Aims

There is an increasing demand for hip arthroplasty in China. We aimed to describe trends in in-hospital mortality after this procedure in China and to examine the potential risk factors.

Patients and methods

We included 210 450 patients undergoing primary hip arthroplasty registered in the Hospital Quality Monitoring System in China between 2013 and 2016. In-hospital mortality after hip arthroplasty and its relation to potential risk factors were assessed using multivariable Poisson regression.

Results

During the study period, 626 inpatient deaths occurred within 30 days after hip arthroplasty. Mortality decreased from 2.9% in 2013 to 2.6% in 2016 (p for trend = 0.02). Compared with their counterparts, old age, male sex, and divorced or widowed patients had a higher rate of mortality (all p < 0.05). Risk ratio (RR) for mortality after arthroplasty for fracture was two-fold higher (RR 2.0, 95% confidence interval (CI) 1.5 to 2.6) than that for chronic disease. RRs for mortality were 3.3 (95% CI 2.7 to 3.9) and 8.2 (95% CI 6.5 to 10.4) for patients with Charlson Comorbidity Index (CCI) of 1 to 2 and CCI ≥ 3, respectively, compared with patients with CCI of 0. The rate of mortality varied according to geographical region, the lowest being in the East region (1.8%), followed by Beijing (2.1%), the North (2.9%), South-West (3.6%), South-Central (3.8%), North-East (4.1%), and North-West (5.2%) regions.

Conclusion

While in-hospital mortality after hip arthroplasty in China appears low and declined during the study period, discrepancies in mortality after this procedure exist according to sociodemographic factors. Healthcare resources should be allocated more to underdeveloped regions to further reduce mortality. Cite this article: Bone Joint J 2019;101-B:1209-1217.

Objective

High knee extensor strength may be important to protect against the development of knee osteoarthritis (OA) in populations at elevated risk, such as individuals with meniscal pathology. We investigated the extent to which high knee extensor muscle strength was associated with a decreased risk of developing radiographic or symptomatic knee OA in individuals with medial meniscal pathology.

Methods

We studied knees that at the baseline visit of the Multicenter Osteoarthritis Study had medial meniscal pathology but did not have radiographic knee OA (373 knees in 373 participants) or symptomatic knee OA (combination of radiographic knee OA and frequent knee symptoms; 531 knees in 531 participants). Isokinetic knee extensor strength was measured at baseline, and participants were followed for development of incident radiographic knee OA or incident symptomatic knee OA at 84 months. Separate binomial regression analyses with robust SEs adjusted for age, history of knee surgery, physical activity level, and clinic site were conducted for men and women.

Results

High knee extensor strength (normalized by allometric scaling) was associated with a reduced risk of radiographic knee OA in women (relative risk [RR] 0.52, 95% confidence interval [95% CI] 0.29-0.94) but not in men (RR 0.56, 95% CI 0.27-1.16). High knee extensor strength did not protect against the development of symptomatic knee OA, either in women or men.

Conclusion

The results only partly confirm the hypothesis that high knee extensor muscle strength protects against later development of knee OA in individuals with medial meniscal pathology.

Objective

Synovitis is thought to be a secondary phenomenon in the osteoarthritis (OA) process and the menisci might be triggers of localized synovitis. The aim was to assess the cross-sectional associations of posterior horn meniscal damage with perimeniscal synovitis, and with synovitis posterior to the posterior cruciate ligament (PCL) using contrast enhanced (CE) MRI.

Design

The Multicenter Osteoarthritis (MOST) Study is a longitudinal observational study of subjects with or at risk for knee OA. Subjects are a subset of MOST who were examined with 1.5T CE MRI and had semiquantitative synovitis (scored from 0 to 2 at 11 locations) and meniscal readings (scored with WORMS from 0 to 4) available. Logistic regression was used to assess the association of posterior meniscal damage and perimeniscal synovitis in the same compartment, and between posterior meniscal damage and synovitis posterior to the PCL.

Results

Three hundred and seventy seven knees were included (mean age 61.1 years±6.9, mean BMI 29.6±4.9, 44.3% women). The odds for ipsi-compartmental perimeniscal synovitis were increased for knees with medial posterior horn meniscal damage (adjusted odds ratio [aOR] 2.5, 95% confidence intervals [95% CI] 1.3,4.8), but not for lateral damage (aOR 1.7, 95% CI 0.4,6.6). No positive associations were found for meniscal damage and presence of synovitis posterior to the PCL (aOR 0.9, 95% CI 0.6,1.5).

Conclusions

Meniscal damage of the posterior horns is associated with ipsi-compartmental perimensical synovitis. No associations were found for posterior horn meniscal damage with synovitis posterior to the PCL, which suggests that synovitis posterior to the PCL is likely to be triggered by different pathomechanisms.

Purpose

To assess the associations of meniscal tears, knee mal-alignment, cartilage damage, knee effusion, and body mass index with meniscal extrusion.

Materials and methods

The Multicenter Osteoarthritis study is an observational study of individuals who have or are at risk for knee osteoarthritis (OA). The HIPAA-compliant protocol was approved by the institutional review boards of all participating centers, and written informed consent was obtained from all patients. All subjects with available baseline knee radiographs and magnetic resonance (MR) images were included. MR imaging assessment of meniscal morphologic characteristics, meniscal position, and cartilage morphologic characteristics with use of the Whole-Organ Magnetic Resonance Imaging Score system was performed by two musculoskeletal radiologists. Cross-sectional associations of severity of meniscal tears, knee malalignment, tibiofemoral cartilage damage, knee effusion, and body mass index with meniscal extrusion were assessed by using logistic regression, with multiadjustments when testing each predictor.

Results

A total of 1527 subjects (2131 knees; 2116 medial and 2106 lateral menisci) were included. Medially, meniscal tears, varus malalignment, and cartilage damage were associated with meniscal extrusion, with odds ratios (ORs) of 6.3 (95% confidence interval [CI]: 5.0, 8.0), 1.3 (95% CI: 1.1, 1.7), and 1.8 (95% CI: 1.4, 2.2), respectively. Laterally, meniscal tears, valgus malalignment, and cartilage damage were associated with meniscal extrusion, with ORs of 10.3 (95% CI: 7.1, 14.9), 2.2 (95% CI: 1.5, 3.2), and 2.0 (95% CI: 1.3, 2.9), respectively.

Conclusion

Meniscal tears are not the only factors associated with meniscal extrusion; other factors include knee malalignment and cartilage damage. Meniscal extrusion is probably an effect of the complex interactions among joint tissues and mechanical stresses involved in the OA process.

Purpose

To assess the association of meniscal root tear with the development or worsening of tibiofemoral cartilage damage.

Materials and methods

Institutional review board approval and written informed consent from all subjects were obtained. A total of 596 knees with radiographically depicted osteoarthritis were randomly selected from the Multicenter Osteoarthritis study cohort. Cartilage damage was semiquantitatively assessed by using the Whole-Organ Magnetic Resonance Imaging Score (WORMS) system (grades 0-6). Subjects were separated into three groups: root tear only, meniscal tear without root tear, and neither meniscal nor root tear. A log-binomial regression model was used to calculate the relative risks for knees to develop incident or progressing cartilage damage in the root tear group and the meniscal tear group, with the no tear group serving as a reference.

Results

In the medial tibiofemoral joint, there were 37 knees with isolated medial posterior root tear, 294 with meniscal tear without root tear, and 264 without meniscal or root tear. There were only two lateral posterior root tears, and no anterior root tears were found. Thus, the focus was on the medial posterior root tear. The frequency of severe cartilage damage (WORMS ≥ 5) was higher in the group with root tear than in the group without root or meniscal tear (76.7% vs 19.7%, P < .0001) but not in the group with meniscal but no root tear (76.7% vs 65.2%, P = .055). Longitudinal analyses included 33 knees with isolated medial posterior root tear, 270 with meniscal tear, and 245 with no tear. Adjusted relative risk of cartilage loss was 2.03 (95% confidence interval [CI]: 1.18, 3.48) for the root tear group and 1.84 (95% CI: 1.32, 2.58) for the meniscal tear group.

Conclusion

Isolated medial posterior meniscal root tear is associated with incident and progressive medial tibiofemoral cartilage loss.

Objective

To study the effect of valgus malalignment on knee osteoarthritis (OA) incidence and progression.

Methods

We measured the mechanical axis from long limb radiographs from the Multicenter Osteoarthritis Study (MOST) and the Osteoarthritis Initiative (OAI) to define limbs with valgus malalignment (mechanical axis of ≥1.1° valgus) and examined the effect of valgus alignment versus neutral alignment (neither varus nor valgus) on OA structural outcomes. Posteroanterior radiographs and knee magnetic resonance (MR) images were obtained at the time of the long limb radiograph and at followup examinations. Lateral progression was defined as an increase in joint space narrowing (on a semiquantitative scale) in knees with OA, and incidence was defined as new lateral narrowing in knees without radiographic OA. We defined lateral cartilage damage and progressive meniscal damage as increases in cartilage or meniscus scores at followup on the Whole-Organ Magnetic Resonance Imaging Score scale (for the MOST) or the Boston Leeds Osteoarthritis Knee Score scale (for the OAI). We used logistic regression with adjustment for age, sex, body mass index, and Kellgren/Lawrence grade, as well as generalized estimating equations, to evaluate the effect of valgus alignment versus neutral alignment on disease outcomes. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs).

Results

We studied 5,053 knees (881 valgus) of subjects in the MOST cohort and 5,953 knees (1,358 valgus) of subjects in the OAI cohort. In both studies, all strata of valgus malalignment, including 1.1° to 3° valgus, were associated with an increased risk of lateral disease progression. In knees without radiographic OA, valgus alignment >3° was associated with incidence (e.g., in the MOST, adjusted OR 2.5 [95% CI 1.0-5.9]). Valgus alignment >3° was also associated with cartilage damage on MR imaging in knees without OA (e.g., in the OAI, adjusted OR 5.9 [95% CI 1.1-30.3]).We found a strong relationship of valgus malalignment with progressive lateral meniscal damage.

Conclusion

Valgus malalignment increases the risk of knee OA radiographic progression and incidence as well as the risk of lateral cartilage damage. It may cause these effects, in part, by increasing the risk of meniscal damage.