Mechanical and Structural Properties of Articular Cartilage and Subchondral Bone in Human Osteoarthritic Knees.

Knee osteoarthritis (OA), characterized by multiple joint tissue degenerations, remains a significant clinical challenge. Recent evidence suggests that crosstalk within the osteochondral unit may drive OA progression. While structural-biomechanical properties of bone and cartilage have been studied, potential interaction within the osteochondral unit in the context of OA has yet to be investigated. We performed comprehensive structural and biomechanical quantification of the cartilage, subchondral bone plate, and subchondral trabecular bone using 101 osteochondral cores collected from tibial plateaus of 12 control human cadavers (CT, 5 male/7 female) and 19 patients undergoing total knee replacement (OA, 6 male/13 female). For each sample, we quantified subchondral bone plate microstructure, plate-and-rod morphological properties of the subchondral trabecular bone using individual trabecula segmentation, and morphological and compositional properties of the articular cartilage. We also performed indentation testing on each compartment of the osteochondral unit to extract the respective structural-mechanical properties. Cartilage thickness was lower in moderate and severe OA regions, while OARSI score was higher only in severe OA regions. GAG content did not change in any OA region. Aggregate and shear moduli were lower only in severe OA regions, while permeability was lower only in moderate OA regions. In the subchondral bone plate, thickness and TMD were higher in moderate and severe OA regions. Tissue modulus of subchondral trabecular bone was lower in moderate OA regions despite a thicker and more mineralized subchondral bone plate; this deterioration was not observed in severe OA regions. Regression analysis revealed strong correlations between cartilage and subchondral trabecular bone properties in CT; these correlations were also found in moderate OA regions but were not observed in severe OA regions. In summary, our findings comprehensively characterize the human OA osteochondral unit. Importantly, uncoupling cartilage and subchondral bone structural-mechanical properties may be a hallmark of OA.

Knee osteoarthritis (OA) is a complex condition involving the degradation of joint tissues. To better understand OA progression, we investigated the interplay between different components of the joint. Our study focused on how cartilage, subchondral bone plate, and subchondral trabecular bone interact in human knee OA samples. We observed distinct changes in these tissues in moderate and severe OA regions compared to healthy joints. In moderate to severe OA, we found that cartilage thickness decreased while the subchondral bone plate thickened. Interestingly, the strength of the subchondral trabecular bone decreased only in moderate OA regions, not in severe OA. Moreover, our analysis revealed strong correlations between cartilage and subchondral trabecular bone properties in healthy joints and moderate OA regions. However, these correlations were absent in severe OA regions, indicating a disruption in the usual relationship between these tissues. Overall, our findings shed light on the structural and biomechanical changes occurring within the knee joint in OA. Understanding these changes may offer insights into potential therapeutic strategies for managing OA.

Cost-Effectiveness of Closed Incision Negative Pressure Therapy for Surgical Site Management After Revision Total Knee Arthroplasty: Secondary Analysis of a Randomized Clinical Trial.

BACKGROUND: The PROMISES (Post-market, Randomized, Open-Label, Multicenter, Study to Evaluate the Effectiveness of Closed Incision Negative Pressure Therapy Versus Standard of Care Dressings in Reducing Surgical Site Complications in Subjects With Revision of a Failed Total Knee Arthroplasty) randomized controlled trial compared closed incision negative pressure therapy (ciNPT) to standard of care (SOC) after revision total knee arthroplasty in high-risk patients. We assessed the costs associated with 90-day surgical site complications (SSCs) to determine the cost-benefit of ciNPT. METHODS: A health economic model was used to determine mean per-patient costs to manage the surgical site, including the costs of postoperative dressings, surgical and non-surgical interventions, and readmission. A subanalysis was performed to examine cost-benefit in "lower risk" (Charlson Comorbidity Index < 2) and "higher risk" (Charlson Comorbidity Index ≥ 2) patients. RESULTS: Patients with ciNPT experienced fewer SSCs (3.4% vs 14.3%; P = .0013) and required fewer surgical (0.7% vs 4.8%; P = .0666) and non-surgical (2.7% vs 12.9%; P = .0017) interventions compared to those with SOC. Readmission rates were significantly higher when patients experienced SSC (31% vs 4%; P = .0001). Using the economic model, respective per-patient costs for the ciNPT and SOC groups were $666 and $52 for postoperative dressings, $135 and $994 for surgical interventions, $231 and $970 for readmissions, and $15 and $70 for non-surgical interventions. Total per-patient costs for surgical site management were $1,047 for ciNPT and $2,036 for SOC. Among the lower risk population, mean per-patient cost was $1,066 for ciNPT and $1,474 for SOC. Among the higher risk population, mean per-patient cost was $676 for ciNPT and $3,212 for SOC. CONCLUSION: Despite higher upfront costs for postoperative dressings, ciNPT was cost-effective in this health economic model, decreasing the costs of surgical site management after revision total knee arthroplasty by 49% in this study population and 79% in higher risk subgroup.

The Effectiveness of Closed-Incision Negative-Pressure Therapy Versus Silver-Impregnated Dressings in Mitigating Surgical Site Complications in High-Risk Patients After Revision Knee Arthroplasty: The PROMISES Randomized Controlled Trial.

BACKGROUND: Revision total knee arthroplasty (rTKA) is associated with significant risk of wound-related morbidity. The present study aimed to evaluate the 1) efficacy of closed-incision negative-pressure therapy (ciNPT) vs silver-impregnated antimicrobial dressing (AMD) in mitigating postoperative surgical site complications (SSCs), 2) the effect of ciNPT vs AMD on certain postoperative health utilization parameters, and on 3) patient-reported outcomes (PROs) improvement at 90-day postoperative follow-up. METHODS: This multicenter randomized controlled trial was conducted between December 2017 and August 2019. Patients ≥22 years, at high risk for SSC, and receiving rTKA with full exchange and reimplantation of new prosthetic components or open reduction and internal fixation of periprosthetic fractures were screened for inclusion. Eligible patients were randomized to receive a commercially available ciNPT system or a silver-impregnated AMD (n = 147, each) for minimum of 5-day duration. Primary outcome was the 90-day incidence of SSCs with stratification in accordance with revision type (aseptic/septic). Secondary outcomes were the 90-day health care utilization parameters (readmission, reoperation, dressing changes, and visits) and PROs. RESULTS: Of 294 patients randomized (age: 64.9 ± 9.0 years, female: 59.6%), 242 (82.0%) patients completed the study (ciNPT: n = 124; AMD: n = 118). The incidence of 90-day SSCs was lower for the ciNPT cohort (ciNPT: 3.4% vs AMD: 14.3%; odds ratio (OR): 0.22, 95% confidence interval (0.08, 0.59); P = .0013). Readmission rates (3.4% vs 10.2%, OR: 0.30(0.11, 0.86); P = .0208) and mean dressing changes (1.1 ± 0.3 vs 1.3 ± 1.0; P = .0003) were lower with ciNPT. The differences in reoperation rates, number of visits, and PRO improvement between both arms were not statistically significant (P > .05). CONCLUSION: ciNPT is effective in reducing the 90-day postoperative SSCs, readmission, and number of dressing changes after rTKA. Recommending routine implementation would require true-cost analyses.

Operative Duration and Short-Term Postoperative Complications after Unicompartmental Knee Arthroplasty.

BACKGROUND: Prolonged operative duration is an independent risk factor for postoperative complications in many orthopedic procedures ranging from shoulder arthroscopy to total hip and knee arthroplasties. It has not been well studied in unicompartmental knee arthroplasty (UKA). The purpose of this study is to assess the effect of operative duration on complications after UKA. METHODS: Using the American College of Surgeons National Surgical Quality Improvement Program registry, we identified all primary unilateral UKAs from 2005 to 18. Patients were divided into three cohorts based on the operative duration: < 90 minutes, between 90 and 120 minutes, and >120 minutes. Baseline patient and operative demographics (age, gender, etc.) and thirty-day complications were compared using bivariate analysis. Multivariate analysis was used to assess the independent effect of operative duration on postoperative outcomes after adjusting for differences in baseline characteristics. RESULTS: We identified 11,806 patients who underwent primary UKA from 2005 to 18. There was no difference in the "any complication" rate between cohorts. However, operative duration >120 minutes was associated with a significantly higher likelihood of reoperation (odds ratio [OR] 2.02, 95% confidence interval [CI]: 1.15-3.57, P = .015), non-home discharge (OR: 2.14, CI: 1.65-2.77, P < .001), surgical site infection (OR: 1.76, CI: 1.03-3.01, P = .038), and blood transfusions (OR: 3.23, CI: 1.44-7.22, P = .004) when compared with operative duration <90 minutes. There was no difference in mortality rates. CONCLUSION: Increased operative duration greater than 2 hours in primary UKA is associated with an increased risk of non-home discharge, surgical site infection, reoperation, and blood transfusion.

Should Cannabinoids Be Added to Multimodal Pain Regimens After Total Hip and Knee Arthroplasty?

BACKGROUND: This study investigated the effects of dronabinol on pain, nausea, and length of stay following total joint arthroplasty (TJA). METHODS: We retrospectively compared 81 consecutive primary TJA patients who received 5 mg of dronabinol twice daily in addition to a standard multimodal pain regimen with a matched cohort of 162 TJA patients who received only the standard regimen. A single surgeon performed all surgeries. Patient demographics, length of stay, opioid morphine equivalents (MEs) consumed, reports of nausea/vomiting, discharge destination, distance walked in physical therapy, and visual analog scale pain scores were collected for both groups. Student's t-tests as well as chi-square or Mann-Whitney U-tests were used for statistical comparisons. RESULTS: There were no significant differences between the 2 groups for age, gender, body mass index, American Society of Anesthesiologists score, anesthesia type, visual analog scale scores, distance walked with physical therapy, discharge disposition, or episodes of nausea/vomiting. The mean length of stay in the dronabinol group was significantly shorter at 2.3 ± 0.9 days versus 3.0 ± 1.2 days in the control group (P = .02). In the context of a shorter stay, the dronabinol group consumed significantly fewer total MEs (252.5 ± 131.5 vs 313.3 ± 185.4 mg, P = .0088). Although the dronabinol group consumed fewer MEs per day and per length of stay on average, neither of these achieved statistical significance. No side effects of dronabinol were reported. CONCLUSION: These findings suggest that further investigation into the role of cannabinoid medications for non-opioid pain control in the post-arthroplasty patient may hold merit.

Decreased risk of knee buckling with adductor canal block versus femoral nerve block in total knee arthroplasty: a retrospective cohort study.

BACKGROUND: Femoral nerve (FNB) and adductor canal blocks (ACB) are used in the setting of total knee arthroplasty (TKA), but neither has been demonstrated to be clearly superior. Although dynamometer studies have shown ACBs spare perioperative quadriceps function when compared to FNBs, ACBs have been widely adopted in orthopaedic surgery without significant evidence that they decrease the risk of perioperative falls. METHODS: All patients who received single-shot FNB (129 patients) or ACB (150 patients) at our institution for unilateral primary TKA from April 2014 to September 2015 were retrospectively reviewed for perioperative falls or near-falls during physical therapy and inpatient care. RESULTS: There were significantly more "near-falls" with documented episodes of knee buckling in the FNB group (17 vs 3, P = .0004). These patients' first buckling episode occurred at an average of 21.1 hours postoperatively (standard deviation 5.83, range 13.83-41.15). There were no significant differences in pain scores between the 2 groups at any of the time periods measured; however, patients in the FNB group consumed significantly fewer opioids on postoperative day 1 than the ACB group (59 morphine equivalents vs 73, P = .004). CONCLUSIONS: A significantly higher rate of near-falls with knee buckling during in-hospital physical therapy was discovered in the FNB group. With increasing numbers of TKAs being performed on a "fast-track" discharge model, these results must be seriously considered, particularly in patients planning to go home the same day, to reduce the risk of postoperative falls. These data support the recent clinical data trend favoring ACB over FNB in orthopaedic surgery.

Diagnosis and Treatment of Adverse Local Tissue Reactions at the Head-Neck Junction.

Modular junctions in total hip arthroplasty are susceptible to mechanically assisted crevice corrosion, leading to the release of metal wear debris. Adverse local tissue reactions result from an immune-mediated biological reaction to this debris and can have a profound effect on the surrounding periarticular soft tissue envelope. Patients often present with pain or muscle weakness and demonstrate elevated serum cobalt and chromium levels. Serum inflammatory markers and synovial fluid tests help distinguish these reactions from deep infection in the majority of cases; however, the presence of amorphous material or fragmented cells can lead to difficulty in some cases. Advanced cross-sectional imaging is essential in establishing the diagnosis. Early revision surgery is generally the treatment of choice for symptomatic adverse local tissue reaction from corrosion at the modular head-neck junction. The existing stem is retained, and a new ceramic head is placed on the existing trunnion whenever possible. This strategy generally leads to short-term improvement of symptoms with reliable clinical outcomes; however, longer term results are presently lacking.