Experimental Study On The New Low Elastic Modulus β Tialloy Mini- Prothesis Resurface The Articular Surface Defect

BackgroundBy the trauma, tumor, osteochondritis dissecans and degenerative joint and other articular cartilage due to partial necrosis of full thickness defects and degeneration are more common. Data indicate that the articular cartilage without blood vessels, nerves and lymph supply, while the environment in which the cartilage cells and relatively isolated, which makes the healing of cartilage is weak, so how to repair cartilage defects caused by bone and joint diseases become the issues of common concern to medical workers. Existing treatments all have drawbacks: Conservative therapy at best ameliorates the symptoms and debridement, abrasion chondroplasty, subchondral drilling, and microfracturing result in only fibrous or fibrocartilage tissue formation. All of the aforementioned treatments are increasingly ineffective in older patients. The use of biomaterials, periosteal or perichondral grafts, and cytokine or gene therapies prompts encouraging experimental data but unpredictable clinical results. Unicompartmental or total knee arthroplasties therefore represent procedures of final resort for some middle-aged patients, prompting the likelihood of revision surgery and associated morbidity during the patient's lifetime. ObjectiveThrough this experiment, to assess the effect and the feasibility of the new low elastic modulusβTi alloy mini-prothesis resurfacing the articular surface in dogs. The objective of this study was to provide a temporary or alternative treatment strategies for the middle-aged patient (40–50 years old)with a focal ICRS grade IV lesions to delay joint replacement, maintenance of joint function in patients with more time for clinical application to provide more reliable experimental basis.MethodsA full-thickness osteochondral defect of 7 mm in diameter was created at the medial femoral condyle of both hind limbs in 16 healthy adult dogs. The titanium alloy mini-prostheses with high-modulus of elasticity were implanted on the right side (control group) and those with low-modulus of elasticity on the left side (experiment group) to repair the cartilage defects. After 3 months, all the 16 dogs were sacrificed to harvest the specimens. Radiographic, histologic,micro-CT and biomechanics examinations were conducted to observe stability of the mini-prostheses and growth of the bone and cartilage surrounding the implants.ResultsRadiographic evaluation revealed no indications of device disassembly or subsidence. Cartilage around the cap grew well and the surface remained smooth. Periphery of the resurfacing implant was covered by an extension of the superficial cartilage emanating from the defect margins. Micro-CT data revealed that the bone volume fraction, trabecular thickness, trabecular number and tissue mineral density were 0.389±0.025%, 0.049±0.002μm, 8.9±0.4 mm^-1 and 652.7±12.6 mg/mm³ respectively in the experiment group, compare with 0.253±0.024%, 0.038±0.002μm, 5.9±0.4 mm^-1 and 595.2±7.6 mg/mm³ in the control group, with statistically significant differences between the 2 groups (P<0.05). Bone trabeculae surrounding anchoring screws in the experiment group was visibly more and denser compared with the control group. The maximal axial pullout strength was 181.3±2.17 N in experiment group ,which were significantly higher than those of 143.8±1.38 N in control group(P<0.05).ConclusionThe new low elastic modulusβTi alloy mini-prothesis is favourable toward resurfacing the articular surface defect. The low-modulus of elasticity can enhance the biological stability of the prosthesis.