Factors associated with the progression of sagittal spinal deformity after total hip arthroplasty: a propensity score-matched cohort study.

PURPOSE: The functional interaction between the hip and spine in patients undergoing total hip arthroplasty (THA) is clinically significant, as it impacts post-operative outcomes. Therefore, this study aimed to identify factors associated with the progression of sagittal spinal deformity and assess the association with patient-reported outcomes. METHODS: This retrospective case-control study included 200 patients who underwent primary THA and completed a mean follow-up duration of 42.2 months (range, 24.0-78.0). We employed a multivariate logistic regression to identify variables predictive of a post-THA sagittal vertical axis (SVA) ≥ 50 mm, which was indicative of a spinal sagittal imbalance. Propensity score-matched cohorts for age, sex, body mass index, follow-up duration, hip flexion contracture, developmental dysplasia, pelvic incidence (PI), and SVA were created, and the outcomes were compared between the two groups. RESULTS: PI (odds ratio 1.39; 95% confidence interval 1.04-1.86, p = 0.033) was associated with an SVA ≥ 50 mm. After successfully matching patients with (n = 50) and without (n = 50) an SVA ≥ 50 mm, the minimum clinically important difference showed significant differences between the 50 matched pairs (p = 0.016 for EuroQol-5D, p = 0.003 for Hip Disability and Osteoarthritis Outcome Score Joint Replacement, and p < 0.001 for low back pain). CONCLUSION: PI is associated with the development of a positive sagittal spinal malalignment post-THA. This finding can assist surgeons in managing patient expectations and in optimising outcomes. Feasible strategies are warranted to minimise the risk of spinal deformity progression post-THA.

The psoas muscle index as a useful predictor of total hip arthroplasty outcomes.

INTRODUCTION: The aim of this study is to assess the association between the psoas muscle index (PMI) and total hip arthroplasty (THA) outcomes. This is a critical issue as sarcopenia has been associated with poor patient satisfaction post-THA. MATERIALS AND METHODS: This was a retrospective case-control study of 205 THAs, with a mean follow-up of 3.6 (range, 2.0-5.5) years. Age, sex, serum immune markers, spinopelvic parameters, PMI (quantified as the cross-sectional area of the psoas, bilaterally, at L3 divided by the individual's height squared), and patient-reported outcomes were compared between patients 'with' (n = 118) and 'without' (n = 87) achievement of a minimum clinically important difference (MCID) improvement in the EuroQol 5-Dimension (EQ-5D), post-THA. Logistic regression and receiver operating characteristic curve analyses were used to identify predictive factors. RESULTS: A ≥ MCID improvement in the EQ-5D was associated with the PMI (odds ratio, 0.75; 95% confidence interval, 0.63-0.91; P = 0.028), prognostic nutritional index (odds ratio, 0.85; 95% confidence interval, 0.45-0.94; P = 0.043), and age (odds ratio, 1.09; 95% confidence interval, 1.01-1.18; P = 0.044). After adjusting the PMI threshold to 4.0 cm2/m2 for females and 6.4 cm2/m2 for males, there were significant differences in serum factors (P = 0.041 for albumin and P = 0.016 for a prognostic nutritional index < 40), MCID (P < 0.001 for EQ-5D, P < 0.001 for low back pain, and P = 0.008 for the Hip Disability and Osteoarthritis Outcome Score Joint Replacement score), patient satisfaction (P = 0.003), and T1 pelvic angle (P = 0.030). CONCLUSION: The PMI, which is associated with nutritional status and global sagittal spinal deformity, does predict THA outcomes. Therefore, it can be useful when discussing THA expectations with patients.

Clinical significance of relative pelvic version measurement as a predictor of low back pain after total hip arthroplasty.

PURPOSE: To evaluate the association between the preoperative global alignment and proportion (GAP) score and low back pain (LBP) after total hip arthroplasty (THA). METHODS: This was a retrospective case-control study of 200 patients who underwent primary unilateral THA for hip osteoarthritis. The following variables were compared between individuals with (n = 76) and without (n = 124) LBP after THA over a mean follow-up of 2 years: age, sex, GAP score, and patient-reported outcome measures. Logistic regression and receiver operating characteristic curve analyses were used to detect predictive factors. RESULTS: The following parameters were predictive of post-THA LBP: relative pelvic version (RPV) <-7° (odds ratio, 1.43; 95% confidence interval, 1.10-1.72; P = 0.032) and relative lumbar lordosis <-15° (odds ratio, 1.13; 95% confidence interval, 1.04-2.13; P = 0.041) preoperatively. Using an RPV cutoff value of - 7° (specificity 61/64 = 0.953; sensitivity 121/136 = 0.890), there were significant between-group differences in LBP visual analog scale (P = 0.020), Oswestry Disability Index (ODI, P = 0.014), EuroQol 5-Dimension (P = 0.027), Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS JR, P = 0.012), patient satisfaction (P = 0.024). There was clinically meaningful improvement for LBP visual analog scale (P = 0.001), ODI (P = 0.004), and HOOS JR (P < 0.001). The RPV before THA was correlated with HOOS JR (r = 0.773, P = 0.012) and ODI (r = - 0.602, P = 0.032) postoperatively. CONCLUSION: Among the GAP score, a moderate-to-severe pelvic retroversion was significantly associated with LBP post-THA. The RPV measurement may be a useful predictor of THA outcome, which may influence patient satisfaction.

T1 pelvic angle is associated with rapid progression of hip arthrosis.

PURPOSE: To evaluate the association between global spinal malalignment and rapid progression of hip arthrosis. METHODS: This was a retrospective, case-control study including 90 patients, contributing 90 hips, who underwent hemi- or total hip arthroplasty at our institution. For analysis, hips were classified into a rapid progression group, defined as ≥ 2 mm destruction of the femoral head or loss of the hip joint space within a 12-month period (n = 30), and a non-rapid progression group, defined by no observable hip disease progression over a period more than 12 months (n = 60). Logistic regression analysis identified factors that predicted rapid progression, with a receiver operating characteristic curve analysis used to confirm factors. RESULTS: Significant between-group differences were identified for the following parameters: pelvic tilt (P = 0.002, PT), sagittal vertical axis (P = 0.002, SVA), and T1 pelvic angle (P < 0.001, TPA). On multiple logistic regression, PT (P = 0.002), SVA (P = 0.002), and TPA (P < 0.001) were predictive of a rapid progression on hip arthrosis, with the area under the curve being greater for TPA than PT (P = 0.035). CONCLUSION: Global spinal alignment is associated with rapid progression of hip arthrosis. TPA could assist in identifying patients at risk for rapid progression of hip arthrosis, allowing for time management.

Biomechanical assessment of a novel meniscal scaffold compared to partial meniscectomy: A study on porcine meniscal injury.

This study aimed to investigate the appropriate size of scaffold implantation on stress distribution and evaluate its mechanical and biomechanical properties considering hydrolysis. The meniscus acts as a load distribution in the knee, and its biomechanical properties are essential for the development of the PGA scaffold. We established a novel meniscal scaffold, which consists of polyglycolic acid (PGA) covered with L-lactide-ε-caprolactone copolymer (P[LA/CL]). After 4 weeks of hydrolysis, the scaffold had a 7% volume reduction compared to the initial volume. In biomechanical tests, the implantation of scaffolds 20% larger than the circumferential and vertical defect size results in greater contact stress than the intact meniscus. In the mechanical evaluation associated with the decomposition behavior, the strength decreased after 4 weeks of hydrolysis. Meanwhile, in the biomechanical test considering hydrolysis, contact stress and area equivalent to intact were obtained after 4 weeks of hydrolysis. In conclusion, the implantation of the PGA scaffold might be a useful alternative to partial meniscectomy in terms of mechanical properties, and the PGA scaffold should be implanted up to 20% of the defect size.

The significance of the pelvic incidence measurement as a possible predictor of TKA outcome.

PURPOSE: To evaluate the association between the sagittal alignment of the pelvis and residual knee flexion contracture after total knee arthroplasty (TKA). This is important as a flexion contraction can be associated with the risk of poor outcomes and patient satisfaction after TKA. METHODS: This was a retrospective, case-control, study of 200 osteoarthritic knees, contributed by 200 patients, over a mean follow-up of 2.4 years. The following factors were compared between patients 'with' (46 knees) and 'without' (154 knees) a residual flexion contracture ≥ 10° after TKA: age, sex, pelvic incidence (PI), anterior femoral bowing, femoral component flexion angle (FFA), and patient-reported outcomes. Logistic regression and receiver operating characteristic curve analyses were used to identify predictive factors. RESULTS: The following factors were predictive of a residual flexion contracture ≥ 10°: a pelvic incidence ≥ 55° (odds ratio, 1.29; 95% confidence interval, 1.05-1.59; P = 0.031) and the FFA (odds ratio, 1.08; 95% confidence interval, 1.03-1.14; P = 0.044). A pelvic incidence cutoff of 55° yielded a significant between-group difference, with a sensitivity of 78.4% and specificity of 89.9% to differentiate a residual knee flexion contracture ≥ 10° (P = 0.001), patient satisfaction (P = 0.029), EuroQol 5-Dimension score (P = 0.028), anterior femoral curvature (P = 0.031), and Knee Injury and Osteoarthritis Outcome Score-Joint Replacement score (P = 0.046). CONCLUSION: A pelvic incidence > 55° is associated with a residual knee flexion contracture ≥ 10° after TKA. The significance of the pelvic incidence measurement as a possible predictor of TKA outcome was highlighted, including its impact on patient satisfaction. LEVEL OF EVIDENCE: III.

Impact of the Weightbearing Line on Cartilage Regeneration of the Medial Knee Compartment after Open-Wedge High Tibial Osteotomy, Based on Second-Look Arthroscopy.

OBJECTIVE: Cartilage regeneration is multifactorial. This study aimed to optimize the biomechanical factor of weightbearing loading allowing for cartilage regeneration and elucidate the association between cartilage regeneration and clinical outcomes after medial open-wedge high tibial osteotomy (OWHTO). DESIGN: This was a retrospective, observational study of 142 patients who underwent OWHTO and subsequently underwent second-look arthroscopic assessment at a single orthopedic surgery center in Japan. Clinical and radiographic outcomes were compared between patients with (group R) and without (group D) cartilage regeneration, measured using the International Cartilage Repair Society grading system and the macroscopic staging system at the time second-look arthroscopy was performed. A receiver operating characteristic curve analysis was used to determine the optimal weightbearing line ratio (WBLR) for cartilage regeneration. RESULTS: Group R included 82 knees, and group D 60 knees. The WBLR was higher in group R (60.9% ± 6.7%) than in group D (55.6% ± 7.6%) (P < 0.001) and was associated with a greater improvement in clinical outcomes, namely the Lysholm scale score and all subscales of the Knee Injury and Osteoarthritis Outcome Score (P < 0.01). The WBLR predicted cartilage regeneration with an odds ratio of 1.11 (P = 0.001) and an area under the curve of 0.718, for a WBLR value of 62%. CONCLUSIONS: A WBLR of 62% was associated with cartilage regeneration after OWHTO and high patient-reported clinical outcomes.

Unfavorable cortical hypertrophy potentially predisposes to periprosthetic "axe splitter" fracture in a collarless polished curved triple-tapered cemented stem: The time-dependent radiographic change in five SC-stem cases.

BACKGROUND: The periprosthetic fracture of cemented polished tapered stems is occasionally called a "unique" or "axe splitter" fracture. However, there has been insufficient evidence regarding the association between the radiographic findings prior to incidence and this cumbersome fracture. To determine if there are any radiographic interpretations associated with this fracture pattern, we report the five SC-stem cases with total hip arthroplasty. METHODS: We investigate the patient characteristics and serial radiographs of five fracture cases and evaluate the time-dependent specific radiographical changes around the stem between pre-arthroplasty and fracture. RESULTS: Fractures developed at 3.5-6.4 years after surgery with low-grade injury or with no particular incentive. Femoral cortical hypertrophy at the distal medial side around the stem was observed in all cases before the development of fractures, at 2-6 years after primary surgery. The duration between cortical hypertrophy appearance to the development of fracture was 0.4-3.1 years. CONCLUSIONS: The appearance of this zone-specific cortical hypertrophy might play a key role in the occurrence of periprosthetic fractures. Further studies with larger sample sizes should be conducted to elucidate this eccentric periprosthetic fracture.

Association of the Psoas Muscle Index and Sagittal Spinal Alignment With Patient-Reported Outcomes After Total Hip Arthroplasty: A Minimum 5-Year Follow-Up.

BACKGROUND: The aim of this study is to assess the association between a spinopelvic malalignment and patient-reported perception of the hip as being "artificial" after total hip arthroplasty (THA). This is a critical issue as an age-related spinopelvic mismatch has been postulated to be associated with the risk of poor outcomes after THA. METHODS: This is a retrospective case-control study of 274 THAs (244 of whom were women), with a mean follow-up of 6.2 (range 5.0-8.2) years. Hip perception was assessed by asking subjects whether their joint felt "natural" or "artificial." The association between an artificial perception and the following factors was evaluated: age, gender, psoas muscle index (PMI, cross-sectional area of bilateral psoas at L3 divided by height squared), and spinopelvic measures using logistic regression analysis. RESULTS: An artificial hip perception (130 hips, 47.4%) was associated with a lower PMI (P = .016), Hip Disability and Osteoarthritis Outcome Score Joint Replacement score (P = .035), EuroQol 5-Dimension score (P = .041), and a higher incidence of a pelvic incidence-minus-lumbar lordosis (PI-LL) mismatch >10° (P < .001). A flatback deformity (odds ratio 2.24, 95% confidence interval 1.22-6.31, P = .001) and PMI (odds ratio 0.61, 95% confidence interval 0.34-0.82, P = .012) were predictive of an artificial perception. With the threshold of PI-LL set to 10°, PMI (P = .034), Hip Disability and Osteoarthritis Outcome Score Joint Replacement score (P < .001), joint perception (P = .020), EuroQol 5-Dimension score (P = .028), pain (P = .031), and satisfaction (P < .001) differed between the 2 groups. CONCLUSION: A flatback deformity is associated with the risk of an artificial perception post-THA, especially in patients with sarcopenia. PMI and PI-LL measurements may help predict THA outcomes.

Three-dimensional transfer of tibial tuberosity for patellar instability with patella alta preserves patellar position and clinical outcomes: A minimum 3-year follow-up study.

BACKGROUND: The three-dimensional (3D) transfer of tibial tuberosity has been reported to improve patellofemoral congruity and showed good clinical outcomes during the short follow-up, however, little is known about whether the patellar position and clinical outcomes are preserved at longer follow-ups and the risk factors for poor clinical outcomes. HYPOTHESIS: We hypothesized that patellar position and clinical outcomes would be preserved and the predisposing factors were associated with poor clinical outcomes after the 3D transfer of tibial tuberosity. PATIENTS AND METHODS: Thirty-nine patients, with a mean age of 27.9 (15-52) years, who underwent the 3D transfer of the tibial tuberosity were enrolled. Patellar position was evaluated using the Caton-Deschamps index and patellar tilt. Clinical outcomes were evaluated with Lysholm and Kujala scores pre- and postoperatively. Age, body mass index (BMI), radiographic measurements, and range of motion (ROM) were compared between the poor group (defined as <80 points on Kujala score) and the good group (≥80 points). The mean follow-up period was 54.1 (36-100) months. RESULTS: Patellar position decreased from 1.32 (1.21-1.53) preoperatively to 0.99 (0.84-1.07) at the final follow-up, according to the Caton-Deschamps index (p < 0.01). The mean patellar tilt decreased from 26.0° (21-40°) to 15.1° (5-28°) (p < 0.01). Kujala and Lysholm scales improved from 59.1 to 54.2 to 90.1 and 91.8 at final follow-up, respectively (p < 0.01). Increased BMI, lower femorotibial angle, limited ROM, and poor preoperative clinical outcomes were the predicting factors for poor postoperative clinical outcomes (p < 0.05). CONCLUSION: The 3D transfer for patellar instability with patella alta preserved the patellar position and clinical outcomes for at least 3 years. Predisposing factors that may potentially affect postoperative clinical outcomes of the 3D transfer of tibial tuberosity include an increased BMI, valgus knee, limited ROM, and poor preoperative clinical outcomes.

Spinopelvic mismatch is associated with patient-reported outcome measures after total knee arthroplasty at a mean follow-up of 15 years.

BACKGROUND: Total knee arthroplasty (TKA) is widely performed; yet, up to 25% of patients are dissatisfied with outcomes. Our aim was to evaluate the association between a spinopelvic mismatch and patient-reported outcomes after TKA. METHODS: This was a retrospective study of 101 TKAs performed for osteoarthritis, at a mean 14.6 (range, 10.0-18.0) years post-surgery. Postoperative knee joint perception was evaluated as 'artificial', with or without restrictions, or 'natural'. Age, sex and the spinopelvic mismatch were compared between the 'artificial' (n = 54) and 'natural' (n = 47) perception groups. Multiple logistic regression analysis was used to identify predictive factors of an artificial perception, with a receiver operating characteristic curve to identify cut-off values for significant factors. RESULTS: A spinopelvic mismatch, defined as a pelvic incidence minus lumbar lordosis (PI-LL) ≥ 10°, was associated with an artificial perception (odds ratio, 1.57; 95% confidence interval, 1.29-3.22; P = 0.023). An artificial joint perception was related to lower Knee Injury and Osteoarthritis Outcome Score-Joint Replacement (KOOS-JR, P = 0.021) and EuroQol 5-Dimension (EQ-5D, P = 0.025) scores. The cut-off PI-LL of 11° differentiated the groups with a sensitivity of 87.0% and specificity of 91.9%. Postoperative KOOS-JR (P < 0.001), EQ-5D (P = 0.014), satisfaction (P = 0.015), knee extension angle (P = 0.024), and perception (P = 0.032) differed between the groups when the PI-LL threshold was set at 10°. CONCLUSION: A spinopelvic mismatch (PI-LL ≥ 10°) is associated with a risk of artificial perception of function after TKA. Measurement of the PI-LL could assist patients and surgeons to predict TKA outcomes.

Progression of pelvic retroversion is a critical factor for clinical outcome after Opening-wedge high tibial osteotomy among elderly patients.

PURPOSE: To evaluate the clinical outcome after opening-wedge high tibial osteotomy (OWHTO) and to determine the critical factors for a poor clinical outcome after OWHTO in patients aged over 65 years. METHODS: Our retrospective analysis was based on the data from 233 patients who underwent OWHTO for medial compartment knee OA at our institution between January 2013 and December 2018, and 88 patients (36 men and 52 women) over 65 years of age were included in this study. Radiographic parameters of weight-bearing line ratio (WBLR) and pelvic inclination (PI); the knee function, range of motion (ROM) and extension; and clinical outcome with Lysholm score were obtained preoperatively and postoperatively at the final follow-up visit. To evaluate the critical factors for the clinical outcome, univariate regression analysis was used to identify the relationship between postoperative and improved Lysholm score and pre-and post-operative essential factors. To reveal the factor having a greater impact on the clinical outcome, a p < 0.05 in univariate factors was entered into a multivariate regression analysis. RESULTS: The preoperative WBLR was significantly changed, and Lysholm score improved from 59.5 to 81.5 (p < 0.0001), whereas the PI, knee extension and ROM were not changed after OWHTO. Regarding the essential factors affecting clinical outcome after OWHTO, age and delta PI were negative, whereas preoperative WBLR, postoperative ROM, especially extension, had a positive effect (p < 0.05). Furthermore, only delta PI had affected the improvement of clinical outcome with OWHTO (p < 0.01), and postoperative knee extension was negatively correlated with the progression of pelvic retroversion (p < 0.01). CONCLUSION: Age at surgery and progression of pelvic retroversion were the critical factors for poor postoperative clinical outcomes after OWHTO. Care should be taken for the progression of pelvic retroversion after OWHTO because it deteriorates the clinical outcome by inducing the knee flexion contracture as the compensatory mechanism for the balance of sagittal alignment.

Assessing primary and bacterial production rates in biofilms on pebbles in Ishite stream, Japan.

Various measurements of microbial productivity in streambed pebble biofilms were analyzed almost monthly for 1 year to quantify the importance of primary production as an autochthonous source of organic matter utilized to support heterotrophic bacterial production in the dynamic food web within this natural microbial habitat. Bacterial density varied from 0.3x10(8) to 1.4x10(8) cells cm-2, and chlorophyll a concentration ranged from 0.7 to 25.9 microg cm-2, with no coupled oscillation between seasonal changes in these two parameters. In bottle incubation experiments, the instantaneous bacterial growth rate of bacteria was significantly correlated with their production rate [measured by frequency of dividing cells (FDC)] as follows: ln mu=0.138FDC-3.003 (n=15, r2=0.445, p<0.001). FDC values in the pebble biofilms increased with fluctuations during the study period, ranging from 3.6% to 9.2%. Bacterial production rates largely fluctuated between 0.15 to 0.92 microg C cm-2 h-1, and its seasonal pattern was similar to that of bacterial density. Net primary production measured between May 2002 to November 2002 attained minimum level (0.5 microg C cm-2 h-1) in June and maximum level (1.9 microg C cm-2 h-1) in August. Percentages of bacterial production to net primary production ranged between 21% and 120%. Because this ratio extends both below and above 100% for these parameters, it is likely that both autochthonous and allochthonous supplies of organic matter are important for production of bacteria in the pebble biofilms that develop in rapidly flowing fresh water streams.