Wear debris released by hip prosthesis analysed by microcomputed tomography.

Total hip arthroplasty uses commercial devices that combine different types of biomaterials. Among them, metals, ceramics and metal oxides can be used either in the prosthesis itself or in the cement used to anchor them in the bone. Over time, all of these materials can wear out and release particles that accumulate in the periprosthetic tissues or can migrate away. We used histology blocks from 15 patients (5 titanium metallosis, 5 alumina prostheses, 5 with altered methacrylic cement) to perform a microCT study and compare it with conventional histology data. An EDS-SEM analysis was done to characterise the atomic nature of the materials involved. A morphometric analysis was also performed in 3D to count the particles and assess their density and size. The metallic particles appeared to be the largest and the ceramic particles the finest. However, microCT could not reveal the wear particles of radiolucent biomaterials such as polyethylene and the very fine zirconia particles from cement fragmentation. MicroCT analysis can reveal the extent of the accumulation of these debris in the periprosthetic tissues. LAYOUT DESCRIPTION: Hip prostheses progressively degrade in the body by releasing wear debris. They accumulate in the periprosthetic tissues. Microcomputed tomography was used to image three types of radio-opaque wear debris: metal, ceramic and zirconia used in the bone cements.

Reconstruction of large diaphyseal bone defect by simplified bone transport over nail technique: A 7-case series.

Reconstruction of large diaphyseal bone defect is complex and the complications rate is high. This study aimed to assess a simplified technique of segmental bone transport by monorail external fixator over an intramedullary nail.A prospective study included 7 patients: 2 femoral and 5 tibial defects. Mean age was 31years (range: 16-61years). Mean follow-up was 62 months (range: 46-84months). Defects were post-traumatic, with a mean length of 7.2cm (range: 4 to 9.5cm). For 3 patients, reconstruction followed primary failure. In 4 cases, a covering flap was necessary. Transport used an external fixator guided by an intramedullary nail, at a rate of 1mm per day. One pin was implanted on either side of the distraction zone. The external fixator was removed 1 month after bone contact at the docking site. Mean bone transport time was 11 weeks (range: 7-15 weeks). Mean external fixation time was 5.1months (range: 3.5 to 8months). Full weight-bearing was allowed 5.7months (range: 3.5-13months) after initiation of transport. In one patient, a pin had to be repositioned. In 3 patients, the transported segment re-ascended after external fixatorablation, requiring repeat external fixation and resumption of transport. There was just 1 case of superficial pin infection. Reconstruction quality was considered "excellent" on the Paley-Marr criteria in 6 cases. The present technique provided excellent reconstruction quality in 6 of the 7 cases. External fixation time was shorter and resumption of weight-bearing earlier than with other reconstruction techniques, notably including bone autograft, vascularized bone graft or the induced membrane technique. Nailing facilitated control of limb axis and length. The complications rate was 50%, comparable to other techniques. This study raises the question of systematic internal fixation of the docking site, to avoid any mobilization of the transported segment. The bone quality, axial control and rapidity shown by the present technique make it well-adapted to reconstruction of diaphyseal bone defect. LEVEL OF EVIDENCE: Four-case series.

Is radiographic measurement of distal femoral torsion reliable?

BACKGROUND: Distal femur torsion (DFT) is a crucial parameter in knee replacement surgery. The reference standard for measuring DFT is posterior condylar angle (PCA) measurement using computed tomography (CT). The objective of this study was to assess the feasibility and reliability of a radiographic PCA measurement method. MATERIALS AND METHODS: We studied 125 osteoarthritic knees in 79 patients (42 women and 37 men) with a mean age of 71.6 ± 8.8 years (range 47 to 86 years); 32 knees were aligned, 85 in varus, and eight in valgus. DFT was measured on an antero-posterior (AP) radiograph of the knee in 90° of flexion (known as the seated AP view). The PCA was defined as the angle subtended by the tangent to the posterior condyles and the transepicondylar axis (anatomic PCA [aPCA]) or the line connecting the lateral epicondyle to the medial sulcus (surgical PCA [sPCA]). The PCA was conventionally recorded as positive in the event of external torsion and negative in the event of internal torsion. PCA measurements were performed three times by each of five observers to allow assessments of inter-observer and test-retest reliabilities. RESULTS: aPCA was consistently negative (mean, -6.1 ± 1.6°) (range, 0 to -10°); inter-observer and test-retest reliability were satisfactory (0.54

Isolated interfragmentary compression for nonunion of humeral shaft fractures initially treated by nailing: A preliminary report of seven cases.

INTRODUCTION: Plating with bone grafting is considered the gold standard treatment for nonunion of humeral shaft fractures. However, this complex procedure involves multiple risks. The aim of this study is to evaluate an alternative treatment using isolated axial interfragmentary compression for the dynamisation of humeral shaft nonunion after retrograde locked nailing. MATERIALS AND METHODS: Between January 2000 and May 2009, 124 humeral shaft fractures were treated in our trauma department with retrograde locked nailing using the unreamed humeral nail (UHN(®), Synthes, Paoli, PA, USA). Nonunion occurred in seven patients (5.6%) - five females and two males, mean age 44 years (range: 17-73 years). The nonunion was treated by applying isolated secondary interfragmentary compression. Mean follow-up was 43 months (range: 8-74 months). The Rommens score and the disabilities of the arm, shoulder and hand (DASH) score were used to evaluate the global functioning of the upper limb. RESULTS: The compression procedure was successful in all seven cases. In each case, the union occurred without any complications in 3-5 months. The mean DASH score was 25/100 (range: 8.3-60.8/100). The Rommens score was judged excellent for five of the seven patients but two were rated moderate. One of these suffered from complex regional pain syndrome type II since the fracture, and another developed a stiff shoulder 6 months after trauma. CONCLUSION: Isolated secondary interfragmentary compression appears to be a simple and successful procedure in cases of humeral nonunion.

The concept of locking plates.

After a short historical review of locking bone plates since their inception more than a century ago to the success of the concept less than 15 years ago with today's plates, the authors present the main locking mechanisms in use. In the two broad categories - plates with fixed angulation and those with variable angulation - the screw head is locked in the plate with a locknut by screwing in a threaded chamber on the plate or by screwing through an adapted ring. The authors then provide a concrete explanation, based on simple mechanical models, of the fundamental differences between conventional bone plates and locking plates and why a locking screw system presents greater resistance at disassembly, detailing the role played by the position and number of screws. The advantages of epiphyseal fixation are then discussed, including in cases of mediocre-quality bone. For teaching purposes, the authors also present assembly with an apple fixed with five locking screws withstanding a 47-kg axial load with no resulting disassembly. The principles of plate placement are detailed for both the epiphysis and diaphysis, including the number and position of screws and respect of the soft tissues, with the greatest success assured by the minimally invasive and even percutaneous techniques. The authors then present the advantages of locking plates in fixation of periprosthetic fractures where conventional osteosynthesis often encounters limited success. Based on simplified theoretical cases, the economic impact in France of this type of implant is discussed, showing that on average it accounts for less than 10% of the overall cost of this pathology to society. Finally, the possible problems of material ablation are discussed as well as the means to remediate these problems.

Total knee arthroplasty with limitations of flexion.

UNLABELLED: Does total knee arthroplasty (TKA) increase mobility in stiff knees, where flexion is restricted due to degenerative changes associated with osteoarthritis, inflammatory disease, hemophilia, or post-traumatic sequelae also affecting soft tissue? The results of one hundred twenty eight TKA from five specialized centers were retrospectively reviewed. Only knees with pre-operative flexion less than 90 degrees were included. Forty six of these also had severe flexion contracture (>20 degrees). As a result of the arthroplasty, the flexion increased by 23+/-17 degrees in group 1 (stiff flexion only, 82 cases), and by 17+/-15 degrees in group 2 (combined stiffness), in which the total range of motion (ROM) increased by 39+/-21 degrees. Improvements in mobility were greater in the cases with severe pre-operative stiffness. One-year functional results did not correlate with final flexion. Flexion at last follow-up did not depend on pre-operative flexion; however, in group 2, final postoperative ROM did correlate with pre-operative ROM. Complications concerned mainly those cases with severe stiffness, in which extensive quadriceps release was performed (two cases of skin necrosis, one infection and one rupture of the patellar tendon), or the patients of group 2 (one skin necrosis, two femoral fractures, one infection and one sciatic nerve palsy). Hemophilia was a factor of poor prognosis. Overall, TKA provided significant flexion gain. It often required tibial tuberosity osteotomy, to improve exposure and prevent injury to the extensor mechanism. Extensive quadriceps release should be reserved to post-traumatic cases with intact skin and no recent infection. TYPE OF STUDY: level 4 retrospective.

Total knee arthroplasty in patients with greater than 20 degrees flexion contracture.

UNLABELLED: Does total knee arthroplasty (TKA) correct the flexion contracture in knee stiffness associated with osteoarthritis, inflammatory disease, hemophilia or post-traumatic sequelae? The results of 107 TKAs from five specialized centers were retrospectively reviewed. Only knees with greater than or equal to 20 degrees flexion contracture on extension were included, 46 of which also had less than 90 degrees flexion. As a result of the arthroplasty, extension increased by 20+/-6 degrees in group 1 (flexion contracture only, n=61), and by 22+/-11 degrees in group 2 (combined stiffness, n=46), in which the total range of motion increased of 39+/-21 degrees. Overall, mean residual flexion contracture was 7+/-7 degrees. Improvements in mobility were greater in the cases with severe preoperative stiffness. One-year functional results correlated with final residual flexion contracture. Mobility at last follow-up did not depend on preoperative mobility, except in group 2, in which the final postoperative range of motion (ROM) correlated with preoperative ROM. Hemophilia was a factor of poor prognosis. Recovering full extension at end of surgery is mandatory, by first releasing the posterior capsule and the collateral ligaments from their osteophytes, and secondly by extending the distal femoral cut where necessary. TYPE OF STUDY: Level 4 retrospective.