Cartilage Restoration for Tibiofemoral Bipolar Lesions Results in Promising Failure Rates: A Systematic Review

Donor-recipient age- or sex-mismatched osteochondral allografts do not adversely affect cumulative graft survival rates after transplantation in the knee

BACKGROUND

Osteochondral allograft transplantation (OCAT) can be performed without the need for blood-type matching or anti-rejection medications. However, other donor-recipient mismatch variables could influence outcomes. Therefore, it is critical to examine the impacts of sex and age mismatching on functional OCA survival.

METHODS

Prospectively collected data for patients undergoing primary knee OCAT enrolled in a lifelong outcomes registry were analyzed for functional OCA survival based on sex- and age-matched and -mismatched cohorts. Treatment failure was defined as the need for OCAT revision surgery or knee arthroplasty.

RESULTS

162 donor-recipient pairs were analyzed; 57 (35.2%) were sex-mismatched and 89 (54.9%) were age-mismatched. Sex-mismatched OCATs were not associated with a significantly different cumulative graft survival rate when compared to sex-matched OCATs (78.9% vs 75.2% p = 0.324). Age-mismatched OCATs were not associated with a significantly different cumulative graft survival rate when compared to age-matched OCATs (71.6% vs 81.5% p = 0.398). When adjusting for sex, BMI, concomitant procedures, and surgery type, age-mismatched and sex-mismatched OCATs were not significantly associated with higher likelihood for treatment failure.

CONCLUSION

By analyzing functional graft survival rates for donor-recipient sex- or age-mismatched OCAs following primary OCAT, the results of the present study support current donor-recipient matching protocols for OCA transplantation in the knee. Based on current evidence, donor-recipient blood-type, sex-, and age-matching are not required for safe and effective primary OCAT in the knee. However, further studies are imperative for defining modifiable variables that further optimize safety and outcomes while maximizing donor tissue quality, availability, access, and use.

Tribomechanical Properties of PVA/Nomex® Composite Hydrogels for Articular Cartilage Repair

Due to the increasing prevalence of articular cartilage diseases and limitations faced by current therapeutic methodologies, there is an unmet need for new materials to replace damaged cartilage. In this work, poly(vinyl alcohol) (PVA) hydrogels were reinforced with different amounts of Nomex® (known for its high mechanical toughness, flexibility, and resilience) and sterilized by gamma irradiation. Samples were studied concerning morphology, chemical structure, thermal behavior, water content, wettability, mechanical properties, and rheological and tribological behavior. Overall, it was found that the incorporation of aramid nanostructures improved the hydrogel's mechanical performance, likely due to the reinforcement's intrinsic strength and hydrogen bonding to PVA chains. Additionally, the sterilization of the materials also led to superior mechanical properties, possibly related to the increased crosslinking density through the hydrogen bonding caused by the irradiation. The water content, wettability, and tribological performance of PVA hydrogels were not compromised by either the reinforcement or the sterilization process. The best-performing composite, containing 1.5% wt. of Nomex®, did not induce cytotoxicity in human chondrocytes. Plugs of this hydrogel were inserted in porcine femoral heads and tested in an anatomical hip simulator. No significant changes were observed in the hydrogel or cartilage, demonstrating the material's potential to be used in cartilage replacement.

Knee Joint Preservation in Tactical Athletes: A Comprehensive Approach Based upon Lesion Location and Restoration of the Osteochondral Unit

The unique physical demands of tactical athletes put immense stress on the knee joint, making these individuals susceptible to injury. In order to ensure operational readiness, management options must restore and preserve the native architecture and minimize downtime, while optimizing functionality. Osteochondral lesions (OCL) of the knee have long been acknowledged as significant sources of knee pain and functional deficits. The management of OCL is predicated on certain injury characteristics, including lesion location and the extent of subchondral disease. Techniques such as marrow stimulation, allograft and autologous chondrocyte implantation are examined in detail, with a focus on their application and suitability in tactical athlete populations. Moreover, the restoration of the osteochondral unit (OCU) is highlighted as a central aspect of knee joint preservation. The discussion encompasses the biomechanical considerations and outcomes associated with various cartilage restoration techniques. Factors influencing procedure selection, including lesion size, location, and patient-specific variables, are thoroughly examined. Additionally, the review underscores the critical role of post-operative rehabilitation and conditioning programs in optimizing outcomes. Strengthening the surrounding musculature, enhancing joint stability, and refining movement patterns are paramount in facilitating the successful integration of preservation procedures. This narrative review aims to provide a comprehensive resource for surgeons, engineers, and sports medicine practitioners engaged in the care of tactical athletes and the field of cartilage restoration. The integration of advanced preservation techniques and tailored rehabilitation protocols offers a promising avenue for sustaining knee joint health and function in this demanding population.

Bipolar Lesions of the Knee Are Associated With Inferior Clinical Outcome Following Articular Cartilage Regeneration. A Propensity Score-Matched Analysis Including 238 Patients of the German Cartilage Registry (KnorpelRegister DGOU)

PURPOSE

To determine whether bipolar lesions (BL) are associated with inferior clinical outcome following articular cartilage regeneration (CR) compared to unipolar lesions (UL).

METHODS

A registry-based study, including patients undergoing isolated CR for focal knee cartilage lesions was performed. Lesions were considered UL or BL depending on the opposing cartilage. Propensity score matching was applied to eliminate potential confounders. Two groups comprising 119 patients with similar baseline characteristics were matched. The Knee Injury and Osteoarthritis Outcome Score (KOOS) at baseline, 6, 12, 24, and 36 months following CR served as primary outcome measure. KOOS improvement, reaching the minimal clinically important difference (MCID), KOOS subcomponents, and failure rates were calculated.

RESULTS

Autologous chondrocyte implantation (ACI) was the most frequently performed procedure in both groups with 63.0% (BL) and 46.6% (UL). There was a significant difference regarding KOOS at 24 months between UL (76.39 ± 14.96) and BL (69.83 ± 18.83; P = .028), which did not exceed the threshold of MCID. No significant difference was detected at any other follow-up. KOOS improvement from baseline was lower in the BL group at all follow-ups and peaked at 36 months in both groups (UL [26.00 ± 16.12] vs. BL [16.63 ± 17.29]; P = .024). The failure rate in the BL group was higher at 8.2% (9/110) compared to the UL group at 3.9% (4/98) (P = .256).

CONCLUSIONS

BL were associated with worse clinical outcome 2 years following CR compared to UL. However, both groups showed an ongoing clinical improvement up to 3 years postoperatively and a low failure rate. While inferior clinical improvement and a lower clinical response rate may be expected in BL patients, the observed differences do not justify excluding these patients from CR.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic trial.

Treatment of Cartilage Defects of the Knee in Military Tactical Athletes: An Overview of Management and Clinical Outcomes

Cartilage defects of the knee are a common problem that can be caused by trauma or chronic repetitive overload and result in debilitating functional limitations. These consequences are of particular significance to military service members, who, by in large, are a group of young, active individuals with professional duties requiring full, unrestricted activity and function. The burden of knee chondral-related disease among military tactical athletes is well established, and systematic approach to the evaluation of a military member with suspected knee chondral pathology facilitates the execution of a surgical procedure that maximizes the likelihood of a return to duty. Despite advances in cartilage restoration surgery, chondral pathology of the knee remains a vexing problem and an omnipresent threat to military medical readiness and warfighter lethality.