Assessing Taper Geometry, Head Size, Head Material, and Their Interactions in Taper Fretting Corrosion of Retrieved Total Hip Arthroplasty Implants.

BACKGROUND: Decreased fretting and corrosion damage at the taper interface of retrieved ceramic-on-polyethylene total hip arthroplasty (THA) implants has been consistently reported; however, resultant fretting corrosion as a function of femoral head size and taper geometry has not been definitively explained. METHODS: Eight cohorts were defined from 157 retrieved THA implants based on femoral head composition (n = 95, zirconia-toughened alumina, ZTA vs n = 62, cobalt-chromium alloy, CoCr), head size (n = 56, 32mm vs n = 101, 36mm), and taper geometry (n = 84, 12/14 vs n = 73, V40). THA implants were evaluated and graded for taper fretting and corrosion. Data were statistically analyzed, including via a 23 factorial modeling. RESULTS: Factorial-based analysis indicated the significant factors related to both resultant (summed) fretting and corrosion damage were head material and taper geometry; head material-taper geometry interaction was also a significant factor in resultant corrosion damage. Lower rates of moderate-to-severe fretting and corrosion damage were exhibited on ZTA heads (ZTA = 13%, CoCr = 38%), smaller heads (32mm = 18%, 36mm = 26%), and 12/14 tapers (12/14 = 13%, V40 = 35%). ZTA+32mm heads demonstrated the lowest rates of moderate-to-severe fretting and corrosion damage (12/14 = 2%, V40 = 7%), whereas CoCr heads with V40 tapers demonstrated the greatest rates of moderate-to-severe damage (32mm = 47%, 36mm = 59%). CONCLUSION: In this series, retrieved implants with ZTA, 32-mm heads paired with 12/14 tapers exhibited lower rates of moderate-to-severe damage. Factorial analysis showed head material, taper geometry, and their interactions were the most significant factors associated with resultant damage grades. Isolating implant features may provide additional information regarding factors leading to fretting and corrosion damage in THA. LEVEL OF EVIDENCE: IV (case series).

Analysis of Retrieved Unicompartmental Knee Implants and Tissue: Third-Body Wear as a Potential Contributor to Progression of Arthritis to Adjacent Compartments.

Unicompartmental knee arthroplasty (UKA) for the treatment of single-compartment osteoarthritis has been associated with polyethylene wear and progression of osteoarthritis into adjacent compartments, leading to revision. In this study, damage and clinical failure modes of retrieved UKA implants were investigated and protein expression profiles between articular cartilage adjacent to UKA and primary osteoarthritic cartilage were compared. Fifty retrieved UKA implants were analyzed for various damage. Records review and radiographic analysis were performed to collect clinical data and implant characteristics. Cartilage harvested from revision UKA and primary total knee arthroplasty surgeries was characterized with a proteome profiling array detecting levels of 36 different cytokines, chemokines, and acute phase inflammatory proteins. Progression of osteoarthritis (n=18, 36%) and component loosening (n=17, 34%) were the most common reasons for revision. Liners exhibited the highest frequency of damage modes. Progression of arthritis positively correlated with radiographic presence of extruded bone cement and burnishing of liner components. A protein-level profile between revision UKA and primary total knee arthroplasty cartilage showed 12 differentially expressed cytokines. Failure of UKA may be secondary to the effects of wear debris particulate migration into the adjacent compartment, suggesting an additional pathway of cartilage damage manifesting as traditional clinical symptoms. [Orthopedics. 2019; 42(3):149-157.].

Intraoperative Psoas Compartment Block vs Preoperative Fascia Iliaca Block for Pain Control After Direct Anterior Total Hip Arthroplasty: A Randomized Controlled Trial.

BACKGROUND: Modern joint arthroplasty protocols place an emphasis on minimizing patient-reported postoperative pain while minimizing opioid consumption. The use of multimodal pain management protocols has been reported to improve patient outcomes and satisfaction after total hip arthroplasty. METHODS: In a prospective, single-surgeon trial, 50 patients undergoing primary direct anterior approach total hip arthroplasty were randomized to receive a preoperative fascia iliaca compartment block (FICB) or an intraoperative surgeon-delivered psoas compartment block (PCB). Patient-reported pain was recorded in the postanesthesia care unit, recovery floor and 3 weeks postoperatively. Opioid use was recorded during the hospital stay. RESULTS: Average visual analog scale pain scores in the postanesthesia care unit were 38.7 ± 8.7 vs 35.6 ± 8.3 (P = .502) for the preoperative FICB and intraoperative PCB groups, respectively. No significant difference was found between groups at the 3-week visit for postoperative pain (FICB: 2.9 ± 1.4; PCB: 3.2 ± 2.0; P = .970) and patient-reported pain satisfaction (FICB: 8.8 ± 2.2; PCB: 9.7 ± 0.6; P = .110). CONCLUSION: During the direct anterior approach for total hip arthroplasty, PCB is an effective and efficient regional anesthesia technique. It may be used to obtain satisfactory postoperative pain control and patient satisfaction while decreasing hospital resources.

Psoas Compartment Block vs Periarticular Local Anesthetic Infiltration for Pain Management After Anterior Total Hip Arthroplasty: A Prospective, Randomized Study.

BACKGROUND: The psoas compartment block (PCB) or periarticular soft-tissue local anesthetic injection are forms of regional anesthesia often used as one of the components in multimodal anesthesia applied during total hip arthroplasty (THA). The most efficacious form of regional anesthesia for THA has yet to be determined. METHODS: In a single-surgeon, prospective, clinical trial, patients undergoing THA via direct anterior approach were randomized to receive an intraoperative periarticular local anesthetic infiltration (periarticular injection) or a PCB. Postoperative pain scores, narcotic consumption, and complications were recorded. RESULTS: Forty-nine patients were randomized to the PCB and 50 were randomized to the periarticular injection. The resting pain score 3 hours postoperatively was statistically significantly lower in the periarticular injection group by 1.1 point (2.9 ± 2.2 vs 4.0 ± 2.2, P = .036). No difference was found in resting pain scores or ambulatory pain scores in the morning or evening of postoperative day 1, 2, or at the 3-week follow-up visit. There was no difference in in-hospital narcotic consumption between groups (P = 1.0). There were no major complications directly related to the block in either group. A total of 6 patients reported complaints of transient numbness, 5 in the PCB group (5/49, 10.2%), and one in the periarticular injection group (1/50, 2%, P = .087). CONCLUSION: These results demonstrate similarity between the 2 methods. We prefer periarticular anesthetic infiltration over PCB due to improved immediate postoperative pain scores and avoidance of potential symptoms associated with nerve blockade.

Fretting and Corrosion Damage in Retrieved Metal-on-Polyethylene Modular Total Hip Arthroplasty Systems: What Is the Importance of Femoral Head Size?

BACKGROUND: Fretting and corrosion at the modular femoral head-femoral neck (taper) interface have been reported in retrieved total hip arthroplasty (THA) prostheses. This study investigated associations among implant design, radiographic factors, and patient factors with corrosion and fretting at the taper interface in retrieved metal-on-polyethylene modular THA prostheses. METHODS: Ninety-two retrieved primary metal-on-polyethylene THA implants were evaluated and graded for fretting, corrosion, and damage at the taper interface, including the femoral stem trunnion and femoral head. Preoperative radiographs were assessed for osteolysis and femoral stem alignment; and medical records were reviewed for demographic data. RESULTS: Male patients had greater head corrosion (P = .037), patient age at revision had a weak, negative correlation with trunnion corrosion (ρ = -0.20, P = .04), and both body mass index and duration of implantation had weak, positive correlations with head fretting (ρ = 0.26, P = .01 and ρ = 0.33, P = .001, respectively). A weak, negative correlation was found between femoral head size and both head fretting and head corrosion (ρ = -0.26, P = .007 and ρ = -0.21, P = .028, respectively), and a weak, positive correlation was found between head offset and trunnion fretting (ρ = 0.23, P = .030). Varus femoral stem alignment was associated with greater head fretting (P = .038). CONCLUSION: Larger femoral head sizes were correlated with less severe head corrosion and head fretting, with 28-mm heads exhibiting more moderate-to-severe damage. Other factors, such as head-taper engagement and geometry, rather than head size, may affect rates of corrosion and fretting damage at the taper interface.

Increasing Liner Anteversion Decreases the Interfacial Strength of Polyethylene Liners Cemented Into Titanium-Alloy Acetabular Shells.

BACKGROUND: Acetabular component positioning during revision total hip arthroplasty can be suboptimal. Cementation of an acetabular liner into a well-fixed acetabular shell can allow surgeons to correct component version and inclination without the need for extensive revision surgery and progressive pelvic bone loss. However, to date, it is unknown what degree of version can be corrected without sacrificing fixation strength of the construct. In this study, cemented liners were biomechanically evaluated at increasing degrees of liner anteversion. METHODS: Twenty-five commercially available liners were cemented into acetabular shells at 0°, 10°, 20°, 30°, and 40° of liner anteversion, relative to the acetabular shell (n = 5 per group). Components were then fixed to a materials testing frame and evaluated via an established lever-out testing protocol. Test data were collected via test frame software for calculation of yield and maximum moments during biomechanical testing. RESULTS: When liners were cemented at 20°, 30°, and 40° of liner anteversion, a significant decrease in maximum fixation moment was found when compared liners cemented at both 0° and 10° (P < .05). A significant negative correlation was noted for both yield and maximum moments and increasing liner angle (r = -0.566; P = .011 and r = -0.604; P = .006, respectively). CONCLUSION: Biomechanical data from our study suggest that a threshold of acceptable anteversion during revision total hip arthroplasty is <20°. However, further studies are warranted to continue evaluation of the potential clinical impact and long-term device performance in this setting.

Clinical performance of a highly cross-linked polyethylene at two years in total hip arthroplasty: a randomized prospective trial.

We report the 2-year results for a prospective randomized trial comparing highly cross-linked with standard polyethylene in total hip replacements. In our study, 46 hips were available for radiographic analysis at 2- and 3-year follow-up. Femoral bearings were 28-mm cobalt chrome with the polyethylene insert randomly selected at the time of implantation to be highly cross-linked polyethylene (Crossfire; Stryker Howmedica Osteonics, Allendale, NJ) or standard polyethylene (N(2)/Vac, Stryker Howmedica Osteonics). Polyethylene wear rates were measured based on anterior-posterior (AP) and lateral pelvis radiographs at 6 weeks and at yearly intervals using a validated computer-assisted edge-detection method. Wear rates between the 2 groups were compared using the nonparametric Mann-Whitney test at the 95% level. A significant reduction in 2- and 3-dimensional linear wear rates (42% and 50%) was found in the highly cross-linked group (P =.001 and P =.005).