Comparison of Expectations and Outcomes in Rheumatoid Arthritis Versus Osteoarthritis Patients Undergoing Total Knee Arthroplasty

BackgroundWe hypothesized that patients undergoing primary total knee arthroplasty (TKA) for rheumatoid arthritis (RA) would have different preoperative expectations compared to osteoarthritis (OA) patients, and that postoperative satisfaction would correlate with specific postoperative pain and functional domains.MethodsThis is a retrospective cohort study of RA patients matched based on age, gender, American Society of Anesthesiologists score, and Charlson Comorbidity Index score 1:2 with OA patients (76 RA, 152 OA) who underwent primary TKA. The Hospital for Special Surgery Knee Replacement Expectations Survey, Visual Analogue Scale for Pain (VAS), Knee injury and Osteoarthritis Outcome Score (KOOS), and the Short Form-12 (SF-12) were compared at baseline and at 2 years postoperatively. Minimum clinically important differences (MCIDs) were calculated for KOOS and SF-12 subdomains.ResultsPreoperatively, RA patients had lower expectations, worse VAS Pain, and worse KOOS Pain, Symptoms, and Activities of Daily Living (P < .05). However, at 2 years, RA patients had significantly larger improvements in VAS (P = .01) and these 3 KOOS subdomains (P < .05), achieving comparable absolute scores to OA patients. Overall, 86.1% of RA and 87.1% of OA patients were either somewhat or very satisfied with their TKA. Patient satisfaction correlated with VAS Pain and KOOS outcome scores in both groups. RA and OA patients had high rates of achieving MCID in SF-12 physical component scores and all 5 KOOS subdomains. A higher proportion of RA patients achieved MCID in KOOS Symptoms (98.4% vs 77.2%, P < .001).ConclusionRA patients had lower baseline expectations compared to OA patients. However, RA patients had greater improvements in KOOS and SF-12 subdomains, and there was no difference in satisfaction compared to OA patients after TKA.     

Morphometric Assessment of Resected Femoral Cut Surface in Korean Knees and Its Fitting With Western-Designed Femoral Components

BackgroundThis study aimed at assessing the morphometry of resected femurs in Korean patients during total knee arthroplasty (TKA) and comparing these measurements with current Western-designed femoral component dimensions.MethodsThis single-blind, prospective, randomized, controlled trial involved intraoperative measurements for 271 femoral component implantations from 3 contemporary TKA systems, with 2 systems offering narrow sizing options. The difference between femoral component dimensions and the resected surface of distal femur was measured in millimeters at 5 distinct zones.ResultsOverhang of standard femoral component was common in the anterior-medial condyle and anterior-lateral condyle ranging from 50.8% to 99.0% and 21.5% to 88.0%, respectively. With narrow femoral components, the rate of overhang reduced to 21.5%-30.2% and 9.2%-32.1%. Conversely, underhang rates were higher over the anterior flange width, middle medial-lateral and posterior medial-lateral zones. Standard components displayed higher underhang rates at these zones compared to narrow components. The good fit rate for femoral component was low among the 3 systems ranging from 1.0% to 56.0%. System with narrow option sizing increases the underhang rates in males, while improving the component fit among females at similar zones with rate ranging from 5.2% to 52.9%.ConclusionCurrently available TKA implant designs may not provide a perfect match for the distal femoral shape of the Korean population. The availability of implants with standard and narrow options can substantially improve the optimal fitting of femoral components in the Korean population.     

Preoperative Systemic Bone Quality Does Not Affect Tibial Component Migration in Knee Arthroplasty: A 2-Year Radiostereometric Analysis of a Hundred Consecutive Patients

BackgroundBone quality and other preoperative predictive factors may affect implant migration and the survival of knee arthroplasty.MethodsIn a prospective cohort of 100 consecutive patients (65 women) at a mean age of 67.7 years (range 39-87 years), we investigated preoperative predictors of postoperative tibial component migration in cemented and cementless total knee arthroplasties or cemented unicompartmental knee arthroplasty. Predictors consisted of Knee Injury and Osteoarthritis Outcome Score (KOOS) and Oxford Knee Score, questionnaires, bone turnover markers of CTX and P1NP, systemic bone mineral density (BMD), and knee osteoarthritis (OA) grade. Tibial component migration was measured with radiostereometry postoperative, at 1 and 2 years of follow-up.ResultsBetween 1 and 2 years, 19 tibial components migrated continuously (maximum total point motion [MTPM] > 0.2 mm). In general, there was no difference in age, body mass index, BMD, KOOSs, or OA grade between patients with continuous tibial migration compared to patients without continuous migration (P > .11). However, cementless tibial components with continuous migration had a lower KOOS pain score (more pain), lower vitamin D, and a higher bone turnover (CTX) value than patients without continuous migration. There was no association between the BMD and MTPM at 1-year follow-up regardless of prothesis type (P > .17). Patients with osteoporosis and normal BMD had similar mean tibial component MTPM at 2 years (3 prostheses combined; P = .34).ConclusionMigration of tibial components inserted with or without bone cement was not affected by the preoperative bone quality in terms of systemic BMD, bone turnover markers, and OA grade in the knee.     

Adequate Positioning of the Tibial Component Is Key to Avoiding Bearing Impingement in Oxford Unicompartmental Knee Arthroplasty

BackgroundBearing dislocation is a serious complication of unicompartmental knee arthroplasty (UKA) with the Oxford knee prosthesis equipped with a mobile bearing. We aimed to clarify the extent of intraoperative movement of the mobile bearing and its relationship with the positioning of prosthesis components in patients undergoing Oxford UKA.MethodsThis retrospective study included 50 patients (50 knees) who underwent Oxford UKA for anteromedial osteoarthritis or osteonecrosis of the knee. Intraoperative bearing movement was assessed at various angles of knee flexion (0°, 30°, 60°, 90°, and 120°). We stratified patients according to the extent of bearing movement posteriorly during intraoperative knee flexion, with or without contacting the lateral wall of the tibial component (with contact, 20 knees; without contact, 30 knees). Postoperative radiographic evaluations were conducted at 1 week postoperatively to assess the positional parameters of the tibial and femoral components (varus/valgus alignment, rotation, mediolateral position). Clinical evaluations were conducted at 1 year postoperatively (maximum flexion angle, Oxford Knee Score).ResultsAbnormal intraoperative movement of the mobile bearing resulting in contact with the lateral wall of the tibial component was associated with a significantly more medial position and external rotation of the tibial component, as well as poorer improvement in knee flexion angle at 1 year postoperatively.ConclusionIn Oxford UKA recipients, the bearing may impinge on the lateral wall of the tibial component during flexion above 60° if the tibial component is placed too medially or exhibits pronounced external rotation, which may limit knee function improvement postoperatively.     

Partial Component–Retained 2-Stage Reconstruction in the Treatment of Infected Hip Arthroplasty

BackgroundIt is considered the gold standard treatment for infected hip arthroplasty to remove and reimplant the corresponding whole set of implant components before and after infection control, but it usually causes substantial bone loss to remove the well-fixed cup or stem, which may increase the difficulty in reconstruction. We would like to determine whether infected hip arthroplasty can be treated without removal of a well-fixed cup or stem.MethodsPatients with infected hip arthroplasty and a radiographically well-fixed, cementless cup or stem were selected. During the first surgical stage, we retained the stem or cup if these cannot be removed using a stem or cup extractor. We performed the reimplantation surgery after control of infection.ResultsFrom January 2008 to December 2016, 26 patients underwent partial component–retained 2-stage reconstruction. All the patients were free of infection with a mean follow-up time of 43.85 months.ConclusionPartial component–retained 2-stage reconstruction may be a treatment option for infected total hip arthroplasty with a well-fixed component in patients.     

Quantitative measurements of hip abduction strength in lumbar surgery patients

BackgroundWe sought to evaluate the hip abduction strength in patients before and after lumbar surgery.Materials and methodsEighty-four patients (51 males and 33 females) undergoing surgery for lumbar disc herniation or lumbar canal stenosis were selected. Mean age was 64.7 ± 13.8 years. Seven patients (8.3%) had surgery at multiple levels, including L2-L3 (group A), 27 (32.1%) patients had surgery at multiple levels including L3-L4 (group B), 32 (38.1%) patients had surgery at the L4-L5 level only (group C), and 18 (21.4%) patients had surgery at the L5-S1 level only (group D). Hip abduction strength was measured in the 84 patients preoperatively and in 49 patients postoperatively.ResultsIn all patients, preoperative mean hip abduction strength on the symptomatic side and the asymptomatic side was 71.4 ± 34.5 N and 90.7 ± 36.5 N, respectively (p = 0.0008). In groups A and B, there were no significant differences between the mean hip abduction strength on the symptomatic and contralateral side. In group C, those on the symptomatic and contralateral side were 68.0 ± 33.5 N and 89.3 ± 34.8 N, respectively (p = 0.0181). In group D, those on the symptomatic and contralateral side were 74.3 ± 42.4 N and 101.7 ± 44.7 N, respectively (p = 0.0314). In the 49 patients of all groups that could be measured postoperatively, there were no significant differences between the mean hip abduction strength on both sides.ConclusionsIt was confirmed that the gluteus medius, which was main hip abductor, was mainly innervated by L5 and its mean strength significantly improved postoperatively. The possibility of improvement of hip abduction strength, especially with unchanged tibialis anterior strength, could be very useful for operative decisions.