Clinical usefulness of single photon emission tomography/computed tomography with stress analysis in early diagnoses of stem instability of noncemented hip arthroplasty.

OBJECTIVE: Hip pain arising from implant instability is generally caused by repetitive stress injury, which subsequently leads to induction or exacerbation of abnormal metabolism of bone around the implant. single photon emission tomography/computed tomography (SPECT-CT) has advantages in localizing areas of increased tracer uptake that reflects such abnormal bone metabolism. Therefore, we investigated whether the application of SPECT/CT with stress analysis can be an effective practice in evaluating the instability of stem in noncemented hip arthroplasty or not. METHOD: In total 16 patients were collected for unexplained painful hip arthroplasties. When physical examination and blood tests were unremarkable, radiographs were inconclusive and bone scan indicated increased scintigraphic uptake at the proximal part and at the tip of the stem; SPECT/CT was performed. Stem stability was assessed by measuring whether there was consistency between the increased scintigraphic uptake and the direction of the stress around the implant along with the location of the prosthesis. RESULT: Among the 16 symptomatic hips, 9 hips showed the stability of the stem, 3 hips showed the stem instability and 4 hips showed the acetabular loosening with the stem stability. With the application of SPECT/CT with stress analysis, 15 out of 16 (93.7%) cases were found to have the change in the diagnoses, and managements were implemented in 11 out of 16 (68.7%) cases. When comparing before and after SPECT/CT, there was no significant association in clinical diagnosis and management (Pearson chi- square test = 4.61 and 1.33, P = 0.33 and 0.25). CONCLUSION: SPECT/CT combined with stress analysis can be a useful tool in early diagnosis of stem instability and can assist surgeons in subsequent management and decision implementation when other radiographic imagings are inconclusive.

Treatment of Isolated Posterolateral Tibial Plateau Fracture with a Horizontal Belt Plate through the Anterolateral Supra-Fibular-Head Approach.

The posterolateral tibial plateau fracture was not easy to be exposed and fixed with usual techniques. The aim of this study was to investigate the biomechanical stability and clinical outcome of the isolated posterolateral tibial plateau fracture fixed with a single horizontal belt plate through the anterolateral supra-fibular-head approach. Fracture models were created by 18 synthetic tibias and fixed with three different fixation modes. Each group was fixed and tested on the loading machine, and final vertical displacement of the fragment was detected and calculated. Clinically, a retrospective analysis of 12 cases of posterolateral tibial plateau fracture from January 2013 to December 2017 was performed. There were 8 males and 4 females, aged 33-72 years, with an average age of 49.6 years. Isolated posterolateral tibial plateau fractures were identified according to preoperative X-ray and computed tomography scan. Through the modified anterolateral supra-fibular-head approach, the fracture was reduced and fixed by a prebending T-shaped distal radius plate and rafting screws, with bone substitute grafting or autogenous iliac bone implantation. Patients were followed up to a minimum one year of time period, and the outcome was evaluated clinically and radiologically. The biomechanical study shows that horizontal belt plate fixation for the isolated PL tibial plateau fracture can provide sufficient stability, allowing early knee functional exercise and partial weight bearing. For clinical case series, the average operation time in this group was 73.3 ± 10.2 mins (range: 55-90), and the average duration of hospitalization was 9.1 ± 3.3 days (range: 5-16). Patients were followed up for 12-24 months with an average of 16.5 months, and all patients achieved radiological fracture union after an average of 13.7 weeks. At one year after operation, the average knee score of the Hospital for Special Surgery (HSS) scale was 93.2 ± 4.2 points(range: 90-98), the average score of SMFA was 21.1 ± 5.6 points (range: 14-31), and the average knee range of motion (ROM) was 121.48° ± 8.88° (range: 105°-135°). There were 8 cases that were very satisfied and 3 cases that were satisfied with the operation. For an isolated posterolateral tibial plateau fracture, the supra-fibular-head approach can fully expose the fracture site; the horizontal belt plate fixation of the fracture is stable and reliable to allow for early-stage knee rehabilitation, and the outcome of medium-term clinical follow-up was satisfactory.

A new fluoroscopic view for evaluation of anteromedial cortex reduction quality during cephalomedullary nailing for intertrochanteric femur fractures: the 30° oblique tangential projection.

BACKGROUND: Anteromedial cortex-to-cortex reduction is a key parameter for stable reconstruction of the fracture fragments during the intertrochanteric fracture fixation. This paper introduces the oblique fluoroscopic projection as a novel method to evaluate the quality of anteromedial cortical apposition. METHODS: Three proximal femur specimens were marked with steel wires along five anatomic landmarks: Greater trochanter, Lesser trochanter, Intertrochanteric line, Anterolateral tubercle and the Anteromedial cortical line. After obtaining the standard femoral neck AP and lateral fluoroscopic images, the C-arm was rotated by every 5°increments until a clear tangential view of the antero-medial-inferior corner cortex was observed. 98 cases of intertrochanteric hip fractures were enrolled from April 2018 to October 2019. After fixation with the nails, the intra-operative anteromedial cortex reduction quality was evaluated from the AP, the true lateral, and the new anteromedial oblique fluoroscopic images. The fluoroscopic results were compared with the post-operative 3D-CT reconstruction images. RESULTS: The specimen study showed that internal rotation of the C-arm to approximately 30 ° can remove all the obscure shadows and clearly display the antero-medial-inferior cortical tangent line. Clinically,the positive, neutral and negative apposition of different cortices via intra-operative fluoroscopic images showed79, 19 and 0 cases of medial cortical apposition in AP views; 2, 68 and 28 cases of anterior cortices in lateral views;and 22, 51 and 25cases of anteromedial cortical apposition in oblique views respectively. The post-operative 3D-CT reconstruction images revealed that the final anteromedial cortical contact was noted in 62 cases (63.3%), and lost in 36 cases (36.7%). The overall coincidence rate between intra-operative fluoroscopy and post-operative 3D-CT was 63.3% (62/98) in AP view,79.6% (78/98) in lateral view, and 86.7% (85/98) in oblique view(p < 0.001). Negative cortical apposition in oblique view was highly predictive of a final loss of cortical support on 3D CT (24/25 cases, 96%).And non-negative cortical apposition in oblique view was highly associated with true cortical support on 3D CT images (61/73 cases, 83.6%) (p < 0.001). CONCLUSIONS: Besides the AP and lateral projections, an anteromedial oblique view of 30° certifies to be a very useful means for evaluation of the fracture reduction quality of anteromedial cortical apposition.