Search

Case A 49-year-old woman injured her anterior cruciate ligament (ACL) as a high-school student. Double-bundle ACL reconstruction (DBACLR) using hamstring tendon grafts was performed because of recurrent instability. Eleven years after DBACLR, total knee arthroplasty was performed because of osteoarthritis progression. Histologic analysis was completed to observe the osteointegration of the tendon in the obtained proximal tibia. The tibial tunnel showed Sharpey-like fibers anteriorly, connecting the tendon graft and lamellar bone, whereas the intraarticular exit revealed well-aligned chondrocytes posteriorly, indicating chondral metaplasia of the tendon graft. Conclusion Tendon-bone healing can regenerate both fibrous insertion and chondral metaplasia in DBACLR.

The purpose of this study was to investigate the incidence of cyclops lesions and its relationship with the cross-sectional area of the intercondylar notch.For this study, 55 patients (24 male and 31 female) underwent follow-up arthroscopy after bi-socket anterior cruciate ligament reconstruction with hamstring tendon grafts were included. All patients underwent magnetic resonance imaging measurements of intercondylar notch dimensions. We compared the femoral intercondylar notch sizes and bone tunnel sizes between knees with cyclops lesions (cyclops group) and those without cyclops lesions (no-cyclops group). The mean percentage of the tunnel size to the cross-sectional area of the femoral intercondylar notch was also compared between the groups. The median follow-up duration was 3.8 years.Cyclops lesions were found in 15 of the 55 knees (27.3 %) on second-look arthroscopy (cyclops group). Only 6 of the 55 knees (10.9 %) had extension loss (cyclops syndrome). The cyclops group included 3 men and 12 women. The two groups showed a statistical difference in sex variation (P = 0.04). No significant differences were found in the femoral and tibial tunnel sizes between the two groups. The cross-sectional area of the femoral intercondylar notch was significantly smaller in the cyclops group (251.7 ± 63.2 mm(2)) than in the no-cyclops group (335.6 ± 77.6 mm(2)) (P 0.001). The percentage of the total femoral tunnel size to the cross-sectional area of the femoral intercondylar notch was significantly higher in the cyclops group (18.6 ± 5.3 %) than in the no-cyclops group (13.2 ± 3.6 %) (P = 0.02).A smaller intercondylar notch size may be a potential risk factor for cyclops lesion formation.Case-control study, Level IV.

Toolpath generation for a multi-axis medical machine tool is a challenging task. In surgical procedures, it is difficult to apply industrial CAM technology owing to the requirement for quick toolpath generation and the likelihood of tool interference with complex structures of the target area. The objectives of this study are to optimize the initial position and posture of the cutting tool for performing the ideal skin incision and to minimize contact between the cutting tool and the surrounding area. We propose a novel toolpath strategy based on geometric models. It can be potentially applied to general machine-assisted surgeries.

Optimal control of the machining process in orthopedic surgery can not only increase productivity but also ensure safety during tool usage. The authors have developed a technology for a force control system. The system has two modes of operation: the “air-cutting mode” and the “force control mode.” In the air-cutting mode, tool feed is scheduled by predicting the air and bone-cutting zones from the CAD/CAM system. In the force control mode, the software monitors the cutting force and the cutting temperature, and it controls the feed override according to the difference between the real and the desired cutting force. The software is installed on a robot controller, and its effectiveness is evaluated with a urethane bone.

We prospectively evaluated the disease-specific features of the early postoperative plasma D: -dimer value and the relationship with deep venous thrombosis and/or pulmonary thromboembolism (DVT/PE) in 95 patients following total knee arthroplasty. Patients in whom DVT/PE was highly suspected were diagnosed by high-resolution multi-detector row computed tomography scanning (MDCT). Forty-nine knees in 46 patients with rheumatoid arthritis (RA, 24 knees) or osteoarthritis (OA, 25 knees) were finally recruited. DVT/PE was detected in 28 (57.1%) of the 49 cases examined by diagnostic MDCT: 12 (50.0%) of the 24 cases of RA, and 16 (64.0%) of the 25 cases of OA. Of these, PE was found in 11 cases (39.2%), but none of them showed clinical symptomatic signs of dyspnea or chest pain. In both RA and OA cases, there were statistically significant differences in the D: -dimer value on postoperative day 3 (P = 0.027) and after day 28 (P = 0.037) between the groups with and without DVT/PE. In OA cases, there were significant differences between the two groups on postoperative days 1 (P = 0.034), 3 (P = 0.020), 5 (P = 0.005), and 7 (P = 0.045), respectively. At the baseline, perioperative D: -dimer levels in the RA group without DVT/PE were higher than in the OA group. However, multivariate logistic regression analysis showed that RA was not a significant risk factor of DVT/PE in comparison with OA. In conclusion, individual evaluation of the D: -dimer level between RA and OA should provide a more precise predictive indicator of early postoperative DVT/PE.

To differentiate benign from malignant bone tumors by analyzing the vascular distribution within bone tumors with dynamic contrast-enhanced MRI.We studied dynamic contrast-enhanced MRI for 49 bone tumors (22 malignant and 27 benign tumors). Seven small regions of interest (ROI) were set inside the largest portion of each tumor. Four ROI were placed evenly on the periphery and three ROI were placed evenly on the line of the longest breadth within the tumor. The slope of the curve (%Slope) was calculated on the time-intensity curves of the whole tumor and of each ROI. The variance values for the %Slope of the ROI were calculated to assess the dispersion of the intensity change at each ROI within the tumor.Mean value of the %Slopes of whole tumor regions for malignant bone tumors (70.4 +/- 60.3%) was significantly higher than that for benign bone tumors (37.6 +/- 52.9%) (P = 0.015), although giant cell tumor (GCT), a locally aggressive tumor, had a relatively higher %Slope. Mean value of the variance of %Slopes for malignant bone tumors (3485.9 +/- 5942.5) was significantly higher than that for all benign tumors (470.4 +/- 583.9) (P = 0.012), indicating that the %Slope values of seven ROI within malignant bone tumors varied more widely compared with the ROI inside benign bone tumors. GCT also demonstrated a lower value.Our method of analyzing the signal intensity change at seven separate regions that evaluates the vascular distribution within a tumor could be a useful tool for differentiating between benign and malignant bone tumors.

In successful knee arthroplasty, the femur and the tibia must be shaped to fit an artificial joint. The recent trend towards MIS (Minimally Invasive Surgery) to decrease the length of the required incision in the skin has increased surgical difficulty, since the open access area is small. The developed system consists of (1) a preplanning system providing a CAD function, (2) a multi-axis CAM system which avoids cutting the skin and the ligament, and keeps the cutting time within acceptable limits, and (3) a 7-axis machine tool that assures the safety of the patient and the surgeon, and enables MIS.

Bone cutting experiments were conducted on a cadaver using a newly developed machine tool. The effectiveness of the system was evaluated by comparing the planned shape for the mating surface between the femur and an artificial joint with the cutting result. It is desirable to know the machining phenomena and characteristics at the microscale because the material and the tissue structure are anisotropic in both cortical and cancellous bones. In the paper, the influence of the material characteristics on machining is discussed for cortical bone. Pig cortical bone was used in the experiment for visualizing 2-dimensional micro-cutting.

We measured the cross-sectional area (CSA) of the semitendinosus tendon (SMT) in 79 anterior cruciate ligament (ACL)-injured patients using magnetic resonance imaging (MRI) to scrutinize their appropriateness for ACL grafts. Measurements of the CSAs of the SMT with MRI were closely correlated with intraoperative direct measurement (y = 0.697). The mean CSAs of the SMT measured with MRI ranged from 6.3 to 15.0 mm2 with a mean of 10.1+/-2.1 mm2. The CSA of the SMT measured with MRI proved to be a useful indicator to determine preoperatively whether the SMT graft would be of adequate dimensions (7 mm or more in diameter, 60 mm or more in length) for ACL reconstruction. If the CSA of the SMT was more than 11 mm2, a sufficiently thick and long graft could be prepared with a tripled or quadrupled SMT in 89% of cases. We conclude that tissue CSA measurements using MRI could potentially be implemented as a useful tool for determining the most appropriate donor autograft tissue preoperatively, thus minimizing harvest-site morbidity.

Clinical and radiographic studies were performed on 228 hips of 145 patients with avascular necrosis of the femoral head (ANFH). The patients were divided into three groups: group A consisted of 33 patients with systemic lupus erythematosus (SLE) who had been treated with systemic corticosteroids (59 hips); group B consisted of 41 patients with a history of corticosteroid treatment, excluding patients with SLE (69 hips); and group C consisted of 71 patients with no history of corticosteroid use (100 hips). Of the 228 hips, 80 hips at an early stage of the necrosis, but not showing collapse, were selected and classified by the criteria of the Japanese Investigation Committee (JIC) to define the natural history of the disease. In the SLE patients (group A), there was a predisposition to bilateral involvement and multiple sites of bone necrosis. Eighty percent of the femoral heads followed at an early stage had collapsed at the end of the follow-up, the incidence of collapse in group A being higher than that in the other groups. The collapses in group A were predominantly types 1C, 2, and 3B according to the JIC criteria. The incidence of collapse was significantly lower in type 1A and type 3A than in the other types. The classification proposed by the JIC, in terms of types with regard to size and location of the necrotic area on antero-posterior radiographs, was very useful for evaluation of the risk of collapse as well as for selecting appropriate treatment modalities, either conservative or surgical, during the early stages of ANFH.

Loose fragments in spontaneous osteonecrosis of the knee (SONK) are usually removed by surgical treatment. However, the healing potential of osteonecrotic loose fragments and their clinical availability, for example as a cell source for cartilage repair and tissue engineering, have not been investigated. The objective of this study was to evaluate the cellular proliferation and redifferentiation ability of loose fragment chondrocytes for the treatment of SONK.Cells were obtained from the remaining cartilage of chondral loose fragments or fibrocartilaginous tissue under the affected femoral condyle in SONK. The proliferation activity of loose fragment-derived chondrocytes and condyle-derived fibrochondrocytes was evaluated. In-vitro differentiation ability was assessed by PCR and histological analysis.The deposition of proteoglycans and type II collagen were maintained in loose fragments. However, loose fragment-derived chondrocytes had lower proliferating activity than condyle-derived fibrochondrocytes. Chondrogenic redifferentiation ability was lower in loose fragment chondrocytes than in condyle fibrochondrocytes. Differentiation towards adipogenic and osteogenic lineages was not observed in loose fragment chondrocytes. On the other hand, lipid vacuoles were detected in fibrochondrocytes after adipogenic treatment.This study demonstrated that loose fragment-derived chondrocytes in SONK had lower potential than fibrochondrocytes in cellular proliferation and redifferentiation. Our experimental results suggest that osteonecrotic loose fragments might have restricted cellular properties in the healing of SONK-related osteochondral defects.

Many of the robots developed so far, including our multi-axis bone cutting robot, use an end mill as the cutting tool, and some problems should be solved to apply them to the minimally invasive orthopedic surgery. Minimally invasive surgery makes the incisions smaller, reduces pain and trauma to the body, and enables faster recovery. The smaller incision means a small and narrow opening area. This means the robot attitude for the bone resection is restricted, and it can result in the collision of the tool with the surrounding tissue, the existence of an untouched area and the degradation of the joint position accuracy. This paper proposes a robot mechanism and a toolpath generation technique specialized for bone cutting is expected to resolve these issues.

Recent clinical studies have investigated postural sway characteristics in anterior cruciate ligament (ACL)-deficient knees, but the relative contributions of vision and ACL remain unclear. In the current study, we measured and compared postural sway during one-leg standing with eyes open and closed to assess the difference between legs with and without ACL injury, and we discuss the contribution of the ligament relative to vision and to postural sway in patients. We examined 32 patients (17 males, 15 females) with ACL injury before surgery from March 2001 through January 2004. None presented obvious dysfunction in the lower limbs or central nervous system. Using a gravicorder, we measured locus length per time (LG) and environmental area (AR) as the factors of postural sway during two-leg and one-leg standing with eyes open or closed. In the ACL-injured knee, the amount of postural sway increased significantly during injured leg standing with eyes closed (LG, P < 0.0001; AR, P < 0.0001), but it did not increase significantly with eyes open. There were no significant differences with respect to sex or general joint laxity. There was no correlation between postural sway and the anterior translation of the tibia measured by arthrometer KT2000 or between the muscle strength around the knee. We concluded that the amount of postural sway in the ACL-injured knee increased significantly on injured leg standing with eyes closed, and that vision appears to be dominant in compensating for the decreased contribution of the injured ACL.

Ninety-four patients with osteoarthritis (OA) and 180 with rheumatoid arthritis (RA) undergoing unilateral total knee arthroplasty (TKA) were analyzed to clarify the necessity for preoperative autogenous blood deposition or homologous blood transfusion. Two hundred and twenty-four and 50 patients underwent TKA with cement and without cement, respectively. The difference in average blood loss in patients between with (372 ml) and without cementation (449 ml) was significant. In the OA group the average blood loss significantly decreased after cementation but not in the RA group. Although the rate of avoiding transfusion in the OA group did not significantly decrease with the use of cement (92.4% vs. 93.3%), that in the RA group did (80% to 57.1%). Eight of 159 patients with hemoglobin level (Hb) of 11.0 g/dl or higher received homologous blood transfusion. Of these eight patients five had associated disorders. Only one patient with Hb of 12.0 g/dl or higher underwent homologous blood transfusion. Patients with Hb of 12.0 g/dl or higher are not indicated for preoperative autologous blood deposition. In patients with Hb between 11.0 and 12.0 g/dl preoperative blood deposition may be planned after consideration of general condition and complication. Patients with Hb lower than 11.0 g/dl should undergo preoperative blood deposition.