Adolph V. Lombardi

Why knee replacements fail in 2013

Previous studies of failure mechanisms leading to revision total knee replacement (TKR) performed between 1986 and 2000 determined that many failed early, with a disproportionate amount accounted for by infection and implant-associated factors including wear, loosening and instability. Since then, efforts have been made to improve implant performance and instruct surgeons in best practice. Recently our centre participated in a multi-centre evaluation of 844 revision TKRs from 2010 to 2011. The purpose was to report a detailed analysis of failure mechanisms over time and to see if failure modes have changed over the past 10 to 15 years. Aseptic loosening was the predominant mechanism of failure (31.2%), followed by instability (18.7%), infection (16.2%), polyethylene wear (10.0%), arthrofibrosis (6.9%) and malalignment (6.6%). The mean time to failure was 5.9 years (ten days to 31 years), 35.3% of all revisions occurred at less than two years, and 60.2% in the first five years. With improvements in implant and polyethylene manufacture, polyethylene wear is no longer a leading cause of failure. Early mechanisms of failure are primarily technical errors. In addition to improving implant longevity, industry and surgeons must work together to decrease these technical errors. All reports on failure of TKR contain patients with unexplained pain who not infrequently have unmet expectations. Surgeons must work to achieve realistic patient expectations pre-operatively, and therefore, improve patient satisfaction post-operatively.

Are Custom Triflange Acetabular Components Effective for Reconstruction of Catastrophic Bone Loss

BackgroundAlthough the introduction of ultraporous metals in the forms of acetabular components and augments has increased the orthopaedic surgeon’s ability to reconstruct severely compromised acetabuli, there remain some that cannot be managed readily using cups, augments, or cages. In such situations, allograft-prosthetic composites or custom acetabular components may be called for. However, few studies have reported on the results of these components.Questions/purposesThe purposes of this study were to determine the (1) frequency of repeat revision, (2) complications and radiographic findings, and (3) Harris hip scores in patients who underwent complex acetabular revision surgery with custom acetabular components.MethodsBetween August 2003 and February 2012, 26 patients (28 hips) have undergone acetabular reconstruction with custom triflange components. During this time, the general indications for using these implants included (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. This approach was used in a cohort of patients with Paprosky Type 3B acetabular defects, which represented 3% (30 of 955) of the acetabular revisions we performed during the study period. Minimum followup was 2xa0years (mean, 57xa0months; range, 28–108xa0months). Seven patients (eight hips) died during the study period, and three (11%) of these patients (four hips; 14%) were lost to followup before 2xa0years, leaving 23 patients (24 hips) with minimum 2-year followup. Sixteen patients were women. The mean age of the patients was 67xa0years (range, 47–85xa0years) and mean BMI was 28xa0kg/m2 (range, 23–39xa0kg/m2). Revisions and complications were identified by chart review; hip scores were registered in our institution’s longitudinal database. Pre- and postoperative radiographs were analyzed by the patient’s surgeon to determine whether migration, fracture of fixation screws, or continued bone loss had occurred.ResultsThere have been four subsequent surgical interventions: two failures secondary to sepsis, and one stem revision and one open reduction internal fixation for periprosthetic femoral fracture. There were two minor complications managed nonoperatively, but all of the components were noted to be well-fixed with no obvious migration or loosening observed on the most recent radiographs. Harris hip scores improved from a mean of 42 (SD,xa0±xa016) before surgery to 65 (SD,xa0±xa018) at latest followup (pxa0<xa00.001).ConclusionsCustom acetabular triflange components represent yet another tool in the reconstructive surgeon’s armamentarium. These devices can be helpful in situations of catastrophic bone loss.Level of EvidenceLevel IV, therapeutic study.

A mini-anterior approach to the hip for total joint replacement: optimising results: improving hip joint replacement outcomes

Direct anterior approaches to the hip have gained popularity as a minimally invasive method when performing primary total hip replacement (THR). A retrospective review of a single institution joint registry was performed in order to compare patient outcomes after THR using the Anterior Supine Intermuscular (ASI) approach versus a more conventional direct lateral approach. An electronic database identified 1511 patients treated with 1690 primary THRs between January 2006 and December 2010. Our results represent a summary of findings from our previously published work. We found that patients that underwent an ASI approach had faster functional recovery and higher Harris hip scores in the early post-operative period when compared with patients who had a direct lateral approach The overall complication rate in our ASI group was relatively low (1.7%) compared with other series using the same approach. The most frequent complication was early periprosthetic femoral fractures (0.9%). The dislocation rate in our series was 0.4% and the prosthetic joint infection rate was 0.1%. We suggest that the ASI approach is acceptable and safe when performing THR and encourages early functional recovery of our patients.

Large-diameter metal-on-metal total hip arthroplasty: dislocation infrequent but survivorship poor.

BackgroundUse of large-diameter metal-on-metal (MoM) articulations in THA increased, at least in part, because of the possibility of achieving improved joint stability and excellent wear characteristics in vitro. However, there have been subsequent concerning reports with adverse reactions to metal debris (ARMD), pseudotumors, and systemic complications related to metal ions.Questions/purposesThe purpose of this study was to determine at a minimum of 2xa0years’ followup (1) the proportion of patients who experienced a dislocation; (2) the short-term survivorship obtained with these implants; (3) the causes of failure and the proportion of patients who developed ARMD; and (4) whether there were any identifiable risk factors for revision.MethodsWe reviewed the results of 1235 patients who underwent 1440 large-diameter MoM primary THAs at our institution using two acetabular devices from a single manufacturer with minimum 2-year followup. Large-diameter MoM devices were used in 48% (1695 of 3567) of primary THAs during the study period. We generally used these implants in younger, more active, higher-demand patients, in patients considered at higher risk of instability, and in patients with adequate bone stock to achieve stable fixation without use of screws. Clinical records and radiographs were reviewed to determine the incidence and etiology of revision. Patients whose hips were revised were compared with those not revised to identify risk factors; Kaplan-Meier survivorship analysis was performed as was multivariate analysis to account for potential confounding variables when evaluating risk factors. Minimum followup was 2xa0years (average, 7xa0years; range, 2–12xa0years); complete followup was available in 85% of hips (1440 of 1695).ResultsDislocation occurred in one hip overall (< 1%; one of 1440). Kaplan-Meier analysis revealed survival free of component revision was 87% at 12xa0years (95% confidence interval, 84%–90%). The two most common indications for revision were ARMD (48%; 47 of 108 hips revised) and loosening or failure of ingrowth (31%; 34 of 108). Risk factors for component revision were younger age at surgery (relative risk [RR] 0.98 per each increased year; p = 0.02), higher cup angle of inclination (RR 1.03 per each increased degree; p = 0.04), and female sex (RR 1.67; p = 0.03).ConclusionsLarge-diameter MoM THAs are associated with a very low dislocation rate, but failure secondary to ARMD and loosening or lack of ingrowth occur frequently. Patients with MoM THA should be encouraged to return for clinical and radiographic followup, and clinicians should maintain a low threshold to perform a systematic evaluation. Early diagnosis and appropriate treatment are recommended to prevent the damaging effects of advanced ARMD.Level of Evidence Level IV, Therapeutic study.

Radiographic Comparison of Mobile-Bearing Partial Knee Single-Peg Versus Twin-Peg Design

The femoral component and proprietary instrumentation of a mobile-bearing unicompartmental knee arthroplasty (UKA) was redesigned with an additional peg for enhanced fixation, 15° of extra femoral surface for contact in deep flexion, more rounded profile, better fit into the milled surface, and redesigned intramedullary based instrumentation. To assess the benefit of these changes, we compared postoperative radiographs of 219 single-peg and 186 twin-peg UKAs done in 2008-2011. All surviving knees demonstrated satisfactory position and alignment with no radiolucencies observed. Radiographic analysis showed improved and consistent component positioning with the twin-peg design implanted with updated instrumentation compared with the single-peg. The radiographic benefits of improved implant positioning using the twin-peg component and updated instrumentation are clear and carry tremendous potential. More robust follow-up is imperative.

Risk of Periprosthetic Fractures With Direct Anterior Primary Total Hip Arthroplasty

BACKGROUNDnDespite increasing interest in the anterior approach for cementless, primary total hip arthroplasty (THA), studies examining the incidence of periprosthetic fractures with this approach are lacking. The purpose of this study was to (1) investigate the incidence of early periprosthetic fractures associated with primary THA performed through an anterior supine intermuscular (ASI) approach without the use of a specialized table and (2) identify potential risk factors for these fractures.nnnMETHODSnWe identified 2869 primary THAs performed via the ASI approach using a single cementless, tapered titanium femoral component with short and standard length options between February 2007 and April 2014. Fifty-two percent of THAs were in female patients, whereas 48% were in males. Short stems were used in 59% vs standard length in 41%.nnnRESULTSnThere were 26 (0.9%) early periprosthetic femoral fractures, with 23 requiring revision. When looking at the potential risk factors of age, gender, body mass index, and stem length, the only significant finding was that increased age was associated with increased risk of femoral fracture. Logistic regression analysis revealed a significant age-fracture association for female gender only, which remained when controlled for body mass index, stem length, or both.nnnCONCLUSIONnThe muscle-sparing ASI approach appears to be a safe technique for performing primary THA when used in a suitable patient population. The early periprosthetic femoral fracture rate in our series may warrant consideration of using a different design or different approach in elderly female patients.

Which total knee replacement implant should I pick?: correcting the pathology: the role of knee bearing designs

Debate has raged over whether a cruciate retaining (CR) or a posterior stabilised (PS) total knee replacement (TKR) provides a better range of movement (ROM) for patients. Various sub-sets of CR design are frequently lumped together when comparing outcomes. Additionally, multiple factors have been proven to influence the rate of manipulation under anaesthetic (MUA) following TKR. The purpose of this study was to determine whether different CR bearing insert designs provide better ROM or different MUA rates. All primary TKRs performed by two surgeons between March 2006 and March 2009 were reviewed and 2449 CR-TKRs were identified. The same CR femoral component, instrumentation, and tibial base plate were consistently used. In 1334 TKRs a CR tibial insert with 3° posterior slope and no posterior lip was used (CR-S). In 803 there was an insert with no slope and a small posterior lip (CR-L) and in 312 knees the posterior cruciate ligament (PCL) was either resected or lax and a deep-dish, anterior stabilised insert was used (CR-AS). More CR-AS inserts were used in patients with less pre-operative ROM and greater pre-operative tibiofemoral deformity and flexion contracture (p < 0.05). The mean improvement in ROM was highest for the CR-AS inserts (5.9° (-40° to 55°) vs CR-S 3.1° (-45° to 70°) vs CR-L 3.0° (-45° to 65°); p = 0.004). There was a significantly higher MUA rate with the CR-S and CR-L inserts than CR-AS (Pearson rank 6.51; p = 0.04). Despite sacrificing or not substituting for the PCL, ROM improvement was highest, and the MUA rate was lowest in TKRs with a deep-dish, anterior-stabilised insert. Substitution for the posterior cruciate ligament (PCL) in the form of a PS design may not be necessary even when the PCL is deficient.

Do Sex and BMI Predict or Does Stem Design Prevent Muscle Damage in Anterior Supine Minimally Invasive THA

BackgroundCadaveric and clinical studies have suggested that, despite being touted as muscle-sparing, the direct anterior approach is still associated with muscle damage, particularly to the tensor fascia lata (TFL). Patient body mass index (BMI) and/or sex may also influence this parameter.Questions/purposesThe purposes of the study were to determine if using a shorter femoral component reduces TFL damage or if patient sex or increasing BMI increases intraoperative TFL damage in direct anterior THA.MethodsOver a 1-year period, 599 direct anterior THAs were performed by three experienced anterior hip surgeons; of those, 421 direct anterior hips had complete data (70%) and were included in the study. The amount of visible damage to the TFL was recorded before closure. Two stem types were used, a standard-length flat-wedge taper (standard) or a 3-cm shortened version of the same stem (short). Stem selection was based on timeframe of the surgery, surgeon preference, or matching a previous implant type. During the study period, the three surgeons performed an additional 225 primary THAs with other approaches such that the direct anterior approach represented 73% of the THAs performed. A member of the operating team, either a fellow or physician assistant, graded the extent of damage based on a 0 to 3 scale. On this scale, 0 represented no muscle fiber damage, 1 superficial tearing, 2 deep tearing or maceration, and 3 complete tear or severe damage. Patient sex and BMI were recorded and compared with stem type and muscle damage scores. An ordinal logistic regression model was used for statistical analysis.ResultsAfter controlling for relevant confounding variables using logistic regression, we found that mean muscle damage was associated with male sex (0.93, SD 0.76 versus 0.70, SD 0.68; pxa0<xa00.001) and increasing BMI levels (pxa0<xa00.001). As BMI increased, more muscle damage also was found in men compared with women (pxa0=xa00.05; odds ratio [OR], 1.029; 95% confidence interval [CI], 1.000–1.060). There was no overall difference in mean muscle damage between short and standard-length stems (0.78, SD 0.77 versus 0.85, SD 0.69, pxa0=xa00.32); however, as BMI increased, less damage was seen with a short stem (pxa0=xa00.04; OR, 0.968; 95% CI, 0.931–0.997).ConclusionsVisible muscle damage occurred in most hips during anterior supine intermuscular hip arthroplasty. The clinical importance of this muscle damage requires further study, because some evidence suggests earlier restoration of gait and cessation of walking aids with direct anterior THA despite this damage; however, this was not studied here. Surgeons performing this approach can expect more difficulty and as a result possibly more damage to the TFL in patients with male sex and increased BMI. The use of a short stem can be considered for patients with increased BMI to limit damage to the TFL.Level of EvidenceLevel III, therapeutic study.

Partial two-stage exchange of the infected total hip replacement using disposable spacer moulds

The common recommended treatment for infected total hip replacement is two-staged exchange including removal of all components. However, removal of well-fixed femoral stems can result in structural bone damage. We recently reported on an alternative treatment of partial two-stage exchange used in selected cases, in which a well-fixed femoral stem was left and only the acetabular component removed, the joint space was debrided thoroughly, an antibiotic-laden polymethylmethacrylate spacer was moulded using a bulb-type syringe and placed in the acetabulum, intravenous antibiotics were administered during the interval, and delayed re-implantation was performed. In 19 patients treated with this technique from January 2000 to January 2011, 89% were free of infection at a mean follow-up of four years (2 to 11). Since then, disposable silicone moulds have become available to fabricate spacers in separate femoral and head units. The head spacer mould, which incorporates various neck taper adapter options, greatly facilitates the technique of partial two-stage exchange. We report our early experience using disposable silicone head spacer moulds for partial two-stage exchange in seven patients with infected primary hip replacements.

Unicompartmental Knee Arthroplasty: Does a Selection Bias Exist?

Unicompartmental knee arthroplasty (UKA) is a minimally invasive option reported to allow a more rapid recovery and better patient outcomes. However, whether these outcomes are related to selection bias has not been fully investigated. This study examines whether a bias existed in selection of UKA candidates. We compared outcomes of patients who were scheduled for UKA but had the plan changed intraoperatively to total knee arthroplasty (TKA) to two randomly selected contemporaneous control groups: 1) patients planned as UKA who received UKA and 2) patients planned as TKA who received TKA. Our results not only showed a selection bias existed, but also showed patients converted to TKA intraoperatively had similar clinical results to patients receiving UKAs and better results than patients originally scheduled for TKA.