast. The inferior vincular artery was found in every specimen and had a significant contribution to the vascularity of the femoral head. The head was divided into four quadrants: medial (0), superior (1), lateral (2) and inferior (3). In our study specimens the inferior vincular artery contributed a mean of 56% (25% to 90%) of blood flow in quadrant 0, 34% (14% to 80%) of quadrant 1, 37% (18% to 48%) of quadrant 2 and 68% (20% to 98%) in quadrant 3. Extensive intra-osseous anastomoses existed between the superior retinacular arteries, the inferior vincular artery and the subfoveal plexus.

Aims: 1) to create a new and reproducible animal model to produce heterotopic ossification (HO) 2) to be able to exactly quantify the amount of HO using a microCT scan and 3) to prove the hypothesis that COX-2 inhibitors are efficacious in the prevention of HO. Methods: We developed a IACUC-approved Lewis rat model, in which the ventral side of the right femur was scraped to mechanically disrupt the periosteum. By clamping the vastus intermedius ischemic injury to the muscle was produced to enhance HO. Finally homologous bone marrow from a donor rat was placed on the anterior surface of the femur. Half of the study group (8 rats) received chow mixed with a COX-2 inhibitor, while the other half received normal chow. After 6 weeks the animals were sacrificed, the femurs removed and imaged by microCT. Grading of HO was based on the thickness of ectopic bone as evaluated in a blinded fashion by 3 independent observers. Results: All animals developed bilateral HO. Rats treated with COX-2 inhibitors developed significantly less ectopic bone than the control group rats. Conclusions: The results suggest that we have created a very reliable, reproducible model to form ectopic bone in rats. Using the microCT we can precisely quantify the amount of HO. We have been able to show that COX-2 inhibitors significantly decrease the amount of HO formation and are thus a good alternative to non-specific NSAIDs with their potential serious side effects on the gastrointestinal tract and on hemo-stastis.

Aims: The purpose of this study was to quantify the amount of cell viability and cartilaginous damage present in non-reparable human osteoarticular fragments removed at the time of acetabular fracture surgery. Material and Methods: The cases of 6 patients with comminuted fractures of the acetabulum were prospectively analyzed. Average age was 39 years, and none of them had evidence of preexisting hip pathology. Loose small osteoarticular fragments that were not reparable were microscopically analyzed to assess in-situ cell viability. Observations were divided into (i) depth of chondrocyte death from the articular surface, and (ii) structural matrix damage and cell death under regular histology. The depth of cell death was classiþed as mild between 1 and 15%, moderate from 15 to 30%, severe from 31 to 60% and total from 61 to 100%. Results: Five of the patients were classiþed as having only mild amount of chondrocyte death and one specimen had a moderate amount of chondrocyte death. The articular surface damage was mainly located on the superþcial zone of the cartilage. Discussion and conclusion: Most of the chondrocytes on small osteochondral fragments removed from displaced intraarticular acetabular fractures were still viable after having received a substantial amount of trauma.

Aims: To determine the results of Òbiologic þxationÒ with a minimally invasive plating technique using a newly designed low proþle ÒScallopÒ plate in the treatment of pilon fractures. Methods: 17 patients were treated between 1999 and 2001 for a tibial plafond with a newly designed ultra-slim plate. Eleven (65%) were high-energy injuries, two were open. Staged open reduction and þxation of the þbular fracture and application of an External Fixator was performed in 12 cases. As soon as the soft tissues and swelling allowed, the articular surface was reconstructed and anatomically reduced, if necessary through an small incision, and the articular block was þxed to the diaphysis using a medially placed, percutaneously introduced ßat Scallop plate. Time to healing and complications were evaluated. Quality of the results and outcome were graded using the Ankle-Hindfoot-Scale. Results: All patients went on to bony union at an average time of 14.1 weeks. There were no plate failures or loss of þxation/ reduction. Two superþcial wound-healing problems resolved with local wound care. At an average FU of 17 months eight patients (47%) had an excellent, seven (41%) a fair and two (12%) a poor result. The average AHS was 86.1. Conclusions: Based on these initial results, it appears that a minimally invasive surgical technique using a new low proþle plate can decrease soft tissue problems while leading to fracture healing and obtaining results comparable with other more recent series. We believe that this new ÒScallop PlateÒ is appropriate for the treatment of pilon fractures and should be used in conjunction with a staged procedure in the acute trauma setting.

Aims: Nonunions of the distal tibia are difþcult to treat due to the short distal segment, the proximity to the ankle joint and the fragile soft tissue envelope. Intramedullary nailing is an attractive solution as it avoids extensive soft tissue dissection and remains intraosseus, posing little problem for the soft tissues. The purpose of this study was to determine the efþcacy of reamed intramedullary nailing in the treatment of non-unions of the distal one-quarter of the tibia. Methods: Thirty-two patients with nonunions of the distal one-quarter of the tibia were treated by reamed, locked intramedullary nailing. Prior treatments included casting as well as intramedullary or extramedullary þxation techniques. No patient had signs of an active infection at the time of surgery. Time to union, correction of deformity and complications including infection and reoperation were examined. Results: Twenty-nine out of thirty-two patients achieved union at an average of 3.5 months after surgery. Of the remaining three, two patients united rapidly after dynamisation and one after exchange nailing. Deformity was corrected to a maximum of four degrees in all planes. Four patients had positive intraoperative culture, and only two required removal of the nail after achieving union to eradicate infection. There were no cases of chronic osteomyelitis after the procedure. Conclusions: Reamed, locked intramedullary nailing is a reliable and safe procedure in the treatment of nonunions in the distal one-quarter of the tibia. It allows for excellent correction of deformity, which is an essential component of the procedure.