Factors Affecting the Length of Convalescent Hospital Stay Following Total Hip and Knee Arthroplasty

Association between Obesity and Short-Term Patient-Reported Outcomes following Total Knee Arthroplasty: A Retrospective Cohort Study in Japan

Background: This study investigated the association between obesity and short-term patient-reported outcomes after total knee arthroplasty (TKA). Methods: The primary outcomes were the Western Ontario and McMaster Universities Osteoarthritis Index's (WOMAC) pain and function scores. Data were collected preoperatively and 2 and 4 weeks after surgery. Patients were stratified into three groups based on body mass index (BMI): normal weight (BMI < 24.99 kg/m2), overweight (25 ≤ BMI < 29.99 kg/m2), and obese (BMI ≥ 30 kg/m2). The associations between BMI and the WOMAC pain and function scores were assessed using generalized linear mixed models. Results: Among the 102 patients (median age: 75.0, women [85.3%]), 29.4%, 48.0%, and 22.5% were normal weight, overweight, and obese, respectively. The mean pain and function scores at baseline were similar across the BMI-stratified groups (p = 0.727 and 0.277, respectively). The pain score significantly improved 2 weeks post-surgery (p = 0.001). The function score improved significantly 4 weeks post-surgery (p < 0.001). The group and group-by-time interaction effects lacked statistical significance. Conclusions: All patients statistically and clinically showed relevant pain reduction and functional improvement shortly after TKA, irrespective of their obesity status. These data may help healthcare professionals discuss the expectations of pain amelioration and functional improvement with TKA candidates.

Relationship between the degree of subchondral collapse and articular surface irregularities in osteonecrosis of the femoral head

Articular surface irregularities are often observed in collapsed femoral heads with osteonecrosis, while the effects of the degree of collapse on the articular surface are poorly understood. We first macroscopically assessed the articular surface irregularities on 2-mm coronal slices obtained using high-resolution microcomputed tomography of 76 surgically resected femoral heads with osteonecrosis. These irregularities were observed in 68/76 femoral heads, mainly at the lateral boundary of the necrotic region. The mean degree of collapse was significantly larger for femoral heads with articular surface irregularities than for those without (p < 0.0001). Receiver operating characteristic analysis showed that the cutoff value for the degree of collapse in femoral heads with articular surface irregularities at the lateral boundary was 1.1 mm. Next, for femoral heads with <3-mm collapse (n = 28), articular surface irregularities were quantitatively assessed based on the number of automatically counted negative curvature points. Quantitative evaluation showed that the degree of collapse was positively correlated with the presence of articular surface irregularities (r = 0.95, p < 0.0001). Histological examination of articular cartilage above the necrotic region (n = 8) revealed cell necrosis in the calcified layer and abnormal cellular arrangement in the deep and middle layers. In conclusion, articular surface irregularities of the necrotic femoral head depended on the degree of collapse, and articular cartilage was already altered even in the absence of macroscopically determined gross irregularities.

Factors affecting short-term functional gain following total knee arthroplasty in patients aged from 75 years at a postacute rehabilitation setting

The intensive rehabilitation of older patients after total knee arthroplasty (TKA) is vital for short-term improvement in mobility and daily living activities. We aimed to investigate the effectiveness of multidisciplinary rehabilitation and assess the early postoperative predictors that are associated with functional gain in TKA patients aged from 75 years in a postacute care setting. This study included 190 patients following primary TKA who were admitted at the postacute rehabilitation hospital. The main outcome measures were the motor component of functional independence measure (M-FIM), M-FIM effectiveness, numerical rating scale, knee extension strength and range of motion, 10-m walk test, Berg balance scale (BBS), and mini-mental state examination (MMSE). The functional gain between patient age groups of ≥75 (n = 105) and <75 (n = 85) years were compared. Although patients aged ≥75 years showed lower improvement in BBS score compared with <75 years, the M-FIM gains and other physical functions were similar in both age groups. In multivariate analysis, the results for M-FIM at admission (β: -0.703; P = 0.001), BBS (β: 0.342; P = 0.032) and MMSE (β: 0.446; P = 0.021) were independently associated with functional gain in the patients following TKA aged ≥75 years. Multidisciplinary inpatient rehabilitation was beneficial for basic functional gain except for improvement in balance ability in patients after TKA aged ≥75 years. Functional level, balance ability and cognitive status in the early postoperative period can be useful predictors for short-term functional gain in the postacute care phase.