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PURPOSE: This study aimed to compare in vivo kinematics during weight-bearing daily activities and determine the relationship with clinical outcomes in patients undergoing total knee arthroplasty (TKA) with a medial-pivot (MP, Evolution™) versus a posterior-stabilized (PS, Persona®) design under constant conditions of intraoperative soft tissue balance. METHODS: Forty patients undergoing MP or PS-TKA under similar conditions of soft tissue balance were enrolled in this prospective randomized controlled trial. Outcome measures included clinical knee society scores (KSS) and knee injury and osteoarthritis outcome scores (KOOS). A kinematic assessment was conducted while the participants performed lunge and step-up activities under fluoroscopic guidance. RESULTS: Eighteen patients in each arm completed 1-year follow-up and were included in the analysis. All patients experienced pain relief and satisfactory knee function postoperatively. In kinematics, in the MP arm, the medial femoral condyle remained consistent, whereas the lateral femoral condyle gradually shifted posteriorly with increasing knee flexion. Conversely, in the PS arm, paradoxical anterior movement of the medial femoral condyle accompanied the lateral pivot motion. During lunge and step-up activities, a medial-pivot motion was observed in 83% and 72% of knees in the MP arm, respectively, compared with 22% and 11% in the PS arm. Despite these differences in kinematics, there were no statistically significant differences in the KSS and KOOS between the two groups. CONCLUSION: Under weight-bearing conditions during flexion, knees that underwent Evolution™ MP-TKA did not show superior clinical results compared to Persona® PS-TKA, despite exhibiting in vivo kinematics closely resembling the normal in vivo pattern. LEVEL OF EVIDENCE: Therapeutic studies-Level I.

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BACKGROUND: Articular cartilage degeneration can develop after anterior cruciate ligament reconstruction (ACLR). Although radiological studies have identified risk factors for the progression of degenerative cartilage changes in the long term, risk factors in the early postoperative period remain to be documented. HYPOTHESIS: Cartilage lesions that are present at surgery progress to cartilage degeneration in the early phase after ACLR. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: T1ρ is the spin-lattice relaxation in the rotating frame magnetic resonance imaging. Sagittal T1ρ maps of the femorotibial joint were obtained before and 1 year after ACLR in 23 patients with ACL injuries. Four regions of interest (ROIs) were placed on images of the cartilage in the medial and lateral femoral condyle (MFC, LFC) and the medial and lateral tibia plateau (MTP, LTP). Changes in the T1ρ value (milliseconds) of each ROI were recorded, and differences between patients with and without cartilage lesions were evaluated. The relationship between changes in the T1ρ value and meniscal tears was also studied. RESULTS: Arthroscopy at ACLR detected cartilage lesions in 15 MFCs, 7 LFCs, and 2 LTPs. The baseline T1ρ value of the MFC and LFC was significantly higher in patients with cartilage lesions (MFC, 40.7 ms; LFC, 42.2 ms) than in patients without cartilage lesions (MFC, 38.0 ms, P = .025; LFC, 39.4 ms, P = .010). At 1-year follow-up, the T1ρ value of the MFC and LFC was also significantly higher in patients with lesions (MFC, 43.1 ms; LFC, 42.7 ms) than in patients without such lesions (MFC, 39.1 ms, P = .002; LFC, 40.4 ms, P = .023, respectively). In patients with cartilage injury, the T1ρ value of the MFC increased during the year after treatment (P = .002). There was no significant difference in the baseline and follow-up T1ρ value in patients with or without meniscal tears on each side although the T1ρ value of the MFC, MTP, and LFC increased during the first year after surgery regardless of the presence or absence of meniscal injuries. CONCLUSION: Using T1ρ mapping to detect minimal changes, our study demonstrated that cartilage lesions are related to progressive degenerative cartilage changes during the early phase after ACLR.

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PURPOSE: To investigate the congruency of the articular cartilage surface of the knee between the recipient and donor site during autogenous osteochondral grafting using a three-dimensional (3D) laser scanning. METHODS: Six cadaveric knees were included in this study. The 3D profiles of the articular surface were obtained by a 3D laser scanner (FastSCAN(®), Polhemus). We divided each of the donor and recipient sites into 6 areas in each. The 2 central areas of the donor site were excluded from evaluation because of the trochlear groove. In the donor site, the peripheral and the middle one-third of the femoral articular surface in the medial and lateral patellofemoral joint were extracted. In the recipient site, the peripheral and the middle one-third of the articular surface in the medial and lateral femoral condyle were assessed. In each recipient area, vertical intervals (VIs) of grafts of 6, 8, and 10 mm diameter, showing the distance between highest and lowest point of articular surface were calculated from the data obtained and to the donor sites for matching. RESULTS: ϕ6- and ϕ8-mm grafts The VI of the middle area of the donor site did not differ significantly from that of either the peripheral or the middle area of the recipient site. The VI of the peripheral area of the donor site was significantly higher than that of the peripheral area of the recipient site (p < 0.01). ϕ10-mm grafts The VI of the middle area of the donor site was significantly lower than that of the peripheral area of the recipient site. The VI of the peripheral area of the donor site was significantly higher than that of the middle area of the recipient site (p < 0.01). CONCLUSIONS: An osteochondral graft harvested from the peripheral area of the patellofemoral joint might protrude into the middle area in the recipient site, whereas a ϕ10-mm osteochondral graft harvested from the middle area might be depressed from the peripheral area into the recipient site.

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PURPOSE: To determine the relationship between changes in the extracellular matrix (ECM) and T(1ρ) and T(2) values in vivo. The ECM is composed of proteoglycan (PG), collagen, and water. It has been unclear which of the ECM constituents affects T(1ρ) and T(2) mapping in living human cartilage. MATERIALS AND METHODS: Sagittal T(1ρ) and T(2) maps were preoperatively obtained from 20 knee osteoarthritis patients. Osteochondral samples harvested from the resected tibial plateaus during total knee arthroplasty were consistent with the MRIs of the patients' knees. Parameters that included histological grading of cartilage degeneration, glycosaminoglycan (GAG) content (which constitutes PG), presence of collagen anisotropy and water content were evaluated along with T(1ρ) and T(2) values, and statistical analysis was performed using multiple regression analysis. RESULTS: T(1ρ) and T(2) values were significantly correlated with the degree of cartilage degeneration (ß = 0.397 and 0.357, respectively) and the GAG content (ß = -0.340 and -0.244, respectively). CONCLUSION: The present study demonstrated that T(1ρ) and T(2) values reflect the GAG content of the cartilage and can indicate cartilage degeneration in vivo. Use of these parameters can facilitate the noninvasive diagnosis and evaluation of cartilage degeneration.

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OBJECTIVE: To study the effects of aging and cartilage degeneration of the proximal tibiofibular- and femorotibial joint (PTFJ, FTJ) on the cartilage of the PTFJ using T(1)ρ and T(2) mapping. MATERIALS AND METHODS: We performed sagittal T(1)ρ and T(2) mapping of the PTFJ and FTJ on 55 subjects with knee disorders. We placed 3 regions of interest (ROIs) on images of the cartilage in the PTFJ, medial femoral condyle (MFC), and medial tibia plateau (MTP). Correlation analysis was performed for the T(1)ρ and T(2) values of each ROI and the patient age and the osteoarthritic grade of the PTFJ and FTJ. RESULTS: The T(1)ρ and T(2) values of the PTFJ were affected neither by aging nor the osteoarthritic grade of the FTJ. Values of the FTJ normalized to PTFJ values were correlated with the osteoarthritic grade of the FTJ in the MFC (r=0.851 and 0.779, respectively) and the MTP (r=0.635 and 0.762, respectively). There was a significant difference in the T(1)ρ but not the T(2) value of the PTFJ and MFC between normal and mildly osteoarthritic cartilage of each joint. CONCLUSION: We document that the T(1)ρ and T(2) values of PTFJ cartilage were not affected by aging or cartilage degeneration in the FTJ. The T(1)ρ value of the PTFJ may represent a useful internal standard reference for evaluating early degeneration of the FTJ.

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Several studies have reported that diabetes may cause limited joint motion and often combines with hyperlipidemia (HL). This study clarifies that joint contracture can be produced by diabetes, HL, or both. The experimental animal model, a rat with diabetes and HL, was developed by streptozosin injection and addition of 1% cholesterol to the food. One hindlimb each from the diabetes group, the HL group, the combined diabetes/HL group, and the control group was immobilized for 2, 3, or 4 weeks in the Phase I study. Diabetes/HL rats were used 4 weeks after immobilization in a Phase II study. Joint motion, elasticity of the knee joint capsule, and contractile function of the gastrocnemius muscle were measured. Gastrocnemius muscle was observed histologically by H&E and ATPase staining. Limited joint mobility was observed 4 weeks after immobilization only in the diabetes/HL group. The intraarticular pressure from the saline injection was lower, and the contractile function of the gastrocnemius muscle decreased in this group. Atrophy of type II fiber was observed in the gastrocnemius muscle. This restriction of joint mobility may depend on skeletal muscle degeneration around the joint rather than on an intraarticular lesion.

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BACKGROUND: The effect of University of Wisconsin (UW) solution perfusion for extremity preservation is still unknown although it is widely used. The purpose of this study is to examine the effect of UW solution perfusion on skeletal muscle preservation in a rat model. MATERIALS AND METHODS: Rat hindlimbs were amputated and either preserved with UW solution perfusion (UW perfusion group) or given no perfusion (no-perfusion group) for 5 h at 25 degrees C. They were then transplanted to other isogeneic rats. ATP in the muscle and serum creatine phosphokinase were measured after 24 h of reperfusion. The vascular endothelial function of the femoral artery rings was measured before and after 24 h of reperfusion in the presence or absence of indomethacin (cyclooxygenase inhibitor) and L-NMMA (nitric oxide synthase inhibitor). TEA (calcium-activated potassium channel inhibitor) was also used to verify the vasodilator function. Reperfusion blood flow was monitored during the first 2 h of reperfusion. RESULTS: ATP in the UW perfusion group was significantly decreased after 24 h of reperfusion, while that in the no-perfusion group recovered. Reperfusion blood flow in the UW solution perfusion group was significantly lower than that in the no-perfusion group. Acetylcholine-induced relaxation in the UW perfusion group was significantly reduced before and after 24 h of reperfusion compared to that in the no-perfusion group and was mostly diminished by indomethacin and L-NMMA administration. CONCLUSIONS: Skeletal muscle injury is augmented by UW solution perfusion, probably due to deterioration of the vascular endothelial function resulting in blood supply diminution.

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BACKGROUND: The involvement of nitric oxide (NO) in ischemia-reperfusion injury remains controversial and has been reported to be both beneficial and deleterious. The purpose of this study was to examine the contribution of NO and superoxide to skeletal muscle function using an ischemic revascularized hind limb model in rats. PATIENTS AND MATERIALS: Warm ischemia produced by vascular pedicle clamping was sustained for 3 h. The animals were divided into four groups according to the solution administrated: (1) saline, (2) N-methyl-L-arginine acetate (L-NMMA), (3) L-NMMA + N-(N-L-g-glutamyl-S-nitroso-l-cysteinyl)glycine (S-nitrosoglutathione), or (4) superoxide dismutase (SOD). Saline, L-NMMA, or L-NMMA + S-nitrosoglutathione was infused for the first 2 h of reperfusion. The SOD was administered as an intravenous bolus 5 min before the onset of reperfusion. Postischemic blood flow was measured by a Doppler flow meter. Muscle contractile function was determined after 24 h of reperfusion. RESULTS: Postischemic blood flow was significantly decreased by the L-NMMA infusion compared with that in the saline-treated group. No significant difference in postischemic blood flow was noted in the saline-, L-NMMA + S-nitrosoglutathione-, and SOD-treated groups. Contractile function of the gastrocnemius muscle in the L-NMMA-and SOD-treated groups, but not in the L-NMMA + S-nitrosoglutathione group, was significantly better than that in the saline-treated group. CONCLUSION: Limiting postischemic blood flow and SOD infusion are both beneficial in decreasing the ischemia-reperfusion injury of skeletal muscle. S-Nitrosoglutathione infusion following suppression of endogenous NO production does not reduce ischemia-reperfusion injury.

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