John Bottros

The Use of Navigation in Total Knee Arthroplasty for Patients With Extra-Articular Deformity ☆

Computer-assisted navigation for total knee arthroplasty provides high technology instrumentation that may improve the technique for restoring the normal lower limb mechanical axis. This study evaluated the use of computer-assisted navigation in 7 patients (9 total knee arthroplasties) with a radiographic femoral extra-articular deformity. Postoperatively, the mechanical axis deviated medially by a mean of 1.3 degrees +/- 0.9 degrees (range, -0.2 degrees to 2.5 degrees ). Early patient outcomes showed an increase in the average preoperative to postoperative Knee Society Scores (from 62 to 92, P < .05), function scores (from 52 to 83, P < .05), and range of motion (from 4 degrees -74 degrees to 0.6 degrees -98 degrees , P < .05). These results support the use of computer-assisted navigation as effective high technology instrumentation in recreating an acceptable mechanical axis in patients with distorted anatomical landmarks.

Mirels’ Rating for Humerus Lesions is Both Reproducible and Valid

AbstractMirels’ rating system is commonly used to predict risk of fracture in patients with metastatic bone lesions to long bones, but it has not been independently validated for use in humeral bone lesions. We asked whether this system was a valid and reproducible instrument for predicting impending pathologic fractures in the humerus. We presented 17 case histories and plain radiographs of 16 patients with humeral metastases through a web-based survey to 39 physicians with varying training and experience. Participants scored each case using Mirels’ criteria and provided a fracture prediction, which was compared with actual outcome in the subset of 12 patients with three fractures not treated prophylactically. Using Mirels’ definition of impending pathologic fracture (nine points or greater), the sensitivity and specificity for determining the likelihood of pathologic humeral fracture were 14.5% and 82.9%, respectively. When we used seven or more points as the definition of impending pathologic humeral fracture, sensitivity improved to 81% but specificity was reduced to 32%. Kappa analysis suggested moderate reproducibility across groups for prediction of pathologic fracture. The Mirels rating system for humeral lesions is reproducible and valid, but low specificity at acceptable sensitivity levels as reported remains a problem as for femoral lesions. Level of Evidence: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

A rapid recovery program after total hip arthroplasty

BackgroundEarly postoperative care of total hip arthroplasty (THA) has focused primarily on decreasing patient length of stay in the hospital while increasing independent function at discharge. This study analyzes how implementing a rapid recovery program affects length of stay and early postoperative pain control and function. MethodsA retrospective review of 103 patients who had THA (73 traditional and 30 using the rapid recovery program) was conducted between January 2005 and December 2007. ResultsPatients treated with the rapid recovery program had a decreased average length of stay in the hospital (P=0.02), improved walking distance (P=0.01) and lower visual analog scale pain ratings on the second postoperative day (P=0.01). Trends toward improved Harris Hip Scores as well as increased discharge home also were observed in the rapid recovery group. ConclusionsThis study reports data to support a more efficient and safe way to rehabilitate THA patients. The rapid recovery program described emphasizes the importance of a multidisciplinary team.

Impingement and stability of total hip arthroplasty versus femoral head resurfacing using a cadaveric robotics model

We identified and compared the impingent‐free range of motion (ROM) and subluxation potential for native hip, femoral head resurfacing (FHR), and total hip arthroplasty (THA). These constructs were also compared both with and without soft tissue to elucidate the role of the soft tissue. Five fresh‐frozen bilateral hip specimens were mounted to a six‐degree of freedom robotic manipulator. Under load‐control parameters, in vivo mechanics were recreated to evaluate impingement free ROM, and the subluxation potential in two “at risk” positions for native hip, FHR, and THA. Impingement‐free ROM of the skeletonized THA was greater than FHR for the anterior subluxation position. For skeletonized posterior subluxations, stability for THA and FHR constructs were similar, while a different pattern was observed for specimens with soft tissues intact. FHR constructs were more stable than THA constructs for both anterior and posterior subluxations. When the femoral neck is intact the joint has an earlier impingement profile placing the hip at risk for subluxation. However, FHR design was shown to be more stable than THA only when soft tissues were intact.

A robotic model of HIP dislocation potential: Total hip arthroplasty versus femoral head resurfacing

Hip dislocation often results from neck impingement and subsequent subluxation. Having a model to study impingent-free range of motion (ROM) and dislocation potential at the impingement postures can elucidate the contribution to joint stability of prosthetic design, component position, anatomical variables, and biomechanical factors. Much controversy surrounds the resurgence of femoral head resurfacing (FHR) and its biomechanical implications of retaining the femoral neck, particularly its head-neck ratio. We have developed a dynamic cadaveric robotics model that functions in real time under load-control parameters to recreate in vivo hip mechanics. This study specifically identifies and compares the impingent-free ROM and a stability index value that quantifies the dislocation potential in the native hip, femoral head resurfacing and total hip replacement (size 28, 36mm femoral heads).Copyright