Tibiofemoral lift-off and resulting laxity following total knee arthroplasty: Frequency in a series of 906 continuous cases and functional consequences at 4 years' follow-up in a case-control study.

BACKGROUND: Tibiofemoral instability is one reason for early revision of total knee arthroplasty. It can be the consequence of tibiofemoral laxity, especially in the coronal plane with tibiofemoral lift-off. But does femoral condyle lift-off on conventional postoperative radiographs suggest the presence of laxity or potential instability? To our knowledge, this question has not yet been answered. This led us to conduct a retrospective study to evaluate (1) the frequency of lift-off on postoperative radiographs, (2) the relationship between lift-off and laxity in the short term and (3) the functional consequences of lift-off. HYPOTHESIS: Postoperative lift-off is a rare event that is predictive of laxity. METHODS: We carried out a single-center retrospective study using postoperative radiographs from patients who underwent primary total knee arthroplasty between 2014 and 2016. The sample consisted of 906 patients. Lift-off was defined as a tibiofemoral angle of 3° or more on immediate postoperative radiographs (day 0) that were non-weightbearing and had no stress applied. The functional outcomes were determined in the 17 patients identified as having lift-off who had been operated in the first year (2014) to ensure the follow-up was long enough. These patients were compared to 34 matched control patients who were operated the same year and chosen randomly among patients not having lift-off. The matching ratio was 2 controls to 1 case. Preoperative and surgical data were compiled from each patient's electronic medical record. Patients were evaluated at 4 years postoperatively using the subjective Oxford-48, objective HSS score, IKS score, overall patient satisfaction and stress radiographs of the knee. The cases of lift-off observed in 2014 (n=17) were paired with a control group of patients selected randomly during 2014. RESULTS: The frequency of the lift-off event was 63/906 or 7%. The frequency was consistent over the three years studied: 7.1% in 2014 (19/269), 6.2% in 2015 (22/354) and 7.8% in 2016 (22/283). There was no significant difference between the two groups (17 with lift-off and 34 without) in the sex, age, body mass index and coronal plane deformity (preoperative HKA angle). At a mean follow-up of 4 years (range 12-49 months), the knees with postoperative lift-off had more laxity (p=0.002), particularly laxity when varus stress was applied (p=0.009). There were no other significant differences in the outcomes. DISCUSSION: Immediate postoperative lift-off after total knee arthroplasty is not a rare event, with a 7% frequency in our study. While it reveals that laxity is present in the particular compartment, there is no evidence of functional consequences at 4 years' follow-up; however, a long-term assessment is required to verify this finding. LEVEL OF EVIDENCE: III - case-control study.

Arthroscopic treatment of type I and II greater trochanteric pain syndrome.

The goal of this study was to describe and evaluate endoscopic bursectomy combined with fascia lata lengthening in the treatment of type I and II greater trochanteric pain syndrome recalcitrant to conservative management. This was a retrospective study of 20 patients (7 type I, 13 type II) reviewed with a minimum follow-up of 2 years. The mean follow-up was 44±11 [26-65] months. While significant improvements in pain, mHHS and NAHS were found, 80% of patients still had hip pain graded at≥3 on VAS. The satisfaction rate was 7/10±2 [3-10]. Snapping in the hip had been eliminated in 100% of cases. No complications were observed. This is a minimally invasive surgery that is feasible in patients who have failed an optimal course of conservative treatment. But patients must be informed that pain might not be completely eliminated by this procedure. LEVEL OF EVIDENCE: IV; retrospective, case series.

Does the alpha-defensin lateral flow test conserve its diagnostic properties in a larger population of chronic complex periprosthetic infections? Enlargement to 112 tests, from 42 tests in a preliminary study, in a reference center.

BACKGROUND: Diagnosis of periprosthetic infection (PPI) is crucial for management of bone and joint infection. The preoperative gold-standard is joint aspiration, providing results after 2-14 days' culture, with non-negligible false negative rates due to the fragility of certain micro-organisms and/or prior antibiotic treatment. The Synovasure™ alpha-defensin lateral flow test (Zimmer, Warsaw, IN, USA) contributes within minutes to joint fluid diagnosis of almost all infectious agents, including in case of concomitant antibiotic therapy. Validity remains controversial, notably in complex microbiological situations: multi-operated patients, diagnostic doubt despite iterative sterile culture, long-course antibiotic therapy. We extended a prospective study reported in 2018, to determine whether the test maintained diagnostic value in a larger population, assessing 1) negative (NPV) and positive (PPV) predictive value, and 2) sensitivity and specificity. HYPOTHESIS: Synovasure™ maintains NPV above 95% in a broader population of microbiologically complex suspected PPI. MATERIAL AND METHODS: Synovasure™'s performance was assessed between October 2015 and October 2019 in 106 patients (112 tests) in complex diagnostic situations: 37 discordant cultures (discordant findings between 2 samples), 65 cases with clinically or biologically suspected infection but iterative sterile culture, 10 emergencies (requiring surgery, precluding antibiotic window, or mechanical failure in suspected infection), including 5 with ongoing antibiotic therapy for infection in another organ. Six tests were repeated in the same patient and same joint at >6 months' interval for strong clinical suspicion of infection. The main endpoint was the MSIS score (MusculoSkeletal Infection Society, 2018). RESULTS: NPV was 98.8%, PPV 72.4%, sensitivity 95.5% and specificity 91%. Prevalence of infection was 19.6%. Only 1 of the 22 infected patients had negative Synovasure™ tests, compared to 81 of the 84 non-infected patients. CONCLUSION: Synovasure™ is a reliable novel diagnostic test, contributing mainly to ruling out infection thanks to its strong NPV. The cost imposes sparing use, but medico-economic assessment would be worthwhile. LEVEL OF EVIDENCE: III; prospective of diagnostic performance.

A Comparison of Outcomes After Endoscopic Repair of Partial- Versus Full-Thickness Tears of the Gluteus Medius Tendon.

PURPOSE: The purpose of this study was to evaluate and compare the functional outcomes after endoscopic repair of partial or full-thickness gluteus medius tears at a minimum 2 years' follow-up. METHODS: Patients with isolated tears of the gluteus medius tendon repaired endoscopically between 2012 and 2017 were evaluated at a minimum 2 years of follow-up. Patients with large, retracted and/or irreducible tears, advanced atrophy, or fatty degeneration or with concomitant other hip pathology were excluded. Functional outcomes were assessed using the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), and visual analog scale (VAS) for pain preoperatively and at the last follow-up RESULTS: Forty-six patients, 3 men and 43 women with a mean (SD) age of 63 (9; range, 43-82) years, were included. Thirty-three patients (72%) had partial-thickness tears and 13 (28%) had full-thickness tears. Pain was reduced significantly from a median of 8 (IQR: 6-8) at the preoperative visit to a median of 2 (IQR: 15) at the most recent follow-up (P < .0001). The mHHS and NAHS improved significantly from a median of 44 (IQR: 35-52) to 80 (IQR: 64-87) (P < .0001) and 52 (IQR: 43-56) to 75 (IQR: 66-94) (P < .0001), respectively. These improvements were clinically relevant and surpass the reported minimal clinically important difference. Patients with partial tears had significant functional gains in the mHHS in comparison with patients with full-thickness tears (P = .02). No other statistically significant difference between groups of tear grade was observed. CONCLUSIONS: Endoscopic repair of gluteus medius tendon tears yields excellent functional outcomes at a minimum follow-up of 2 years. A lower functional improvement for full-thickness tears was observed; this difference was statistically significant for 1 of the 2 scores evaluated. LEVEL OF EVIDENCE: Level III, retrospective comparative cohort.

A profile on the Synovasure alpha defensin test for the detection of periprosthetic infections.

INTRODUCTION: Clinicians have waited a long time for a 'universal' marker that may help them distinguish infected from non-infected total joint arthroplasties when doubts persist after using classical clinical and biological signs of infection. In recent years, synovial fluid biomarkers including leukocyte esterase, alpha-defensins, and CRP have shown promising results for the diagnosis of periprosthetic joint infections (PJIs). AREAS COVERED: This review provides an overview of the rational and the use of the Synovasure® alpha-defensin tests in patients with a suspicion of PJI. Using a systematic investigation by keywords, we looked for all citations (and the citations to these citations) of the selected papers. EXPERT OPINION: The Synovasure® alpha-defensin tests demonstrate high potential for the diagnosis of PJIs. However, the data currently available also show that the universal marker of infection in the settings of PJIs is still to be discovered.

Spinopelvic parameters in greater trochanteric pain syndrome: a retrospective case-control study.

PURPOSE: Greater trochanteric pain syndrome (GTPS) is a condition resulting in lateral hip pain, most commonly caused by tendinosis or tear of the gluteus medius and minimus tendons, and greater trochanteric bursitis. Our aim was to assess pelvic parameters and proximal femoral anatomy in patients suffering from surgical-stage GTPS compared with a control group. METHODS: This retrospective, case-control study assessed 43 patients suffering from GTPS, matched according to age, gender, body mass index and level of sport and physical activity to 43 control patients, between 2013 and 2018. Pelvic parameters, including pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS), and proximal femoral anatomy, including femoral offset (FO) and neck-shaft angle (NSA), were measured using the EOS Imaging™ system. RESULTS: GTPS patients had a significantly lower mean (± SD) SS than control patients (33.1 ± 10.4 vs. 39.6 ± 9.7°, respectively; p < 0.05). There was no significant difference in PT (21.3 ± 7.1 vs. 19.0 ± 7.2°), PI (53.5 ± 11.6 vs. 57.7 ± 10.5°), FO (40.4 ± 8 vs. 42.2 ± 6.8°) or NSA (125.1 ± 5.8 vs. 124.4 ± 4.7°). There was no difference in lower back pain symptoms in a subgroup analysis of GTPS patients. CONCLUSIONS: Sacral slope was lower in patients with surgical-stage GTPS than in asymptomatic hip patients, using the EOS Imaging™ system.