MPFL Reconstruction Combined with a Modified Elmslie-Trillat Procedure for Recurrent Patellofemoral Instability.

Several combined procedures have been reported for treating recurrent patellofemoral instability (RPI) with various types and severity of morphological abnormalities, but none have identified absolute threshold values as indications for surgery. We performed medial patellofemoral ligament (MPFL) reconstruction combined with a modified Elmslie-Trillat (ET) procedure on 24 knees (10 male and 11 female patients) to treat RPI with morphological abnormalities corresponding to elevated tibial tubercle-trochlear groove (TT-TG) distance, significant patella alta, and trochlear dysplasia. The inclusion criteria were RPI with morphological abnormalities corresponding to one or more of the following: sulcus angle > 160 degrees, trochlear dysplasia of Dejour classification C or D, Caton-Deschamps index > 1.5, lateral shift ratio > 50%, congruence angle > 15 degrees, or TT-TG distance > 20 mm, including habitual dislocation of the patella. Skeletally immature patients and those with congenital dislocation of the patella were excluded. The Kujala score, International Knee Documentation Committee subjective score, Knee Injury and Osteoarthritis Outcome score (KOOS), and each item of the KOOS improved significantly after surgery. Patellar apprehension sign was present preoperatively in all cases, but all disappeared postoperatively. No instance of postoperative redislocation was observed. On radiographic examination, the mean Q angle, tilting angle, lateral shift ratio, congruence angle, Caton-Deschamps index, Insall-Salvati index, and TT-TG distance improved significantly after surgery. There were no significant differences in sulcus angle after surgery. These results suggest MPFL reconstruction combined with a modified ET procedure provides satisfactory outcomes based on radiological and clinical evaluations for RPI with morphological abnormalities corresponding to elevated TT-TG distance, significant patella alta, and trochlear dysplasia.

Polydactyly-derived allogeneic chondrocyte cell-sheet transplantation with high tibial osteotomy as regenerative therapy for knee osteoarthritis.

Allogeneic cell therapies are not fully effective in treating osteoarthritis of the knee (OAK). We recently reported that transplantation of autologous chondrocyte cell-sheets along with open-wedge high tibial osteotomy promoted hyaline cartilage repair in humans. Here we describe our regenerative therapy for OAK using polydactyly-derived allogeneic chondrocyte cell-sheets (PD sheets) and temperature-responsive culture inserts. Ten patients with OAK and cartilage defects categorized arthroscopically as Outerbridge grade III or IV received the therapy. Cartilage viscoelasticity and thickness were assessed before and after transplantation. Arthroscopic biopsies obtained 12 months after transplantation were analyzed histologically. Gene expression was analyzed to evaluate the PD sheets. In this small initial longitudinal series, PD sheet transplantation was effective in treating OAK, as indicated by changes in cartilage properties. Gene marker sets in PD sheets may predict outcomes after therapy and provide markers for the selection of donor cells. This combined surgery may be an ideal regenerative therapy with disease-modifying effects in OAK patients.

Analysis of the running position of the popliteal artery and branching level of the anterior tibial artery detected by magnetic resonance imaging to avoid vessel injury during surgery around the knee joint.

Background: Vessel injuries during total knee arthroplasty or high tibial osteotomy are rare but have serious complications. This study aimed to analyze the running position of the popliteal artery (PA) and branching level of the anterior tibial artery (ATA), using magnetic resonance imaging (MRI). This analysis might be helpful in avoiding unnecessary vessel injury. Methods: In total, 105 patients (41 men and 64 women), whose running position of the PA and branching level of the ATA could be detected by preoperative MRI, were included in this study. We configured zones A, B, C, and D to be 5-10, 15-20, 25-30 and 35-40 mm distal from the lateral tibial plateau in the axial view, respectively. First, the distance between the posterior cortex of the tibia and anterior border of the PA was measured. Second, the PA position from the medial border of the tibia was measured. This measured value was divided by the transverse diameter of the tibia, and multiplied by 100 to obtain the PA position from the medial border of the tibia. Third, the branching level of ATA was measured from the joint line. Subsequently, each value was compared between men (the M group) and women (the W group). Results: The distance between the posterior cortex of the tibia and the anterior border of the PA was 5.5 ± 1.9, 10.4 ± 2.4, 12.5 ± 2.3 and 12.5 ± 2.3 (mm; mean ± SD) in zones A, B, C, and D, respectively. Comparing both groups, this distance was significantly larger (more separated posteriorly) in zones C and D in the M group. The PA position from the medial border of the tibia was 51.7 ± 6.5, 52.7 ± 8.2, 56.7 ± 10.5 and 66.8 ± 14 (%; mean ± SD) in zones A, B, C, and D, respectively. On comparing the two groups, this position was significantly larger (more laterally shifted) in zone D in the W group. The branching level of the ATA was not detected within 40 mm distal to the joint line in 92 patients (87.6%). However, it was detected within 40 mm (mean 32.5 mm; range 20-38) in 12 patients (11.4%). Among them, 11 were women. Only one woman had an aberrant branching pattern: the ATA bifurcated at the joint level. Conclusion: The PA positioned closest at the joint level, gradually separated and shifted laterally towards the distal side. The distance between the posterior cortex of the tibia and the anterior border of the PA was closer in women than in men in zones C and D. Although a difference of 2 mm is small, the risk of PA injury can be considered to be higher in women than in men. Furthermore, ATA injury is also a concern during retraction of the tibialis anterior muscle posteriorly, and the descending cut of the tibial tuberosity, particularly in women.

Total Knee Arthroplasty Is Superior to Open Wedge High Tibial Osteotomy in Terms of Pain Relief for Patients With Osteoarthritis.

BACKGROUND: Globally, total knee arthroplasty (TKA) is widely performed on patients with osteoarthritis. Meanwhile, open wedge high tibial osteotomy (OWHTO) has garnered attention in our country as a joint-preserving procedure. This study aimed to retrospectively compare the postoperative clinical outcomes of TKA and OWHTO for patients with osteoarthritis. METHODS: We selected 94 patients (106 knees) who underwent OWHTO or TKA between 2013 and 2018, had complete clinical data, and were followed up for >2 years. Patients were classified into 2 groups depending on the procedure (TKA: n = 49; OWHTO: n = 45). Patients in the A (= arthroplasty) group were significantly older, with a worse range of motion (ROM) than those in the O (osteotomy) group. There were no significant differences regarding sex and body mass index between groups. Operative time, perioperative blood loss, knee ROM, and Japanese Knee Injury and Osteoarthritis Outcome Score (J-KOOS) were compared between the groups. RESULTS: Significant differences were found between the A and O groups regarding operative time (120 ± 27.2 vs 80.3 ± 23.3 minutes), perioperative blood loss (505.4 ± 271.8 vs 322.6 ± 196.1 mL), knee ROM (flexion; 123.4 ± 16.3° vs 133.7 ± 12.8°), and J-KOOS for pain (87.4 ± 12.5 vs 78.1 ± 15.2 points) and symptoms (86.6 ± 12.3 vs 79.1 ± 13.3 points). There were no significant differences regarding other J-KOOS subscales. CONCLUSIONS: OWHTO involved shorter operative times and less blood loss. However, the O group reported less pain relief. The A group represents an older, likely less active patient population. Therefore, OWHTO is a possible joint-preserving treatment options in younger active patients who may not be interested in arthroplasty.

Clinical Features and Outcomes of Bilateral Atypical Femoral Fractures.

Bilateral atypical femoral fractures (AFFs) are relatively rare. In this report, we retrospectively researched clinical features and outcomes of bilateral AFFs treated at our institution. We previously treated 4 patients (8 limbs) with intramedullary nailing for complete AFFs (6 limbs) and incomplete AFFs (2 limbs). The mean age at the first operation was 53.3 years, and all patients were female. Of the 4 patients, two had breast cancer, and another two had systemic lupus erythematosus. Three of them received bisphosphonates, and 2 received denosumab, proton pump inhibitor, or glucocorticoid therapy. Only 2 of 6 cases of incomplete AFFs had prodromal pain before progressing to complete fracture. The mean interval from the first surgery to contralateral fracture or prophylactic surgery was 16 months. Radiographically, complete bone union was achieved in 6 limbs. However, a small gap at the lateral cortex of fracture site remained in 2 limbs. Finally, all of the patients were pain-free and able to walk without a cane. It is absolutely necessary to confirm contralateral femoral conditions; however, prediction of progression to complete fracture based solely on prodromal pain was difficult. Therefore, we should advise patients about the danger of progression to complete AFFs even if they are asymptomatic, and a prophylactic surgery should be performed after obtaining informed consent.

Retrospective analysis of risk factors for deep infection in lower limb Gustilo-Anderson type III fractures.

BACKGROUND: Open fractures are among the most severe injuries observed in orthopedic patients. Treating open fractures is difficult because such patients with infections may require multiple operations and amputations. Furthermore, only a few studies have focused on antibiotic prophylaxis in open fractures and evaluated how to cover lost soft tissue to increase the success rate of reconstruction. We evaluated the risk factors for deep infection in lower limb Gustilo-Anderson (G-A) type III fractures. MATERIALS AND METHODS: This retrospective study investigated patients who underwent surgical procedures for lower limb G-A type III fractures between January 2007 and January 2017 at our institution. We enrolled 110 patients with 114 lower limb G-A type III fractures (77 G-A type IIIA fractures and 37 G-A type IIIB fractures) who were followed up for at least 2 years. We compared patients presenting infections with those without infections by assessing the following factors: severe contamination, diabetes, smoking, Injury Severity Scale, segmental fracture, location of fracture, G-A classification, damage control surgery, methods of surgery, timing of fixation, combination of antibiotics used, duration of antibiotic prophylaxis, timing of wound closure, and soft-tissue reconstruction failure. RESULTS: Eighteen fractures presented deep infections. Compared with patients without infections, patients developing infections differed significantly in terms of severe contamination (P < 0.01), G-A classification (P < 0.01), duration of antibiotic prophylaxis (P < 0.01), timing of wound closure (P < 0.01), and incidence of soft-tissue reconstruction failure (P < 0.01). Skin grafting was associated with significantly higher failure rates than muscle and free flap reconstructions (P = 0.04). Treatment with antibiotics was significantly longer in patients with drug-resistant bacterial infections than in those without infections (P < 0.01). CONCLUSION: Early flaps rather than skin grafting should be used to cover G-A type IIIB fractures, because skin grafting resulted in the highest failure rate among soft-tissue reconstructions in open fractures. Longer duration of antibiotic use had a significant impact not only on deep infection rates but also on the presence of drug-resistant bacteria. These findings suggest that prolonged use of antibiotics should be avoided in cases of open fractures. LEVEL OF EVIDENCE: Level IV retrospective observational study.

Clinical outcomes of intramedullary nailing of femoral shaft fractures with third fragments: a retrospective analysis of risk factors for delayed union.

BACKGROUND: This study retrospectively evaluated the clinical outcomes of intramedullary nailing of femoral shaft fractures with third fragments and analyzed the risk factors for delayed union. METHODS: Retrospective analyses involving 51 patients who underwent intramedullary nailing of femoral shaft fractures with third fragments (AO classification type B, 35 cases; type C, 16 cases) were conducted. Delayed union was defined as either more than 10 months required for callus formation in more than three of the four cortical bone surfaces observed in the frontal and lateral radiographic views or the requirement for additional surgery such as nail conversion or bone transplantation. Seventeen patients developed delayed union (D group). Thirty-four patients achieved bony union within 9 months (U group). The following background variables were compared between groups: age at the time of the injury; AO classification; ratio of open fracture; waiting period before surgery; rate of the infraisthmal fracture; diameter of the intramedullary nail; ratio of the intramedullary nail to the femur; length and displacement of the third fragment; and use of open reduction, poller screws, or dynamization. RESULTS: Significant differences were found between the D and U groups for age (32.2±14.1 vs. 25.3±9.6 years), open fracture ratio (35.3% vs. 11.8%), and displacement of the third fragment (13.7±6.4 vs. 9±6.3 mm). Multiple logistic regression analysis only identified displacement of the third fragment as a risk factor for delayed union (p=0.03; OR 1.13; 95% CI 1.01 to 1.26). DISCUSSION: Delayed union was observed in 17 cases (33.3%) after intramedullary nailing of femoral shaft fractures with third fragments. Displacement of the third fragment influenced delayed union. LEVEL OF EVIDENCE: Level III.

Combined surgery and chondrocyte cell-sheet transplantation improves clinical and structural outcomes in knee osteoarthritis.

Current cartilage regenerative therapies are not fully effective in treating osteoarthritis of the knee (OAK). We have developed chondrocyte sheets for autologous transplantation and tested these in in vitro and in vivo preclinical studies, and have reported that the transplantation of chondrocyte sheets promoted hyaline cartilage repair in rat, rabbit, and minipig models. However, autologous transplantation of chondrocyte sheets has yet to be reported in humans. Here, we report our combination therapy in which conventional surgical treatment for OAK, is followed by autologous chondrocyte sheet transplantation for cartilage repair. Eight patients with OAK and cartilage defects categorized arthroscopically as Outerbridge grade III or IV receive the therapy. Patients are thoroughly assessed by preoperative and postoperative X-rays, magnetic resonance imaging (MRI), arthroscopy, Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm Knee Score (LKS), and a laser-induced photoacoustic method to assess cartilage viscoelasticity. Arthroscopic biopsies of all patients are performed 12 months after transplantation for histological evaluation. The properties of the chondrocyte sheets are evaluated using gene expression analysis to investigate the ability to predict the clinical and structural outcomes of the therapy. For this small initial longitudinal series, combination therapy is effective, as assessed by MRI, arthroscopy, viscoelasticity, histology, and the clinical outcomes of KOOS and LKS. Gene marker sets identified in autologous chondrocyte sheets may be predictive of the overall KOOS, LKS, and histological scores after therapy. These predictive gene sets may be potential alternative markers for evaluating OAK treatment.

Multilineage-differentiating stress-enduring (Muse)-like cells exist in synovial tissue.

INTRODUCTION: Cartilage regeneration is a promising therapy for restoring joint function in patients with cartilage defects. The limited availability of autologous chondrocytes or chondrogenic progenitor cells is an obstacle to its clinical application. We investigated the existence and chondrogenic potential of synovial membrane-derived multilineage-differentiating stress-enduring (Muse)-like cells as an alternative cell source for cartilage regeneration. METHODS: Cells positive for stage-specific embryonic antigen-3 (SSEA-3), a marker of Muse cells, were isolated from the synovial membranes of 6 of 8 patients (median age, 53.5 years; range 36-72 years) by fluorescence-activated cell sorting. SSEA-3-positive cells were cultured in methylcellulose to examine their ability to form Muse clusters that are similar to the embryoid bodies formed by human embryonic stem cells. Muse clusters were expanded and chondrogenic potential of M-cluster-derived MSCs examined using a pellet culture system. Chondrogenic differentiation was evaluated by proteoglycan, safranin O, toluidine blue and type II collagen staining. To evaluate the practicality of the procedure for isolating Muse-like cells, we compared chondrogenic potential of M-cluster derived MSCs with expanded cells derived from the clusters formed by unsorted synovial cells. RESULTS: Synovial membranes contained SSEA-3-positive cells that after isolation exhibited Muse-like characteristics such as forming clusters that expressed NANOG, OCT3/4, and SOX2. In the pellet culture system, cell pellets created from the M-cluster-derived MSCs exhibited an increase in wet weight, which implied an increase in extracellular matrix production, displayed metachromasia with toluidine blue and safranin O staining and were aggrecan-positive and type II collagen-positive by immunostaining. Unsorted synovial cells also formed clusters in methylcellulose culture, and the expanded cell population derived from them exhibited chondrogenic potential. The histological and immunohistochemical appearance of chondrogenic pellet created from unsorted synovial cell-derived cells were comparable with that from M-cluster-derived MSCs. CONCLUSIONS: Muse-like cells can be isolated from the human synovial membrane, even from older patients, and therefore may provide a source of multipotent cells for regenerative medicine. In addition, the cluster-forming cell population within synovial cells also has excellent chondrogenic potential. These cells may provide a more practical option for cartilage regeneration.

Delayed methicillin-resistant Staphylococcus aureus-induced osteomyelitis of the tibia after pin tract infection: two case reports.

BACKGROUND: Pin tract infection is a common complication of external fixation. It usually heals after treatment with debridement, antibiotics, and/or pin removal, only rarely developing into delayed osteomyelitis. We treated two patients with delayed methicillin-resistant Staphylococcus aureus-induced osteomyelitis of the tibia following pin tract infection. CASE PRESENTATION: One patient, a diabetic 60-year-old Japanese man, underwent definitive external fixation using an Ilizarov fixator for postoperative osteomyelitis of an open fracture of his left ankle. One year after removing the external fixator, he developed methicillin-resistant Staphylococcus aureus-induced osteomyelitis of the tibial pin site. He underwent surgical debridement four times. No recurrence was seen 2 years 8 months after the last debridement. Another patient, a healthy 38-year-old Japanese man, underwent bilateral temporary external fixation for a right ankle open fracture and a comminuted fracture of the left tibial plateau. Three months after removal of the external fixator, he was diagnosed with methicillin-resistant Staphylococcus aureus-induced osteomyelitis of the bilateral tibial pin sites. He underwent surgical debridement three times, but the infection of his right tibia persisted. Finally, a gastrocnemius muscle flap was placed. No recurrence was seen 2 years after this last surgery. CONCLUSIONS: Pin tract infection should not be considered a minor complication because osteomyelitis may develop, requiring treatment that is more aggressive than curettage of the pin tract. A gastrocnemius flap is a useful treatment option for refractory osteomyelitis because flap harvest causes less functional disturbance and is a relatively easy surgical technique.

Modified Elmslie-Trillat Procedure for Recurrent Dislocation of the Patella.

Many groups have reported good to excellent clinical outcomes of the Elmslie-Trillat (ET) procedure for recurrent dislocation of the patella. However, the mean follow-up period of these studies was no more than 5 years. We hypothesized that the long-term postoperative outcomes of the modified ET procedure for recurrent dislocation of the patella would be acceptable compared with those of other procedures. The long-term postoperative outcomes of patients treated with the modified ET procedure were examined. A total of 31 knees in 27 patients with recurrent dislocation of the patella who underwent a modified ET procedure (without medial capsular plication) were evaluated. The mean follow-up period was 13.0 years. Pre- and postoperative radiographs were examined to determine the Q-angle, tilting angle, lateral shift ratio, sulcus angle, congruence angle, and Insall-Salvati index. Clinical outcomes were evaluated based on the Fulkerson patellofemoral joint evaluation score, Kujala score, and the presence of the apprehension sign. Radiological evaluation revealed significant postoperative improvements in the Q-angle, tilting angle, lateral shift ratio, congruence angle, Kujala score, and Fulkerson score (p < 0.001). Sixty-eight percent of all patients had a "good" or "excellent" Fulkerson score. The apprehension sign continued to be shown for six knees. Progression of osteoarthritic changes was observed in three knees, and one knee was symptomatic. The modified ET procedure provided satisfactory outcomes based on radiological and clinical evaluations. These results show the long-term effectiveness and safety of the modified ET procedure for recurrent patellar dislocation.

Clinical Outcomes of Patients with Valgus Deformity Undergoing Minimally Invasive Total Knee Arthroplasty Through the Medial Approach.

OBJECTIVE: The purpose of this study was to compare the clinical outcomes between patients with a valgus or varus deformity undergoing minimally invasive total knee arthroplasty through the medial approach. METHODS: The patients were classified into 2 groups according to the preoperative femorotibial angle measured on an anteroposterior long leg roentgenogram. The valgus group comprised of 26 knees in 21 patients with a femorotibial angle <170° (163.5 ± 5.7), and the varus group comprised of 24 knees in 21 patients with a femorotibial angle >190° (195.9 ± 5.5). The following background variables were compared between the groups: age at the time of the operation, sex, causative disease, preoperative femoral mechanical-anatomical angle, and postoperative knee range of motion, Knee Society score, femorotibial angle, and implant position. RESULTS: There were significant differences between the valgus and varus groups in the age (68.0 ± 6.9 vs 75.8 ± 6.2 years), percentage of males (23.8% vs 0%), percentage with rheumatoid arthritis (61.9% vs 4.8%), and preoperative femoral mechanical-anatomical angle (6.2 ± 1.0° vs 7.4 ± 2.1°). Clinical outcome variables of postoperative femorotibial angle (173.1 ± 3.9° vs 175.2 ± 1.6°) and α angle (96.6 ± 3.1° vs 95.0 ± 1.9°) also differed. CONCLUSION: It was assumed that over-valgus resection of the femur is a contributory factor to residual valgus alignment. However, knee range of motion and Knee Society score did not differ between the groups. We suggest that minimally invasive total knee arthroplasty through the medial approach is one of the treatment options for patients with valgus deformity.

Retrospective comparison of postoperative infection and bone union between late and immediate intramedullary nailing of Gustilo grades I, II, and IIIA open tibial shaft fractures.

BACKGROUND: The optimal method of skeletal stabilization is still controversial. Therefore, we examined the clinical outcomes associated with late (L) versus immediate intramedullary nailing (IMN). METHODS: This was a retrospective comparative study of trauma registry data from an emergency medical care center (university hospital). We examined 85 open tibial shaft fractures (85 patients) treated with L or immediate (I) IMN from January 2004 to December 2010. The L and I groups comprised 37 (33 men, 4 women) and 48 (44 men, 4 women) patients, respectively. The postoperative infection rate, time to bone union, and delayed union/non-union were evaluated. RESULTS: The mean ages at the time of trauma in the L and I groups were 41.8 (18-79) and 42.0 (18-71) years, respectively; the mean follow-up periods were 15.0 (6-39) and 18.3 (8-36) months, respectively. A higher rate of postoperative infection was found in the L group than in the I group (p=0.004). Superficial/deep infection developed at a higher rate in the L group than in the I group (p=0.042 and 0.045, respectively). Among patients with Gustilo grade IIIA fractures, postoperative infection occurred at a higher rate in the L group than in the I group (p=0.008). However, the delayed union rate, non-union rate, and time to bone union were not significantly different between the groups. CONCLUSIONS: Gustilo grade IIIA fractures had a high infection rate, which is likely due to various factors, including pin-site infection after external fixation. We think that I IMN is safer than L IMN, and it should be the treatment of choice. LEVEL OF EVIDENCE: Retrospective comparative study, level III.

Associations between venous thromboembolism onset, D-dimer, and soluble fibrin monomer complex after total knee arthroplasty.

BACKGROUND: Prevention and early detection of venous thromboembolism (VTE) is important after arthroplasty of the lower limb. The purpose of this study was to investigate the associations between VTE and hemostatic markers after minimally invasive total knee arthroplasty (MIS-TKA). METHODS: We performed a retrospective study of 50 patients (55 knees) who underwent primary unilateral MIS-TKA with periodic determination of D-dimer and soluble fibrin monomer complex (SFMC) concentrations and with ultrasonography. The development of symptomatic and asymptomatic VTE, location of deep venous thrombosis (DVT; proximal or distal), changes in SFMC and D-dimer concentrations, and correlations between hemostatic markers and VTE onset were evaluated. RESULTS: Twenty-six patients (47%) had an asymptomatic distal DVT, but none had proximal DVT, pulmonary embolism, or symptomatic DVT. DVT was detected at postoperative day 1 (POD1) in 16 patients, POD3 in six, and POD5 in three (excluding detections of the same DVT in the same position on different days). DVT onset correlated significantly with SFMC concentration on POD1 and with D-dimer concentration on POD3. The D-dimer concentration did not differ significantly between patients who developed DVT (DVT+) and those who did not (DVT-) at each postoperative time. SFMC concentration differed between DVT+ and DVT- patients only on POD1. Analysis of each hemostatic marker classified as either within or outside the normal concentration range showed no significant correlations between D-dimer concentration and DVT onset at each period. There were significant correlations between SFMC concentrations and DVT onset on POD1 and POD3. There were also significant correlations between D-dimer positive (+) findings and/or SFMC+ findings and DVT onset on POD1 and POD3. D-dimer+ and/or SFMC+ findings had better specificity on POD1 and a positive predictive value on POD1 and POD3 compared with SFMC+ alone. CONCLUSIONS: SFMC concentration is an effective hemostatic marker for early detection of DVT. D-dimer concentration alone has limited value as a hemostatic marker for early detection of DVT. Measurement of both D-dimer and SFMC concentrations might be a more sensitive diagnostic tool than measuring SFMC concentration alone.

Tibia rotational technique to drill femoral bone tunnel in anatomic double-bundle anterior cruciate ligament reconstruction.

In anatomic anterior cruciate ligament (ACL) reconstruction, several pitfalls in creating the femoral bone tunnels at the correct position are of great concern. Our new method, the tibia rotational (TR) technique, may contribute to resolving these. The purpose of this study is to describe further details about the TR technique in anatomic double-bundle ACL reconstruction. Both anteromedial and posterolateral femoral bone tunnels were drilled through a posterolateral tibial bone tunnel using tibial rotation without deep knee flexion. When it is difficult to reach the mark with the rigid guide pin, the narrow curved TR technique guide and the flexible drill system allow drilling femoral bone tunnels in the correct position. The TR technique offers the technical ease required for widespread acceptance while prioritizing the fundamental goals of an anatomic double-bundle ACL reconstruction.

Articular cartilage regeneration using cell sheet technology.

Cartilage damage is typically treated by chondrocyte transplantation, mosaicplasty, or microfracture. Recent advances in tissue engineering have prompted research on techniques to repair articular cartilage damage using a variety of transplanted cells. We studied the repair and regeneration of cartilage damage using layered chondrocyte sheets prepared in a temperature-responsive culture dish. We previously reported achieving robust tissue repair when covering only the surface layer of partial-thickness defects with layered chondrocyte sheets in domestic rabbits. We also reported good Safranin O staining and integration with surrounding tissue in a minipig model of full-thickness cartilaginous defects in the knee joint. We have continued our studies using human chondrocytes obtained from patients under IRB approval, and have confirmed the safety and efficacy of chondrocyte sheets, and have submitted a report to the Ministry of Health, Labour, and Welfare in Japan. In 2011, the Ministry gave us approval to perform a clinical study of joint repair using cell sheets. We have just started implanting cell sheets in patients at Tokai University Hospital.