Unicompartmental knee arthroplasty: Modes of failure and conversion to total knee arthroplasty

Despite the excellent success rates of the modern unicompartmental knee arthroplasty (UKA), results of knee replacement registries still shows a relatively high revision and failure rate for UKA, especially when compared with traditional total knee arthroplasty (TKA). Bearing dislocation continues to be advocated as the predominant mechanism of failure inmobile UKA, whereas polyethylene wear and aseptic loosening remains the main cause of failure of fixed UKA. Degeneration of the unreplaced compartments has been reported in both mobile and fixed designs. When the revision is required, most of failed UKAs are converted to TKAs. Surgical challenges of the UKA revision, and outcomes of UKA converted to TKA are still debated in literature.Despite the excellent success rates of the modern unicompartmental knee arthroplasty (UKA), results of knee replacement registries still shows a relatively high revision and failure rate for UKA, especially when compared with traditional total knee arthroplasty (TKA). Bearing dislocation continues to be advocated as the predominant mechanism of failure inmobile UKA, whereas polyethylene wear and aseptic loosening remains the main cause of failure of fixed UKA. Degeneration of the unreplaced compartments has been reported in both mobile and fixed designs. When the revision is required, most of failed UKAs are converted to TKAs. Surgical challenges of the UKA revision, and outcomes of UKA converted to TKA are still debated in literature

Articulated spacer provides long-term knee improvement after two-stage reimplantation

Purpose: The purpose of this study was to determine the long-term outcome in patients who underwent two-stage reimplantation with an articulated spacer following a chronic periprosthetic knee infection. The hypothesis was that the use of an articulated spacer provides significant improvement of clinical results and knee functionality through a long follow-up period, and therefore a durable revision TKA. Methods: Forty-six consecutive patients (46 knees) who underwent two-stage reimplantation with an articulated spacer for a chronic periprosthetic knee infection were retrospectively analysed. An articulated cement spacer, moulded in surgery room, was implanted in all cases. Patients were followed for a median period of 12 (range 6–16) years, and no patients were lost to follow-up. Patients were assessed preoperatively and postoperatively through the IKS knee and function scores and ROM. Results: Two-stage reimplantation was successful in controlling the infection in 91.3 % of patients. In the 42 patients with a successful two-stage revision, the median IKS knee and function scores were 36 (range 16–56) points and 25 (range 15–35) points, respectively, before the operation, and 76 (range 52–94) points and 70 (range 55–90) points (p < 0.001) at the last follow-up. The median ROM increased from 80 (range 60–110) degrees preoperatively to 115 (range 100–128) degrees (p < 0.01) at the last follow-up. Conclusions: Two-stage septic revision with an articulated cement spacer provided a significant long-term improvement of preoperative clinical and functional knee scores and therefore a durable revision TKA. Level of evidence: Retrospective case series, Level IV.Purpose: The purpose of this study was to determine the long-term outcome in patients who underwent two-stage reimplantation with an articulated spacer following a chronic periprosthetic knee infection. The hypothesis was that the use of an articulated spacer provides significant improvement of clinical results and knee functionality through a long follow-up period, and therefore a durable revision TKA. Methods: Forty-six consecutive patients (46 knees) who underwent two-stage reimplantation with an articulated spacer for a chronic periprosthetic knee infection were retrospectively analysed. An articulated cement spacer, moulded in surgery room, was implanted in all cases. Patients were followed for a median period of 12 (range 6–16) years, and no patients were lost to follow-up. Patients were assessed preoperatively and postoperatively through the IKS knee and function scores and ROM. Results: Two-stage reimplantation was successful in controlling the infection in 91.3 % of patients. In the 42 patients with a successful two-stage revision, the median IKS knee and function scores were 36 (range 16–56) points and 25 (range 15–35) points, respectively, before the operation, and 76 (range 52–94) points and 70 (range 55–90) points (p < 0.001) at the last follow-up. The median ROM increased from 80 (range 60–110) degrees preoperatively to 115 (range 100–128) degrees (p < 0.01) at the last follow-up. Conclusions: Two-stage septic revision with an articulated cement spacer provided a significant long-term improvement of preoperative clinical and functional knee scores and therefore a durable revision TKA. Level of evidence: Retrospective case series, Level IV

Good clinical results with autologous matrix-induced chondrogenesis (Amic) technique in large knee chondral defects

Purpose: Autologous matrix-induced chondrogenesis (AMIC) is a treatment for focal full-thickness cartilage defects combining microfracturing with an exogenous I/III collagen matrix (Chondro-Gide). The aim of the present study was to determine the 7 years outcomes of patients treated with the AMIC technique for knee chondral defects larger than 2 cm2. The hypothesis was that the positive short-term outcomes achieved in the previous series would not deteriorate at a 7-year follow-up. Methods: Twenty-one patients treated with the AMIC technique were retrospectively analysed. Patients were assessed through the IKDC subjective knee evaluation questionnaire and the Lysholm scoring system. All patients underwent a complete imaging study including radiographs and magnetic resonance. The median defect size was found to be 4.3 (range 2.9–8) cm2. Results: At a median follow-up of 7 (±1.4) years, the mean IKDC score improved from 31.7 (±8.9) points preoperatively, to 80.6 (±5.3) at the latest follow-up (p < 0.05). The mean Lysholm score improved from 38.8 (±12.4) points preoperatively to 72.6 (±19.5) points at the last follow-up (p < 0.05). At the last follow-up, 76.2% of patients were satisfied or extremely satisfied with their outcomes, while 66.6% of patients showed good quality repair tissue on magnetic resonance imaging. Conclusion: AMIC was found to be an effective method to treat full-thickness knee chondral defects larger than 2 cm2, with significant clinical and functional improvement maintained over a 7-year follow-up. Level of evidence: IV.Purpose: Autologous matrix-induced chondrogenesis (AMIC) is a treatment for focal full-thickness cartilage defects combining microfracturing with an exogenous I/III collagen matrix (Chondro-Gide). The aim of the present study was to determine the 7 years outcomes of patients treated with the AMIC technique for knee chondral defects larger than 2 cm2. The hypothesis was that the positive short-term outcomes achieved in the previous series would not deteriorate at a 7-year follow-up. Methods: Twenty-one patients treated with the AMIC technique were retrospectively analysed. Patients were assessed through the IKDC subjective knee evaluation questionnaire and the Lysholm scoring system. All patients underwent a complete imaging study including radiographs and magnetic resonance. The median defect size was found to be 4.3 (range 2.9â\u80\u938) cm2. Results: At a median follow-up of 7 (±1.4) years, the mean IKDC score improved from 31.7 (±8.9) points preoperatively, to 80.6 (±5.3) at the latest follow-up (p < 0.05). The mean Lysholm score improved from 38.8 (±12.4) points preoperatively to 72.6 (±19.5) points at the last follow-up (p < 0.05). At the last follow-up, 76.2% of patients were satisfied or extremely satisfied with their outcomes, while 66.6% of patients showed good quality repair tissue on magnetic resonance imaging. Conclusion: AMIC was found to be an effective method to treat full-thickness knee chondral defects larger than 2 cm2, with significant clinical and functional improvement maintained over a 7-year follow-up. Level of evidence: IV

Long-Term Clinical and Radiographic Outcomes of Porous Tantalum Monoblock Acetabular Component in Primary Hip Arthroplasty: A Minimum of 15-Year Follow-Up

Background The porous tantalum monoblock cup has demonstrated excellent short-term and midterm clinical and radiographic outcomes in primary THA, but longer follow-up is necessary to confirm the durability of these results into the second decade. The purpose of this study is to report the clinical and radiographic outcomes for this monoblock cup with a minimum 15-year follow-up. Methods From June 1998 to December 1999, 61 consecutive patients (63 hips) underwent primary THA with a tantalum monoblock acetabular component. All patients were followed clinically and radiographically for a minimum of 15 years. At a mean of 15.6 years (range, 15-16 years) of follow-up, 5 patients had died, and 4 had been lost to follow-up, leaving 52 patients (54 hips) for analysis. The underlying diagnosis that led to the primary THA was primary osteoarthritis in 43 hips, avascular necrosis in 4, developmental hip dysplasia in 3, rheumatoid arthritis in 3 and post-traumatic osteoarthritis in 1. Results One cup was revised for deep infection; at surgery, the cup showed osseointegration. At a mean follow-up of 15.6 years (range, 15-16 years), the survivorship with cup revision for aseptic loosening as end point was 100%. There was no radiographic evidence of loosening, migration, or gross polyethylene wear at last follow-up. The mean Harris Hip Scores improved from 47 points preoperatively to 94 points. Conclusion The porous tantalum monoblock cup in primary THA demonstrated excellent clinical and radiographic outcomes with no failures because of osteolysis or loosening at a minimum follow-up of 15 years

Tantalum Cones Provide Durable Mid-term Fixation in Revision TKA

Background: Multiple studies have reported favorable short-term outcomes using tantalum cones to reconstruct massive bone defects during revision TKA. However, longer-term followup is needed to determine the durability of these reconstructions. Questions/purposes: We wished to determine the mid-term (1) reoperation rates for septic and aseptic causes, (2) radiologic findings of osseointegration, and (3) clinical outcomes based on the Knee Society score in patients who underwent revision knee arthroplasty with tantalum cones for severe bone loss. Methods: We retrospectively evaluated records of 18 patients (18 knees) who underwent revision knee arthroplasty with use of tantalum cones between 2005 and 2008; the primary indications for use of this approach were to reconstruct massive bone defects classified as Anderson Orthopaedic Research Institute Types 2B and 3. During this period, all defects of this type were treated with this approach and no cones were used for more-minor defects. A total of 26 cones (13 tibial and 13 femoral) were implanted. There were 12 female and six male patients with a mean age of 73 years (range, 55\u201384 years) at the time of revision. The indication for the revision included aseptic loosening (five patients) and second-stage reimplantation for deep infection (13 patients). Patients were followed for a mean of 6 years (range, 5\u20138 years). No patient was lost to followup. Clinical and radiographic outcomes were assessed with the Knee Society clinical rating system and radiographic evaluation system. Results: There have been two reoperations for recurrent infection; at surgery, the two cones showed osseointegration. No evidence of loosening or migration of any implant was noted on the most recent radiographs. Knee Society knee scores improved from a mean of 31 points before surgery to 77 points at latest followup (p&nbsp;&lt;&nbsp;0.001), and function scores improved from a mean of 22 points to 65 points (p&nbsp;&lt;&nbsp;0.001). Conclusions: Tantalum cones for reconstruction of massive bone defects in revision knee arthroplasty provided secure fixation with excellent results at average followup of 6 years, although this series included relatively few patients. These devices are a viable option for surgeons to use in situations with severe bone loss. Further studies with longer followups are needed to confirm the durability of these reconstructions. Level of Evidence: Level IV, therapeutic study

Early intraprosthetic dislocation in dual-mobility implants: a systematic review

Background: Dual mobility implants are subject to a specific implant-related complication, intraprosthetic dislocation (IPD), in which the polyethylene liner dissociates from the femoral head. For older generation designs, IPD was attributable to late polyethylene wear and subsequent failure of the head capture mechanism. However, early IPDs have been reportedly affecting contemporary designs. Methods: A systematic review of the literature according to the preferred reporting items for systematic reviews and meta-analyses guidelines was performed. A comprehensive search of PubMed, MEDLINE, Embase, and Google Scholar was conducted for English articles between January 1974 and August 2016 using various combinations of the keywords “intraprosthetic dislocation,” “dual mobility,” “dual-mobility,” “tripolar,” “double mobility,” “double-mobility,” “hip,” “cup,” “socket,” and “dislocation.” Results: In all, 16 articles met our inclusion criteria. Fourteen were case reports and 2 were retrospective case series. These included a total of 19 total hip arthroplasties, which were divided into 2 groups: studies dealing with early IPD after attempted closed reduction and those dealing with early IPD with no history of previous attempted closed reduction. Early IPD was reported in 15 patients after a mean follow-up of 3.2 months (2.9 SD) in the first group and in 4 patients after a mean follow-up of 15.1 months (9.9 SD) in the second group. Conclusions: Based on the current data, most cases have been preceded by an attempted closed reduction in the setting of outer, large articulation dislocation, perhaps indicating an iatrogenic etiology for early IPD. Recognition of this possible failure mode is essential to its prevention and treatment