Stress-Induced, Aseptic Osteolysis of the Mid-Tibia in a Revision Hinged Total Knee Arthroplasty Mimicking Infection.

In this report, we present the case of an 80-year-old female with pain located over the tip of her cemented tibial stem in a revision hinge total knee arthroplasty with localized osteolysis that looked suspicious for infection. A thorough workup was negative for infection. We postulate that the osteolysis at the end of her tibial stem was initiated by a modulus of elasticity mismatch at the stem tip, which generated a focal area of increased sagittal bone bending and microparticle generation. She was treated with lesional exploration, debridement, synthetic bone grafting, and tibial plating to distribute stress loads away from the tibial stem tip. Histologic analysis identified no organisms or neoplasm. Her pain ultimately resolved, and the patient returned to her customary activities.

Modified hybrid cementing technique reduces stem tip pain and improves patient's satisfaction after revision total knee arthroplasty.

BACKGROUND: There have been no studies comparing patient-reported outcome measures including end-of-stem tip pain and patient satisfaction based on the use of cementing techniques in revision total knee arthroplasty (TKA). The purpose of this study was to compare end-of-stem tip pain and PROMs with hybrid and modified hybrid cementing techniques in revision TKAs. METHOD: Sixty-two cases of revision TKA performed by a single surgeon were divided into two groups based on the cementing technique with a minimum follow-up of 2 years. Two types of cementing technique for femoral and tibial stems were used as follows: (1) a hybrid cementing technique (33 cases), in which cement was applied immediately distal to the modular junction of the stem and the component while the distal stem was press-fitted into the diaphysis without using cement; and (2) a modified hybrid cementing technique (29 cases), in which cement was applied to the tip of femoral and tibial stems. The thigh and shin were assessed for the end-of-stem tip pain. Patient satisfaction was evaluated based on the satisfaction items of New Knee Society Score. RESULTS: Modified hybrid cementing significantly lowered the percentage of patients manifesting shin pain (3.4% vs. 24.2%, p = 0.029). Patients treated with the modified hybrid cementing technique showed a higher satisfaction rate (p = 0.003). Multivariate logistic regression analysis showed an increase in the odds of satisfaction 32.686-fold (p = 0.004) in patients without pain at the end-of-stem tip in the shin and 9.261-fold (p = 0.027) in patients treated with the modified hybrid cementing technique. CONCLUSION: The modified hybrid cementing technique for fixation of long-stem in revision TKAs reduced the end-of-stem tip pain in the shin, leading to significantly higher satisfaction compared with the hybrid cementing technique after revision TKA. LEVEL OF EVIDENCE: Level III.

Cortical Strut Graft for Enigmatic Thigh Pain in Uncemented Total Hip Replacement.

Aims Enigmatic thigh pain in uncemented femoral components of a total hip replacement can be severe and disabling. Treatment can be conservative or surgical with cortical strut graft or revision of the femoral stem. Cortical strut grafting may offer good results with reduced morbidity. The aim of this study was to report the functional and radiographic outcomes of four patients with enigmatic thigh pain treated with cortical strut allograft. Materials and Methods Between 2016 and 2018, four women underwent cortical strut allografting at two centres. All patients had an uncemented, proximally porous S-ROM femoral implant (DePuy, Warsaw, In, USA). All other causes of anterolateral thigh pain were excluded. The mean age was 36.7 years (range: 29-51 years). Patients were followed up for a minimum of 14 months (range: 14-38 months). The University of California, Los Angles (UCLA) activity score, pain scores, complications, and radiographs at six weeks, three months, six months, nine months and one year were recorded. Results Mean UCLA activity scores increased from 3.2 (range: 2-4) to 6.2 (range: 6-7) post-operatively. Radiologically, all four patients had complete osseointegration of their strut grafts. Pain scores decreased at six weeks and at six months. One deep venous thrombosis occurred. One patient experienced recurrence of anterolateral thigh pain 26 months post-strut graft, which resolved with protected weight-bearing and analgesia for three months. Conclusions In uncemented femoral prostheses, cortical strut grafting to treat enigmatic thigh pain can reduce symptoms and increase activity without the need to revise a well-fixed femoral stem. We add to the growing body of evidence that this can be a successful surgical technique.

The Biomechanical Effect of Stem Design and Methods of Fixation in Revision Total Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: This study examined the effect of the stem design and method of fixation on biomechanical features around a stem tip in revision total knee arthroplasty using finite analysis. MATERIALS AND METHODS: A 3D Finite element model was reconstructed for a CT scan of the normal tibia from a 26 year old male and the CAD model of total knee arthroplasty revision was developed. The design change in the stem such as the length, diameter, slot, press fit and coefficient of friction was performed. The contact pressure, von-Meises stress around the stem and the micromotion were evaluated. RESULTS: A longer length and larger diameter press fit stem significantly increased the contact pressure and stress at the end of stem. The distal slot reduces the contact pressure and stress at the end of stem. Less displacement between the tibial component and bone was noted in the increased coefficient of friction. CONCLUSION: A stem with shorter length sufficient to engage proximal diaphysis, a closer diameter of the proximal canal and a minimal press fit can be used to reduce the contact pressure and stress if the patient's surgical anatomy such as bone loss and quality is tolerable in revision total knee arthroplasty.