Application of tourniquet in amputation for lower limb gangrene / 中国康复理论与实践

ObjectiveTo explore the efficacy and safety of using a tourniquet in amputation for lower limb gangrene. MethodsAll patients underwent amputation for lower limb gangrene from January, 2009 to June, 2023 in Beijing Bo'ai Hospital were reviewed, involving 41 patients with a total of 44 limbs, and they were divided into non-tourniquet group (n = 28) and tourniquet group (n = 16) according to whether a tourniquet was used during surgery. The amputation field clearness, surgical bleeding, incision healing, reoperation rate within 30 days post-operation, intraoperative blood pressure and heart rate, and operation time were compared. ResultsThe amputation field was clearer in the tourniquet group (χ2 = 42.385, P < 0.001), with less bleeding (Z = -2.082, P < 0.05). No tourniquet-related local damages, such as nerve damage and skin injuries, was observed in the limbs using tourniquets. The incidence of grade A of incision healing was not significantly different (χ2 = 0.028, P = 0.624). ConclusionApplication of tourniquet can improve the amputation field clearness and reduce bleeding during amputation for lower limb gangrene, without affecting incision healing.

Factors related to re-falling of knee range of motion after arthrolysis for post-traumatic knee stiffness / 中国康复理论与实践

ObjectiveTo observe the temporary loss (re-falling) of knee range of motion (ROM) during rehabilitation after arthrolysis for post-traumatic knee stiffness, and analyze the factors related to it. MethodsFrom July, 2016 to September, 2019, 64 patients (68 knees) in Beijing Bo'ai Hospital accepted minimally invasive arthrolysis for post-traumatic knee stiffness, and were followed up for twelve months. ROM of flexion and extension of knee was measured before operation, and one, six and twelve weeks, and six and twelve months after operation; while they were asssessed with Hospital for Special Surgery Knee Score (HSS). Multivariate Logistic regression was performed on re-falling. ResultsThe ROM and HSS score improved as a whole after operation; however, HSS score improved constantly, but ROM decreased six weeks after operation compared with that one weeks after operation, involving 46 knees of 44 cases. Arthrolysis longer than 12 months from primary injuries, multiple complicated fracture and history of infection were the risk factors for re-falling (OR > 8.058, P < 0.05). ConclusionMinimally invasive arthrolysis is effective on knee function after arthrolysis for post-traumatic knee stiffness. However, re-falling of ROM may happen during rehabilitation. Delay of operation, multiple complicated fracture and history of infection may increase the risk of re-falling.

Comparative effect of different neuromuscular exercises on pain and motor function of knee in patients with early knee osteoarthritis / 中国康复理论与实践

ObjectiveTo compare the effect of proprioceptive neuromuscular training methods on pain and motor ability of knee in patients with early knee osteoarthritis (KOA) . MethodsFrom November, 2022 to May, 2023, 60 early KOA patients from Beijing Bo'ai Hospital and community were randomly divided into groups A, B and C, with 20 patients in each group. Group A received proprioceptive neuromuscular facilitation (PNF), group B received neuromuscular exercise (NEMEX), and group C received PNF and NEMEX, for six weeks. They were assessed with Visual Analogue Scale for pain (VAS), angle reappearance test, difference of pre-motor reaction time (VM-VL), active range of motion (AROM) of knee flexion, 10-meter walk test (10MWT), and Knee Injury and Osteoarthritis Outcome Score (KOOS) before and after treatment. ResultsAll the indexes improved in all the groups after treatment (|t| > 2.532, P < 0.05). Among the groups, the VAS score was the least in group A, and then groups C and B; the angle reappearance error was the least in group C, and similar in groups A and B; the VM-VL was the least in groups A and C, followed by group B. ConclusionPNF, NEMEX and PNF+NEMEX can relieve the pain and improve the motor function of knee in patients with early KOA, however, PNF is the most effective on relieving pain, and PNF+NEMEX is the most effective on improving knee function.

Characterastics of muscle architectural parameters for early knee osteoarthritis in middle-aged and elderly women / 中国康复理论与实践

ObjectiveTo observe the architectural parameter changes of the muscles around the knee in middle-aged and elderly women with early knee osteoarthritis (KOA) by musculoskeletal ultrasound, and to clarify the indicators of muscles that affect early KOA. MethodsFrom January to August, 2022, 20 healthy middle-aged and elderly healthy women (controls) and 20 middle-aged and elderly women with unilateral early KOA (KOA group) were recruited through Beijing Bo'ai Hospital, to measure muscle thickness of the popliteus muscle, the muscle thickness and the pennation angle of the quadriceps, as rectus femoris, vastus intermedius, vastus lateralis, vastus medialis longus and vastus medialis oblique. ResultsCompared with the healthy limb of KOA group, and the controls, the muscle thickness of vastus medialis longus, vastus medialis oblique and popliteus muscle of the affected limb of KOA group became thinner (t > 2.133, P < 0.05); the proportion of thickness of vastus medialis oblique to thickness of vastus lateralis became smaller (t > 3.660, P < 0.05). The pennation angle was smaller in the affected limb of KOA group than in the matched dominant side of the controls (t = 3.101, P < 0.05). Logistic regression analysis showed that the muscle thickness of vastus medialis oblique (OR = 0.235, 95%CI 0.068 to 0.805, P = 0.021) and popliteus muscle (OR = 0.387, 95%CI 0.152 to 0.980, P = 0.045) were related to the onset of early KOA. ConclusionThe thickness of vastus medialis longus, vastus medialis oblique and popliteus muscle decrease, and the balance of the strength of vastus medialis oblique and vastus lateralis weakens in the affected limbs of the middle-aged and elderly women with early KOA. The thickness of vastus medialis oblique and popliteus muscle are protective factors for onset of KOA.

Epidemiological and clinical characteristics of pediatric lower extremity amputation and functional rehabilitation / 中国康复理论与实践

ObjectiveTo analyze the epidemiological and clinical characteristics of children's lower extremity amputation and amputation rehabilitation, and to explain the causes of children's amputation and the complications after amputation. MethodsFrom January, 2016 to March, 2021, 51 amputation related children were retrospectively analyzed. The correlation between the cause of amputation and complications post amputation were analyzed. ResultsTraumatic amputations accounted for 58.82%, and the main cause was traffic accidents (70%). Amputations caused by diseases accounted for 41.18%, and the main cause was congenital limb deformities (80.95%). Traumatic amputation was more likely to have stump complications than expected (P < 0.05). The possibility of stump complications after disease-specific amputation was lower than expected (P < 0.05). ConclusionTraffic trauma is the main cause of amputation in children and is characterized clinically by a high incidence of unsatisfactory stumps, mainly due to soft tissue abnormalities, and most cases require stump revision to improve the poor residuals for prosthetic restoration of ambulation. Congenital pseudarthrosis of the tibia is the main cause of disease-specific amputation, and the outcome of amputation often cannot be definitely avoided even after long-term limb preservation treatment.

Susceptibility gene polymorphisms of primary knee osteoarthritis: a systematic review / 中国康复理论与实践

ObjectiveTo conduct a systematic review of the susceptibility gene polymorphism sites of primary knee osteoarthritis (PKO). MethodsThe literature on genetic susceptibility and gene polymorphisms of PKO were retrieved from PubMed, Web of Science, CNKI, Wanfang Data, and China Biomedical Literature Database from establishment of the library to December, 2020, and systematically reviewed. ResultsA total of 42 papers on the polymorphism sites of human PKO susceptibility genes were included, involving cellular signaling pathways related to PKO pathogenesis, including inflammatory response, receptor signaling pathway, transcription factor signaling pathway, bone-related signaling pathway, etc. Multiple gene polymorphism sites located in inflammatory factor genes, chemokine genes, Toll-like receptor genes, transcription factor genes, obesity-related genes, and bone-related genes. ConclusionInflammatory factor genes and bone-associated allele polymorphisms are likely to be related to PKO susceptibility.

Proteomics study on biomarkers for heterotopic ossification secondary to traumatic brain injuries.

OBJECTIVE: To identify differentially expressed serum proteins that could serve as sensitive biomarkers of heterotopic ossification in patients with traumatic brain injury. METHODS: From August 2014 to December 2015, 18 patients with traumatic brain injury were enrolled in the study, and blood samples were collected. Patients with traumatic brain injury were divided based on the presence (n=9 patients, heterotopic ossification group) or absence (n=9 patients, traumatic brain injury group or control group) of heterotopic ossification. Protein expression profiles were compared using 2-dimensional electrophoresis. Differentially expressed proteins were examined using matrix-assisted laser desorption/ionization and time-of-flight tandem mass spectrometry (MALDI-TOF/TOF). The differentially expressed proteins identified were further confirmed by Western blotting. RESULTS: Seven protein spots were differentially expressed between heterotopic ossification and traumatic brain injury groups in 2-dimensional electrophoresis analysis. Vitamin D binding protein (Gc protein), retinol binding protein 4 (RBP4) and haptoglobin expression decreased significantly in the heterotopic ossification group compared with the control group (p < 0.05), and this was further confirmed by Western blotting. CONCLUSION: Lower levels of expression of Gc protein, RBP4 and haptoglobin may be closely related to heterotopic ossification after traumatic brain injury. These proteins may be potential biomarkers of heterotopic ossification secondary to traumatic brain injury.

The role of isokinetic muscle strength training in rehabilitation after rotator cuff repair / 中华物理医学与康复杂志

Objective:To explore the effect of isokinetic strength training on post-operative rehabilitation of rotator cuff injury after arthroscopy.Methods:Forty patients who had received arthroscopic repair of a rotator cuff tear no less than 3 months previously and who had normal joint movement were selected and randomly divided into a routine training group (the control group) and an isokinetic strength training group (the experimental group), each of 20. Both groups did internal and external rotation strength training with Thera-Band elastic bands, 10-20 times/session, 3 sessions/day. The experimental group additionally underwent isokinetic strength training of the shoulder for 15-20 minutes twice a week. Isokinetic strength tests were performed after 3 and 6 months at test speeds of 60°/s and 180°/s. The evaluation indexes included the internal and external rotation peak torque, peak TQ/BW, the deficit of the affected shoulder joint, the peak torque difference and peak TQ/BW difference before and after training.Results:Both groups had improved significantly after the treatment, but the improvement in the experimental group was significantly greater than in the control group, on average.Conclusion:Isokinetic muscle strength training is helpful to recover strength after arthroscopic repair of a rotator cuff injury, especially the rapid external rotation muscle strength. It is worthy of clinical application.

Diagnosis and treatment of ventricular septal defect with infective endocarditis in 40 patients / 中国胸心血管外科临床杂志

@#Objective    To analyze the diagnosis and treatment of patients with ventricular septal defect complicated with infective endocarditis. Methods    We retrospectively analyzed the clinical data of 40 patients with ventricular septal defect complicated with infective endocarditis in our hospital from 2001 to 2016. There were 25 males and 15 females, aged 20-62 (39.92±11.16) years. They were divided into two groups according to the duration from admission to surgery: a group A (an early operation group whose surgery was performed within 7 days after admission) and a group B (a conventional treatment group with the duration from admission to surgery>7 days). Among them, there were 27 patients in the group A including 15 males and 12 females with an average age of 39.56±11.80 years, and 13 patients in the group B including 10 males and 3 females with an average age of 40.69±10.13 years. All patients were examined by echocardiogram and blood bacterial culture to investigate their etiology, echocardiogram results and treatment status. And the clinical data of the two groups were compared. Results    Two patients died before operation in the group B, one died of heart failure, and one cerebral infarction. No reoperation during hospitalization, cerebral infarction, thromboembolism or other complications occurred. The ventilation time in the group A was significantly shorter than that in the group B (18.00±14.85 h vs. 31.00±29.57 h, P=0.015). There was no statistical difference in the extracorporeal circulation time, myocardial block time, or postoperative hospital stay between the two groups (P>0.05). After discharge, the patients continued antibiotic therapy for 3-6 weeks. Patients were followed up for 12-127 (75.74±6.01) months, 1 died of malignant tumors in the group A, 1 developed atrial fibrillation and 1 developed cardiac insufficiency in the group B, and the rest of patients did not complain of obvious discomfort. There was no residual shunt, recurrence of infective endocarditis, reoperation, postoperative stroke or thromboembolism. Conclusion    Preoperative echocardio-graphy and blood bacteriological culture are helpful for the diagnosis and treatment of patients with ventricular septal defect complicated with infective endocarditis. Early surgery is safe and effective for these patients, and can improve the long-term survival rate.

The matching analysis of the tibial osteotomy and the imported prosthesis components of the Han and Uygur populations / 中华骨科杂志

Objective To compare the anatomical differences of tibia osteotomy between Han and Uygur populations and to analysis their compatibility with imported prosthesis component.Methods Two hundred patients (400 knees) were selected from the outpatients and healthy volunteers of the non-knee joint disease from September 1,2012 to December 1,2014,with 86 men (172 knees) and 114 women (228 knees).The average age is 44.64-10.8 years (range 21-68 years old).According to the populations,the subjects were divided into Han group and Uygur group.Furthermore,each group was divided into male subgroup and female subgroup.A full-length CT scan of the lower limb was conducted to reconstruct the knee joint in the workstation.The tibial osteotomy was simulated in total knee arthroplasty.The transverse diameter of the tibial cross section,the longitudinal depth of the medial platform and the depth of the lateral platform were measured.The front and back diameter and aspect ratio of the osteotomy were calculated.There parameters were compared between the Han and Uygur groups.Five mm tolerance range method was used to analysis the cover rate of the following three kinds of commercially imported prosthesis,namely Depuy,Link and Zimmer.Results The mean value of the tibial cross section were 72.3±4.3 mm,50.7±3.1 mm,47.8±3.0 mm,49.3±2.9 mm and 0.682±0.021 in Han group,while those were 74.5±4.8 mm,51.4±3.0 mm,48.6±2.8 mm,50.0±2.9 mm and 0.672±0.020 in Uygur group,respectively.Except the aspect ratio,the average value of each parameter in Uygur group was greater than that in the Han group with statistically significant differences between the two populations.The cover rate of the three kinds of prosthesis tibial component were 53.0％,37.0％ and 40.0％ for Han group,but 61.0％,43.0％ and 42.5％ for Uygur group.Depuy prosthesis was fit for the Uygur population better.Conclusion The geometry and anatomy of proximal tibia in Chinese showed significant difference between Han and Uygur populations.The mean covering rates of the imported tibial components were low in the dimensions of the resected surface.We can improve the prosthesis and the matching degree by adjusting the parameters or increasing the model set.

Influence of tea pigment on cardiac activity in exsomatized toads of myocardial ischemia / 重庆医学

Objective To observe the influence of tea pigment on myocardial contractility,electrocardiogram(ECG) and heart rate in exsomatized toads under the condition of myocardialischemia.Methods Sixty toads were divided into the normal exsomatized toad heart group(A) and myocardial ischemia toad heart(B).Then the group A was re-divided into the Ringer's solution group (A1),tea pigment low dose(200 mg/L) group(A2) and the high dose(400 mg/L) group(A3);the group B was re-divided into the pituitrin model group(B1),pituitrin + tea pigment low dose(200 mg/L) group(B2) and high dose(400 mg/L) group(B3).The BL-420S biological function experiment system was used to record the myocardial contractile force and ECG change curve of exsomatized toad.Results Compared with the group A1,the myocardial contractility in the group A3 was obviously increased(P＜0.05),the difference in the group A2 had no statistical significance(P＞0.05);the QRS peak value of ECG and heart rate had no statistically significant difference(P＞0.05);compared with the group A1,the myocardial contractility,ECG QRS peak value and heart rate in the group B1 were significantly decreased(P＜0.05);compared with the group B1,the myocardial contractility,ECG QRS peak value and heart rate in the group B2 and B3 were significantly increased(P＜0.05).Conclusion Tea pigment can obviously improve the decrease of the exsomatized toad cardiac activity caused by myocardial ischemia.

Perioperative characteristics of hip fractures and effects of early rehabilitation in elderly patients / 中华老年医学杂志

Objective To investigate the perioperative characteristics of hip fractures and the effects of early rehabilitation in elderly patients. Methods Clinical data of 123 elderly patients admitted to our department from January 2012 to January 2014 were retrospectively analyzed. Patients were divided into a rehabilitation group and a control group ,based on whether rehabilitation therapy was offered.Comparison was made between the two groups on postoperative mortality and postoperative complications. Results Of 123 patients ,there were 51 males and 72 females ,with a mean age of (83.5 ± 4.8)years(aged 67~96 years).Femoral fractures were seen in 32 patients and femoral intertrochanteric fractures in 91 patients.Before operation ,112 (91.1% ) patients had concomitant diseases. There were significant differences in postoperative complications and one-year mortality after operation between patients receiving early rehabilitation and controls (5/60 or 8.3% vs.14/63 or 22.2% ,4/60 or 6.7% vs.13/63 or 20.6% ,χ2=4.539 and 5.034 ,P=0.033 and 0.025 , respectively ). Conclusions Elderly hip fracture patients have many concomitant diseases before operation.With appropriate perioperative management ,well-chosen methods of anesthesia and surgery ,and early postoperative rehabilitation measures ,the incidence of perioperative complications and one-year mortality can be decreased ,and desirable surgical outcomes can be attained.

Expression of Fibrogenic Cytokine and Inflammatory Cytokine in Frozen Shoulder / 中国康复理论与实践

Objective To explore the role of fibrogenic cytokines and inflammatory cytokines in the pathogenesis of frozen shoulder. Methods From September, 2014 to April, 2016, 20 patients with frozen shoulder accepted arthroscopic surgery were included, ten of them were diagnosed as primary frozen shoulder (group A), the other ten were secondary frozen shoulder (group B). Other ten patients undergo-ing shoulder arthroscopy for instability (4 cases), rotator cuff injury (3 cases) and subacromial impingement (3 cases) were as the controls (group C). The mRNA levels of matrix metalloproteinase (MMP) 1, MMP3, tumour necrosis factor-α (TNF-α), interleukin (IL)-1, IL-6, IL-8, granulocyte-macrophage colony stimulating factor (GM-CSF) and M-CSF in synovium were analyzed with quantitative polymerase chain reaction. Results The expression of mRNA of MMP1, MMP3, TNF-α, IL-1, IL-6, IL-8, GM-CSF and M-CSF were more in group A and group B than in group C (P0.05). Conclusion The fibro-genic cytokines and inflammatory cytokines may play a role in the pathogenesis of frozen shoulder.

Effect of Standardized Pain Management on Old Patients after Hip Fracture Surgery / 中国康复理论与实践

Objective To observe the effects of standardized pain management on old patients with hip fracture. Methods From January, 2015 to June, 2016, 75 old patients (more than 58 years old) with hip fracture were randomly divided into control group (n=37) and observa-tion group (n=38). The control group accepted routine pain management, while the observation group accepted standardized pain manage-ment. They were assessed with Visual Analogue Score (VAS) of the most intensive pain, and their scores for satisfaction were compared. Re-sults There was no significant difference in VAS between two groups before operation (Z=0.845, P>0.05). The VAS was significantly lower in the observation group than in the control group postoperatively (Z=5.427, P<0.001). The scores of satisfaction was more in the observa-tion group than in the control group (t=21.346, P<0.001). Conclusion Standardized pain management can significantly reduce perioperative pain in old patients after hip fracture surgery, and improve the satisfaction.

Arthroscopic Treatment for Acute Avulsion Fracture of Posterior Cruciate Ligament:Two Cases Report / 中国康复理论与实践

Objective To explore the efficacy of arthroscopic treatment for acute avulsion fracture of posterior cruciate ligament (PCL) using double titanium plate TightRope. Methods From December 2014 to January 2015, two cases with acute avulsion fracture of PCL were treated with double titanium plate TightRope under arthroscopy, after assessment of three dimensional reconstructive CT and MRI. Rehabili-tation was carried out after operation. Results One case succeeded with double titanium plate TightRope, and rehabilitation could be per-formed early postoperatively. Another case failed in TightRope fixation, and accepted two internal hollow screws fixation instead. Rehabili-tation was delayed until two weeks postoperatively. The function of the knee was satisfactory in the former patient after three months, who could extend the knee in a normal range, without pain or locking. The same effect was gained in the latter patient after four months. Conclu-sion For acute tibial avulsion fracture of PCL with larger and intact fragment without osteoporosis, arthroscopic restoration and fixation with double titanium plate TightRope offers the opportunity to achieve anatomic reconstruction and rigid fixation for early rehabilitation in adult patients.

Teaching Experience of Orthopaedic Rehabilitation Resident Standardization Training / 中国康复理论与实践

Orthopaedic rehabilitation is an important part of rehabilitation resident standardization training, that is complex and unique. Introduction of the discipline, as well as optimizing teaching methods, clinical practice and test are very important for a satisfactory out-come, such as combination of theory and practice, and systematical rehabilitation procedures, principles and operation.

Effect of Free Radical Scavenger on Prevention of Traumatic Heterotopic Ossification in Rabbits / 中国康复理论与实践

Objective To compare the effects of non-steroidal anti-inflammatory drugs (NSAIDs) and free radical scavengers (FRS) on formation of traumatic heterotopic ossification (HO) in rabbits. Methods 48 New Zealand rabbits were randomly divided into control group (n=12), NSAIDs group (n=12), FRS group (n=12) and combination group (n=12). The model of traumatic HO was established, and the NSAIDs group, FRS group and combination group were administered indometacin intragastrically, edaravone intravenously and both, re-spectively, while the control group was administered normal saline for 4 weeks. The incidence and severity of HO were observed with X-ray 8 and 12 weeks after modeling. Results 8 and 12 weeks after operation, the incidence of HO was 33.3%and 41.7%in the NSAIDs group, 43.0%and 45.8%in the FRS group, 29.2%and 37.5%in the combination group, and 70.8%and 75.0%in the control group, respectively. The incidence and severity of HO in all the treatment groups were significantly less than those in the control group (P0.05). Conclusion The systemic application of FRS may prevent the formation of HO effectively, similar with the NSAIDs. There is no synergistic effect between them.

Effect of Free Radical Scavenger on Prevention of Traumatic Heterotopic Ossification in Rabbits / 中国康复理论与实践

@#Objective To compare the effects of non-steroidal anti-inflammatory drugs (NSAIDs) and free radical scavengers (FRS) on formation of traumatic heterotopic ossification (HO) in rabbits. Methods 48 New Zealand rabbits were randomly divided into control group (n=12), NSAIDs group (n=12), FRS group (n=12) and combination group (n=12). The model of traumatic HO was established, and the NSAIDs group, FRS group and combination group were administered indometacin intragastrically, edaravone intravenously and both, respectively, while the control group was administered normal saline for 4 weeks. The incidence and severity of HO were observed with X-ray 8 and 12 weeks after modeling. Results 8 and 12 weeks after operation, the incidence of HO was 33.3% and 41.7% in the NSAIDs group, 43.0% and 45.8% in the FRS group, 29.2% and 37.5% in the combination group, and 70.8% and 75.0% in the control group, respectively. The incidence and severity of HO in all the treatment groups were significantly less than those in the control group (P<0.05), and there was no significant difference among the treatment groups (P>0.05). Conclusion The systemic application of FRS may prevent the formation of HO effectively, similar with the NSAIDs. There is no synergistic effect between them.

Anterolateral Ankle Impingement Syndrome (review) / 中国康复理论与实践

Ankle sprain without fracture or dislocation, accompanied by repeated ankle swelling is called as Anterolateral Ankle Im-pingement Syndrome. It is a major reason of chronic ankle pain and received extensive attention. This paper summarized its pathogenesis, clinical manifestations, diagnosis and treatment.

Establishment of Animal Model of Subchondral Bone Micro-fracture with Knee Joint Impact System in Rabbits / 中国康复理论与实践

Objective To develop a knee joint impact device to produce animal model of subchondral bone micro-fracture in rabbits. Methods A knee joint impact device was designed. 12 New Zealand rabbits were divided into group A (n=6) and Group B (n=6). In the group A, 6 patellar-femoral joints of the 6 rabbits were impacted (1.74 kg from height of 30 cm). In the group B, 6 femoral condyles of the 6 rabbits were impacted (1.14 kg from height of 28 cm). All the rabbits were evaluated with X-ray and MRI post injury. The femora of all the rabbits were observed with HE staining. Results No fracture line was found in all the animals with X-rays. The MRI of the 6 knee joints in the group A showed low signal intensities on T1 weighted, T2 weighted and fat suppression images. Histopathology demonstrated integrated cartilage and sunchondral bone plate, micro-fractures of cancellous and bleeding in marrow. The MRI of the 5 knee joints in the group B showed low signal intensities on T1 weighted images and high signal intensities on T2 weighted and fat suppression images. Histopathology demonstrated integrated cartilage and sunchondral bone plate, micro-fractures of cancellous and bleeding in marrow. No disorder was found with MRI and histology in the contral sides. Conclusion The impact device of the knee joint can produce controllable and reproducible sub-chondral bone micro-fracture in rabbits.