Hidemi Kawaji

Pseudotumor and deep venous thrombosis due to crevice corrosion of the head-neck junction in metal-on-polyethylene total hip arthroplasty

After the implantation of metal-on-metal hip prostheses, pseudotumors or soft-tissue reactions—so-called adverse local tissue reactions (ALTRs)—have frequently been reported [1–7]. However, there are limited reports on the development of a pseudotumor due to crevice corrosion after insertion of a metal-on-polyethylene hip prosthesis. Here we describe a case of pseudotumor and deep venous thrombosis (DVT) causing persistent left hip pain as a result of crevice corrosion of the head–neck junction that required revision surgery in a metal-on-polyethylene hip prosthesis.

Influence of the Medial Knee Structures on Valgus and Rotatory Stability in Total Knee Arthroplasty

BACKGROUND Precise biomechanical knowledge of individual components of the MCL is critical for proper MCL release during TKA. This study was to define the influences of the deep MCL and the POL on valgus and rotatory stability in TKA using cadaveric knees. METHODS This study used six fresh-frozen cadaveric knees. All TKA procedures were performed using a cruciate-retaining TKA with a CT-free navigation system. We did a sequential sectioning on each knee, S1; femoral arthroplasty only, S2; medial half tibial resection with spacer, S3; anterior cruciate ligament cut, S4; tibial arthroplasty, S5; release of the dMCL, S6; release of the POL. The navigation system monitored motion after application of 10 N-m valgus loads and 5 N-m internal and external rotation torques to the tibia at 0°, 20°, 30°, 60°, and 90° of knee flexion for each sequence. RESULTS There were no significant differences in medial gaps. Internal rotation angles significantly increased after S2 at 0°, 20°, and 30°, and after S6 at 90° compared with those after S1. External rotation angles significantly increased after S3 at 0°, S4 at 60°, S5 at 0°, 30° and 90°, and after S6 at 30°, 60° compared with those after S1. CONCLUSION Significant increases of rotatory instability were seen on release of the dMCL, and then further increased after release of the POL. Surgical approach of retaining the dMCL and POL has a possibility to improve the outcome after primary TKA.

Split Fracture of the Posteromedial Tubercle of the Talus: Case Report and Proposed Classification System

We describe a rare case of a fracture of the medial tubercle of the posterior process of the talus in a 16-year-old male athlete who fell during basketball practice. The patient presented to our orthopedic clinic when pain and swelling had persisted despite 2 weeks of anti-inflammatory medication and rest. Computed tomography and magnetic resonance imaging scans revealed a fracture of the posteromedial tubercle of the talus and a small amount of retained fluid in the joint. Immobilization with a below-the-knee cast and non-weightbearing for 4 weeks, with a gradual return to full activity, was successful. At the 1-year follow-up evaluation, the patient expressed no complaints. Fracture of the posteromedial tubercle of the talus will usually result in a misdiagnosis or delayed diagnosis owing to the insidious onset of symptoms. We believe the present fracture configuration resulted from the vertical compression force that occurred on landing by posterior medial ankle impingement in plantarflexion-supination, modifying the conventional concept of the posteromedial tubercle fracture. We also present a suggested classification with a flowchart diagram.

Influence of Femoral Implant Alignment in Uncemented Total Hip Replacement Arthroplasty: Varus Insertion and Stress Shielding

BACKGROUND The influence of varus insertion of femoral implants in uncemented total hip replacement arthroplasty (THR) remains unclear. Thus, in this study, we retrospectively assessed the clinical impact of uncemented THR with femoral implants that were inserted in varus on the basis of radiological findings. MATERIALS AND METHODS The study participants included 89 patients who underwent uncemented THR for 106 joints and were followed-up for >3 years. From clinical records, we retrieved Japanese Orthopaedic Association (JOA) pain scores and the range of motion (ROM) of flexion and abduction both preoperatively and at the final follow-up. The presence of varus insertion of the femoral implant and stress shielding were also retrospectively reviewed from X-rays. We defined varus insertion of the femoral implant as the axis of the femoral implant that was inclined to the femoral shaft by 2° or more. Stress shielding was judged in accordance with Enghs classification system. RESULTS Of the 106 joints, varus insertion was observed in 40 (37.3%) (the varus group) but not in 66 (62.3%) (the non-varus group). The JOA pain score significantly improved in both groups; however, there were no significant differences between the groups. Although ROM improved in both groups, there were no significant differences between the groups. The appearance rate of stress shielding of ≥third degree in the varus group was significantly greater than that in the non-varus group. CONCLUSION These results revealed that varus insertion of femoral implants had no influence on short- to mid-term clinical outcomes because the pain score and ROM significantly improved in both the varus and non-varus groups. However, high rates of severe stress shielding appeared with varus insertion of femoral implants, suggesting an influence on long-term clinical outcomes.