Surgically oriented measurements for three-dimensional characterization of tunnel placement in anterior cruciate ligament reconstruction.

OBJECTIVE: To develop and evaluate the feasibility and reliability of an alternative three-dimensional (3D) measurement system capable of characterizing tunnel position and orientation in ACL reconstructed knees. METHODS: We developed a surgically oriented 3D measurement system for characterizing femoral and tibial drill tunnels from ACL reconstructions. This is accomplished by simulating the positioning of the drill bit originally used to create the tunnels within the bone, which allows for angular and spatial descriptions along defined axes that are established with respect to previously described anatomic landmarks and radiographic views. Computer-generated digital phantoms composed of simplified geometries were used to verify proper calculation of angular and spatial measurements. We also evaluated the inter-observer reliability of the measurements using 10 surfaces generated from cadaveric knees in which ACL tunnels were drilled. The reliability of the measurements was evaluated by intraclass correlation coefficients. RESULTS: The digital phantom evaluation verified the measurement methods by computing angular and spatial values that matched the known values in all cases. The intraclass correlation coefficient was calculated for four users and was found to range from 0.95 to 0.99 for the femoral and tibial measurements, demonstrating near-perfect agreement. CONCLUSIONS: The characterization of ACL tunnels has historically concentrated on two-dimensional (2D) measurements; however, it can be difficult to define ACL tunnel placement using 2D methods. We have presented novel techniques for defining graft tunnel placement from 3D surface representations of the ACL reconstructed knee. These measurements provide exact tunnel location spatially and along axes that offer the potential to comparatively analyze ACL reconstructions post-operatively using advanced imaging. These methods are reliable, and have been demonstrated to be applicable to multiple single-bundle techniques for ACL reconstruction.

Reliability of early postoperative radiographic assessment of tunnel placement after anterior cruciate ligament reconstruction.

PURPOSE: To evaluate the interobserver and intraobserver reliability of radiographic assessment of tunnel placement in anterior cruciate ligament reconstruction. METHODS: Seven sports fellowship-trained orthopaedic surgeons in the Multicenter Orthopaedic Outcomes Network (MOON) group participated in the study. We prospectively enrolled 54 consecutive patients after primary anterior cruciate ligament reconstruction. Postoperative plain radiographs were obtained including a full-extension anteroposterior view of the knee, a lateral view of the knee in full extension, and a notch view at 45° of flexion (Rosenberg view). Three blinded reviewers performed 8 different radiographic measurements including those of Harner and Aglietti/Jonsson. Intraclass correlation coefficients were used to determine reliability of the measurements. Intrarater reliability was assessed by repeated measurements of a subset of 20 patient images from 1 institution, and inter-rater reliability was assessed by use of all 54 sets of films from a total of 4 institutions. RESULTS: Intraobserver reliability for femoral measures ranged from none to substantial, with notch height having the worst results. Intraobserver reliability was moderate to almost perfect for tibial measures. Interobserver reliability ranged from slight to moderate for femoral measures. The Harner method for determining tunnel depth was more reliable than the Aglietti/Jonsson method. Interobserver reliability for tibial measures ranged from fair to substantial. The presence of metal interference screws did not improve reliability of measurements. CONCLUSIONS: Postoperative radiographs are easily obtained, but our results show that radiographic measurements are of quite variable reliability, with most of the results falling into the fair to moderate categories.

Metacarpophalangeal joint synovial osteochondromatosis: a case report.

We describe a case of primary articular synovial chondromatosis in a metacarpophalangeal (MCP) joint of a 48-year-old male. The patient initially presented with MCP joint swelling and pain with normal plain radiographs. Following a fourteen month course of conservative management, surgical debridement of the joint revealed multiple loose bodies consistent with primary articular synovial chondromatosis. Though synovial chondromatosis rarely occurs in hand joints, the diagnosis should be considered in cases of metacarpophalangeal pain when common etiologies have been excluded.

Interleukin-1 modulates periprosthetic tissue formation in an intramedullary model of particle-induced inflammation.

UNLABELLED: Interleukin-1 (IL-1) is a proinflammatory cytokine that has been implicated in wear-debris associated total joint replacement failure. We hypothesized that the absence of the IL-1 type-1 receptor would mitigate the inflammatory response to titanium particles and decrease periprosthetic inflammatory tissue in a murine intramedullary rod model. METHODS: An intramedullary rod with and without commercially pure titanium particles was placed in the femora of 24 wild type mice (WT) and 24 mice lacking a functional type-1 receptor to IL-1. Femora were analyzed histologically and by ELISA of organ culture explant supernatants. RESULTS: The presence of titanium particles in WT mice stimulated increased expression of interleukin-6 (IL-6) and macrophage chemoattractant protein-1 (MCP-1) relative to rod only controls. In contrast, IL-6 and MCP-1 expression were diminished in IL-1r1-KO mice exposed to titanium particles. Additionally, the formation of a periprosthetic fibro-inflammatory membrane in IL-1r1-KO mice was blunted at 2 weeks when compared to that in wild-type mice. Inflammatory changes and the quality of periprosthetic bone of IL-1r1-KO mice was similar to WT mice in response to titanium particles. CONCLUSIONS: These results implicate IL-1 as an important modulator in the local inflammatory response to intramedullary titanium particles. MCP-1 appears to be significantly modulated in IL-1r1-KO mice in response to titanium particles. This may be responsible, in part, for the diminished periprosthetic membrane observed in IL-1r1-KO mice at 2 weeks. Expansion of this murine model of intramedullary particle-induced inflammation to other gene targets may contribute to a more mechanistic understanding of wear-debris associated prosthesis failure.

Proinflammatory mediator expression in a novel murine model of titanium-particle-induced intramedullary inflammation.

Wear debris from total joint replacement prostheses is implicated in periprosthetic osteolysis and implant loosening. The pathophysiology of this biological process remains unclear. Animal models of particle-induced osteolysis have proven useful in the study of specific tissue responses to wear debris. However, existing in vivo murine models of particle-mediated inflammation do not permit analysis of cortical bone degradation. This study describes a murine model of particle disease using an intramedullary rod in the mouse femur to parallel the clinical situation. The model consists of placing a 10-mm-long Kirschner wire retrograde in both femurs of C57b1/6 male mice via a medial parapatellar arthrotomy. Phagocytosable titanium particles were also implanted unilaterally to replicate generation of wear debris. Mice were sacrificed at 2, 10, and 26 weeks and whole femurs were cultured for 72 h. Levels of interleukin-6, monocyte chemotactic protein-1, and macrophage colony stimulating factor were assayed by ELISA. Transverse histological sections, at the level of the implant, were taken and stained with hematoxylin and eosin (H&E). Results demonstrated increased expression of proinflammatory mediators at 2 weeks in femora with rod and particles compared to femora with rods alone. Destruction of the endosteum was evident at 2, 10, and 26 weeks in the femora with titanium. This novel murine model of particle-induced intramedullary inflammation may facilitate cost-effective genetic studies and offers investigators a simple, clinically relevant intramedullary model to readily examine the pathogenesis of particle-mediated periprosthetic osteolysis.