Jérôme Delambre

Ceramic-on-ceramic THA Implants in Patients Younger Than 20 Years

BackgroundPoor survival of THA implants in very young patients has been attributed to use of cemented implants, wear of conventional polyethylene, and the presence of morphologic deformities in the proximal femur or in the acetabulum. Few studies have reported the long-term results of ceramic-on-ceramic implants in THAs in patients younger than 20 years.Question/purposesWe determined: (1) the proportion of patients who experienced complications related to the ceramic bearing (squeaking, fracture); (2) the survivorship free from loosening and free from revision for any reason; (3) whether patients with osteonecrosis had inferior survivorship compared with patients whose surgical indication was all other diagnoses including sequelae of pediatric hip disorders (developmental dysplasia of the hip, Legg-Calvé-Perthes disease, slipped capital femoral epiphysis); and (4) clinical function.MethodsBetween 1979 and 2013, we performed 113 primary THAs in 91 patients younger than 20 years at the time of surgery. Of those, 105 THAs (83 patients) were done with ceramic-on-ceramic bearings (91% of the 91 patients); during that period, a ceramic-on-ceramic bearing couple was indicated in all patients younger than 20 years. In eight patients (eight hips), a cemented polyethylene cup was implanted because the diameter of the acetabulum was smaller than the smallest available ceramic cup (46 mm), or because adequate fixation of a ceramic press-fit cup could not be achieved despite careful reaming of the acetabulum. The most common diagnosis indicating THA was avascular necrosis of the femoral head (56.2%; 59 hips). Thirty-five patients (40 hips) had undergone previous operations before the replacement. Three patients (4%; four hips) died from unrelated causes, nine patients (11%; 13 hips) were lost to followup, and four patients (five hips) had a followup greater than 8.5 years but have not been seen in the last 5 years. Patients were assessed clinically (using the Merle d’Aubigne-Postel score, Hip disability and Osteoarthritis Outcome score (HOOS), and the SF-12® Health Survey, and radiographically for signs of radiolucencies, subsidence, or osteolysis on plain films. The mean followup was 8.8 ± 6.1 years (range, 2–34.4 years).ResultsFive patients experienced transient noise generation, defined as a snap in four patients and squeaking in one. Seventeen hips underwent revision surgery—16 for aseptic loosening and one for septic loosening. The implant survival rate at 10 years with aseptic loosening as the endpoint was 90.3% (95% CI, 82.4%–98.9%). No hip had acetabular or femoral osteolysis. Survivorship in patients with osteonecrosis did not differ from survivorship in patients with other diagnoses. The Merle d’Aubigne-Postel score increased from 10.1 ± 4.0 to 17.6 ± 1.1 (p < 0.01); the mean HOOS score was 79.3 ± 13.8 (range, 50.6–100); the mean SF-12® physical and mental component scores were 48.1 ± 7.9 (range, 21.4–57.6), and 47.4 ± 12.2 (range, 24.5–99.4), respectively.ConclusionsWe found that patient-reported outcomes scores improved in most patients undergoing THA in this very young study group. Underlying diagnosis did not affect long-term survivorship. However, the revision-free survival rate at 10 years is lower than published estimates in older patients, and with 11% of patients lost to followup, our estimates may represent a best-case scenario. Therefore, we believe THA should be performed as a last resort in this population.Level of EvidenceLevel IV, therapeutic study.

Ceramic-on-ceramic THA associated with fewer dislocations and less muscle degeneration by preserving muscle progenitors.

BackgroundDislocation is a common complication after total hip arthroplasty (THA). Although the etiology of dislocation is multifactorial, longer-term changes in muscle such as atrophy may influence the risk of prosthetic dislocation. Biological differences in wear products generated by different bearing surfaces may influence differences in the appearance of periarticular muscle after THA; however, such bearing-associated differences to our knowledge have not been studied in vivo, and few studies have evaluated bearing-associated differences in dislocation risk.Questions/purposes(1) Is there a correlation between the postoperative risk of dislocation at revision and the bearing surfaces of the primary arthroplasty? (2) Is there a higher extent of fatty muscle atrophy on CT scan in hips with osteolysis (polyethylene hips) as compared with hips without osteolysis (ceramic-on-ceramic hips)? (3) Are these two abnormalities (bone osteolysis and fatty atrophy) associated with a decrease of mesenchymal stem cells (MSCs) in bone and in muscle?MethodsWe retrospectively evaluated 240 patients (240 hips) who had a THA revision (98% of which, 235 of the 240, were isolated acetabular revisions) and a normal contralateral hip. All patients had received the same implants for the primary arthroplasty (32-mm head) except for bearing surfaces (80 hips with ceramic-on-ceramic, 160 with polyethylene). No differences were noted between the groups in terms of age, sex, body mass index, proportion of patients who had a dislocation after the index arthroplasty but before the revision, and proportion of the patients with stem loosening in addition to acetabular loosening. Indications for revision generally were cup loosening. The revisions in the hips with polyethylene bearings generally had more acetabular bone loss, but the position of the center of the cup and the orientation of the cup were similar after reconstruction in the two groups. Before revision, osteolysis, muscle atrophy, and fatty degeneration were evaluated on CT scan and compared with the contralateral side. Bone muscle progenitors were evaluated by bone marrow MSCs and satellite cells for muscle. At revision, all the hips received the same implants with the same head diameter (32 mm) and a standard liner. Revisions were performed between 1995 and 2005. The followup after revision was at a mean of 14 years (range, 10–20 years) for ceramic revision and 12 years (range, 10–20 years) for polyethylene hips, and there was no differential loss to followup between the groups.ResultsMore hips with polyethylene liners at the time of index arthroplasty dislocated after revision than did hips with ceramic liners (18% [29 of 160] compared with 1% [one of 80]; odds ratio, 17.5; 95% confidence interval, 2.3363–130.9100; p = 0.005). For the 80 hips with ceramic-on-ceramic, no osteolysis was detected before revision; there was no muscle fatty degeneration of the gluteus muscles on CT scan or histology. For the 160 hips with polyethylene liners, osteolytic lesions on the acetabulum and femur were observed in 100% of the hips. The increased atrophy of the gluteus muscles observed on CT scan correlated with the increase of osteolysis (r = 0.62; p = 0.012). The surgical limbs in the patients with polyethylene hips as compared with ceramic-on-ceramic hips demonstrated a greater reduction in cross-sectional area (respectively, 11.6% compared with 3%; odds ratio, 3.82; p < 0.001) and radiological density (41% [14.1/34.1] compared with 9%; odds ratio, 6.8; p = 0.006) of gluteus muscles when compared with the contralateral normal side. (41% compared with 9%; odds ratio, 6.8; p = 0.006).ConclusionsCeramic bearing surfaces were associated with fewer dislocations after revision than polyethylene bearing surfaces. The reasons of the lower rate of dislocation with ceramic-on-ceramic bearings may be related to observed differences in the periarticular muscles (fat atrophy or not) with the two bearing surfaces.Level of EvidenceLevel III, therapeutic study.

Direct anterior Hueter approach is a safe and effective approach to perform a bipolar hemiarthroplasty for femoral neck fracture: Outcome in 82 patients

Background and purpose — The direct anterior (DA) approach in total hip arthroplasty has recently been associated with faster functional recovery than the posterolateral (PL) approach. We hypothesized that the same should hold for the DA approach in bipolar hemiarthroplasty for femoral neck fractures. Patients and methods — 82 patients with a displaced femoral neck fracture and candidates for bipolar hemiarthroplasty were enrolled after IRB approval in this prospective non-randomized comparative study (DA: n = 38; PL: n = 44). The postoperative protocols were similar in both groups. Evaluation included surgical complications, component placement, and early functional outcomes, assessed 6 weeks postoperatively using a timed up-and-go (TUG) test. The incidence of dislocation was assessed by telephone interview at least 1 year after the surgery. Results — The DA-group patients had better results in the TUG test than the PL-group patients 6 weeks after surgery: half were under 19 seconds as opposed to only one third for PL (p = 0.06). We did not record any intraoperative femoral fracture or any lateral femoral cutaneous neuropraxia in the DA group. We observed a significant difference (p = 0.04) in lateral offset between the PL group (4.2 (SD 6.4) mm) and the DA group (−1.6 (SD 8.5) mm). Stem alignment was similar between groups. The dislocation rate for DA patients was lower than for PL patients (1 of 38 cases vs. 9 of 44 cases; p = 0.02). Interpretation — Our findings indicate that relative to the posterolateral approach, the direct anterior approach for bipolar hemiarthroplasty may improve gait in the early postoperative period and decrease the dislocation rate.

Incidence and impact of implant subsidence after stand-alone lateral lumbar interbody fusion

BACKGROUND Few data are available on the occurrence after stand-alone lateral lumbar interbody fusion (LLIF) of implant subsidence, whose definition and incidence vary across studies. The primary objective of this work was to determine the incidence of subsidence 1 year postoperatively, using an original measurement method, whose validity was first assessed. The secondary objective was to assess the clinical impact of subsidence. HYPOTHESIS Implant subsidence after stand-alone LLIF is a common complication that can adversely affect clinical outcomes. MATERIAL AND METHODS Of 69 included patients who underwent stand-alone LLIF, 67 (97%) were re-evaluated at least 1 year later. Furthermore, 63 (91%) patients had two available computed tomography (CT) scans for assessing subsidence, one performed immediately after surgery and the other 1 year later. Reproducibility of the original measurement method was assessed in a preliminary study. Subsidence was defined as at least 4mm loss of fused space height. RESULTS The incidence of subsidence was 32% (20 patients). Subsidence was global in 7 (11%) patients and partial in 13 (21%) patients. Mean loss of height was 5.5±1.5mm. Subsidence predominated anteriorly in 50% of cases. The lordotic curvature of the fused segment was altered in 50% of patients, by a mean of 8°±3°. Fusion was achieved in 67/69 (97%) patients. The Oswestry score and visual analogue scale scores for low-back and nerve-root pain were significantly improved after 1 year in the overall population and in the groups with and without subsidence. DISCUSSION Reproducibility of our measurement method was found to be excellent. Subsidence was common but without significant clinical effects after 1 year. Nevertheless, subsidence can be associated with pain and can result in loss of lumbar lordosis, which is a potential risk factor for degenerative disease of the adjacent segments. A score for predicting the risk of subsidence will now be developed by our group as a tool for improving patient selection to stand-alone LLIF. LEVEL OF EVIDENCE IV, retrospective cohort study.