Use of a Modified Rep Model in Primary Joint Arthroplasty: Lessons Learned.

Orthopedic implant device sales representatives ("reps") can provide intraoperative guidance based on their product knowledge, as part of their many responsibilities. However, for experienced high-volume arthroplasty surgeons, a representative may not be required in the room for most primary total knee arthroplasty (TKA) procedures. The goal of this study was to describe the authors' experience with a modified rep model for primary TKA. Between January and December 2017, a total of 100 unilateral primary TKAs were performed with a modified rep model and compared with 100 primary TKAs that were performed before this protocol. The authors adopted 2 additional initiatives to institute this protocol safely: (1) improved education of operating room staff and allocation of responsibilities; and (2) reengineering of the existing surgical trays. No perioperative complications, including readmission, periprosthetic fracture, or infection, occurred in either group. In addition, no difference was found in mean length of stay between the modified rep and conventional cohorts (2.2 and 2.4 days, respectively; P=.49). Mean operating room time was less with the modified rep cohort (102.1 vs 117.8 minutes; P<.001), as was total instrument turnover time in the operating room (13.9 vs 29.7 minutes; P<.0001) and in central sterilization (59.4 vs 126.8 minutes; P<.001). No errors occurred with implant accuracy or trays, and there was no need to change the type of implant with the modified rep model, compared with 6% of trays requiring additional sterilization with the conventional model. The negotiated implant cost with the modified rep model was approximately $2000 less than that for the conventional group. This study found that the modified rep model for primary TKA is safe and has the potential for substantial cost savings. [Orthopedics. 2020;43(6):e538-e542.].

Customized Knee Articulating Cement Spacer with Stem Extension for Treatment of Chronic Periprosthetic Joint Infection.

INTRODUCTION: Choice of articulating spacer in selected Methicillin-resistant Staphylococcus aureus (MRSA) patients with instability that do not qualify for a second-stage revision (i.e., due to significant co-morbidities, multiple persistent infections, open wound ulcers) is challenging. To avoid a recurrent biofilm when using a cruciate-retaining (Cr/Cb) femoral implant, we have utilized a polymer femoral implant and constraint all-polyethylene (all-poly) tibia with stem extensions as a permanent spacer. MATERIALS AND METHODS: After removal of prior implants and final debridement, appropriate-sized trial femur and proper thickness all-poly tibia are selected. Two chest tubes are loaded with cement with a delivery gun to make the extension rods. A Steinmann pin is inserted into the stem of the tibial insert. The components are inserted and the knee is reduced, then flexion and extension gaps are assessed. Small adjustments can be made to fill the gaps with extra cement. If there is collateral insufficiency, a constrained polyethylene (poly) can be used with the extension rod. An appropriate antibiotic is used based on the final culture, sensitivity, and availability in powder form. RESULTS: This technique has been performed on 32 MRSA prosthetic joint infection (PJI) cases, followed for a minimum of nine months (nine months to three years). The mean final range of motion was 70 ± 15 degrees (30-110 degrees). Final radiographs do not show any sign of subsidence, loosening, or failure of the spacer. Rate of eradication of infection was 97% in the remaining 31 cases. One patient required amputation due to lack of wound coverage. CONCLUSION: Custom-made articulating spacer using all-poly tibia and a trial femur with stem extension can provide reproducible outcomes in treating PJI while maintaining mobility.

Piriformis-Sparing Technique in Total Hip Arthroplasty with Posterolateral Approach.

INTRODUCTION: Hip dislocation is a devastating complication after total hip arthroplasty (THA), which is slightly higher when using the traditional posterior approach. The piriformis tendon is the most important dynamic posterior stabilizing structure. The piriformis-sparing technique provides a reproducible method for THA, greatly reducing the dislocation rate. MATERIALS AND METHODS: After exposure and identifying piriformis, the inferior border of the piriformis is released from the short rotators and capsule with a BOVIE® (Symmetry Surgical, Inc, Nashville, Tennessee). This dissection is continued to the lesser trochanter as one sleeve and then tagged. The anterior/inferior capsule is released with a BOVIE® from the femur to aid in acetabular exposure. The femur is roughly placed in 30° of adduction, 70° of flexion, and slight internal rotation. An anterior retractor is used to displace the proximal femur anteriorly and superiorly. The reamer is placed inside the acetabulum through the inferior approach. Next, the acetabulum is progressively reamed to the appropriate size and depth, and the final component is placed in proper anteversion and abduction angles based on preoperative functional assessment. After insertion of final components and final hip reduction, the interval beneath the piriformis tendon and superior portion of the capsule is repaired with ETHIBOND® sutures (Johnson & Johnson Inc., New Brunswick, New Jersey). Then, two tunnels in the proximal femur with a 2.7mm drill bit is made and posterior capsule and short rotators are secured through these tunnels. RESULTS: This technique was used in 150 THAs with a minimum follow up of six months and a mean of 1.2 years ± 1.5 years. There was no dislocation at final follow up. The mean anteversion and abduction was 23 ± 2.7 and 42 ± 3.1, respectively. CONCLUSION: Preserving the piriformis tendon may cause less visualization of the superior portion of the acetabulum. However, the anterior/inferior capsular release, and proper placement of the femur with flexion, internal rotation, and adduction, makes it possible to achieve highly reproducible results.