One-stage versus two-stage prosthesis replacement for prosthetic knee infections.

INTRODUCTION: Periprosthetic knee infection is a severe complication. Confirmed criteria are lacking to choose between one-stage or two-stage prosthesis replacement to treat the infection. The one-stage replacement could lead to a satisfactory control of the infection and to better functional results. METHOD: Retrospective study conducted between January 1, 2009 and December 31, 2014. The objectives of this study were to compare the infection outcome and functional results between the one-stage and two-stage replacement procedures. Functional results were evaluated using the IKS score, KOOS score, and SF-12 quality of life score. RESULTS: Forty-one patients underwent a two-stage replacement procedure and 21 patients a one-stage replacement. The average follow-up was 22 months after surgery. The infection was cured in 78% of patients who underwent a two-stage replacement and 90% of patients who underwent a one-stage replacement (P=0.3). The flexion range of motion was significantly better in the one-stage group than in the two-stage group (P=0.04). Results of the IKS score and of the KOOS score were better in the one-stage group. No difference was observed for the SF-12 score. CONCLUSION: The one-stage replacement procedure for periprosthetic knee infection was associated with a similar healing frequency as the two-stage replacement procedure, and with better knee function.

EOS-based cup navigation: Randomised controlled trial in 78 total hip arthroplasties.

BACKGROUND: Minimising the risk of cup implantation outside the safe zone is among the objectives of navigation during total hip arthroplasty (THA). However, given the technical challenges raised by navigation when the patient is lying on the side, many surgeons still use the freehand technique. We conducted a randomised controlled trial to evaluate the new navigation system NAVEOS in the iliac plane, which is easily identified in the lateral decubitus position, with the objective of determining whether NAVEOS navigation decreased the frequency of cup implantation outside the safe zone compared to freehand cup positioning, without increasing the operative time or the frequency of complications. HYPOTHESIS: NAVEOS navigation decreases the frequency of cup positioning outside the safe zone compared to freehand positioning. MATERIAL AND METHODS: This randomised controlled trial compared cup positioning using NAVEOS navigation versus the freehand technique in patients undergoing primary THA. The safe zone was defined according to Lewinnek as 15±10° of radiological anteversion and 40±10° of radiological inclination. Cup position parameters were measured on computed tomography images obtained 3months after THA. The images were read by two independent observers who were blinded to group assignment. The primary evaluation criterion was cup position within the safe zone. RESULTS: A 1:1 randomisation scheme was used to assign 78 patients (mean age, 68years; age range, 44-91years) to NAVEOS navigation or freehand cup positioning. The two groups were comparable for age, gender distribution, body mass index, and preoperative functional scores. In the NAVEOS group, navigation was discontinued prematurely in 6 patients, because of technical difficulties (n=2) or a marked discrepancy with clinical findings (n=4); however, the intention-to-treat approach was used for the analysis. The proportion of cups in the safe zone was 67% (28/39) in the NAVEOS group and 38% (17/39) in the freehand group (P=0.012). Anteversion was within the 5-25° range for 72% (28/39) cups in the NAVEOS group and 46% (18/39) in the freehand group (P=0.021). Inclination was within the 30-50° range for 95% (37/39) of cups with NAVEOS navigation and 85% (33/39) with freehand positioning (P=0.135). The odds ratio for cup implantation outside the safe zone was significantly lower with NAVEOS compared to freehand positioning (0.54; 95% confidence interval, 0.31-0.91). Mean operative time was 74 (range, 45-115) minutes with NAVEOS navigation and 70 (range, 40-105) minutes with freehand positioning (P=0.382). Complications consisted of 1 case each of anterior dislocation and infection, both in the freehand group. DISCUSSION: Compared to freehand positioning, NAVEOS navigation significantly lowered the risk of cup positioning outside the safe zone, chiefly via improved achievement of the anteversion target. NAVEOS was not associated with increases in operative time or morbidity. LEVEL OF EVIDENCE: II, randomised controlled trial with limited statistical power.

Change in acetabular version after lumbar pedicle subtraction osteotomy to correct post-operative flat back: EOS® measurements of 38 acetabula.

BACKGROUND: Abnormalities in acetabular orientation can promote the development of hip osteoarthritis, femoro-acetabular impingement, or even acetabular cup malposition. The objective of the present study was to determine whether pedicle substraction osteotomy (PSO) to correct sagittal spinal imbalance affected acetabular orientation. HYPOTHESIS: PSO performed to correct sagittal spinal imbalance affects acetabular orientation by changing the pelvic parameters. MATERIALS AND METHODS: This was a descriptive study in which two observers measured the acetabular parameters on both sides in 19 patients (38 acetabula) before and after PSO for post-operative flat-back syndrome. Mean time from PSO to post-operative measurements was 19months. Measurements were taken twice at a 2-week interval, on standing images obtained using the EOS(®) imaging system and sterEOS(®) software to obtain 3D reconstructions of synchronised 2D images. Acetabular anteversion and inclination were measured relative to the vertical plane. Mean pre-PSO and post-PSO values were compared using the paired t-test, and P values lower than 0.05 were considered significant. To assess inter-observer and intra-observer reproducibility, we computed the intra-class correlation coefficients (ICCs). RESULTS: The measurements showed significant acetabular retroversion after PSO, of 7.6° on the right and 6.5° on the left (P<0.001). Acetabular inclination diminished significantly, by 4.5° on the right and 2.5° on the left (P<0.01). Inclination of the anterior pelvic plane decreased by 8.4° (P<0.01). Pelvic incidence was unchanged, whereas sacral slope increased by 10.5° (P<0.001) and pelvic tilt decreased by 10.9° (P<0.001). The ICC was 0.98 for both inter-observer and intra-observer reproducibility. CONCLUSION: Changing the sagittal spinal alignment modifies both the pelvic and the acetabular parameters. PSO significantly increases sacral slope, thus inducing anterior pelvic tilt with significant acetabular retroversion. The measurements obtained using sterEOS(®) showed good inter-observer and intra-observer reproducibility. To our knowledge, this is the first study of changes in acetabular version after PSO.

Arthroscopic resection of benign tumors of the knee posterior compartment: a report of 15 cases.

INTRODUCTION: The management of tumors located in the posterior compartment of the knee, whatever the nature of the tumor, remains surgical excision and can be done by open surgery or under arthroscopic control. The objective of this study was to evaluate the arthroscopic management of intra-articular tumors of the posterior compartment of the knee. The hypothesis is that tumors or tumor-like lesions confined to the posterior compartment are accessible by arthroscopy with low iatrogenic risk. MATERIALS AND METHODS: All patients with an intra-articular tumor of the posterior compartment of the knee were enrolled between 2009 and 2013. The surgical management consisted of arthroscopic resection. Patients underwent postoperative MRI, repeated at last follow-up. The outcomes were the occurrence of complications, functional evaluation using the Lysholm Knee Scoring Scale, and the recurrence rate. RESULTS: Fifteen patients were included. All patients had a complete resection. One case of delayed healing of the arthroscopic entry point was observed. At a mean 22months, the mean Lysholm Knee Score increased from 74 (±8.5) preoperatively to 92 (±7.7) postoperatively, a significant increase of 18 points (P=0.001). One patient had a recurrence of osteochondromatosis, requiring removal of a foreign body. DISCUSSION: Resection of posterior intra-articular tumors of the knee using arthroscopy is possible, subject to a learning curve.