A Comparison of the Fixation Strengths Provided by Different Intraosseous Tendon Lengths during Anterior Cruciate Ligament Reconstruction: A Biomechanical Study in a Porcine Tibial Model

BACKGROUND: The purpose of this study was to determine the tibial fixation strength provided by different intraosseous soft tissue graft lengths within the tibial tunnel. METHODS: Porcine tibial bones and digital flexor tendons were used for testing. Bone mineral densities of proximal tibial medial condyles were measured, and two-strand tendon bundles of 8 mm diameter were used. An intraosseous graft length of 2 cm was used in group 1 (n = 10), and a graft length of 4 cm was used in group 2 (n = 10). Tunnels were 4 cm in length and 8 mm in diameter. Tibial fixation was performed using a suture tied around a screw post with a washer and an additionally inserted 7 x 20 mm bioabsorbable screw. After applying preconditioning loading of 10 cycles, 1,000 cycles between 70-220 N were applied at a frequency of 1 Hz. Graft slippage and total graft movement were recorded. Ultimate tensile strength was measured by pull-out testing at an Instron crosshead speed of 1,000 mm/min. RESULTS: No significant intergroup difference was found for total graft movement after cyclic loading (slippage in group 1, 1.2 mm and group 2, 1.2 mm, respectively, p = 0.917; and total graft movement in group 1, 3.3 mm and group 2, 2.7 mm, respectively, p = 0.199). However, mean ultimate tensile strength in group 2 was significantly higher than that in group 1 (group 1, 649.9 N; group 2, 938 N; p = 0.008). CONCLUSIONS: In a porcine model, ultimate tensile strength was greater for a 4 cm long intraosseous flexor tendon in the tibial tunnel. However, no intergroup difference in graft slippage or total graft movement was observed. The results show that a 2 cm intraosseous graft length in the tibial tunnel is safe and has sufficient strength (> 450 N) for adequate rehabilitation after anterior cruciate ligament reconstruction.

Biomechanical Effect of Cyclic Loading on the Reconstructed Posterior Cruciate Ligament: Comparison between Inlay and Transtibial Technique / 대한정형외과학회잡지

PURPOSE: To compare differences in the biomechanical characteristics of posterior cruciate ligament (PCL) reconstructed by the inlay and transtibial techniques. MATERIALS AND METHODS: PCL reconstruction was performed in 12 pairs of porcine hindlimbs using the inlay and transtibial techniques. Cyclic load testing was carried out in three steps. The first step was 750 cycles at 35-350 N, the second 10,000 cycles at 35-350 N, and the third 10,000 cycles at 45-450 N. Length changes of the reconstructed PCLs were measured and the sites of rupture observed. RESULTS: Among the 10 pairs of limbs that completed the test procedure, the graft ruptured before step 3 in all specimens except one in the transtibial group, and seven specimens completed step 3 testing in the inlay group. Comparing the load elongation curves obtained in step 2 tests, more elongation of the graft was evident in the transtibial group (p<0.05). The site of rupture was proximal 1/3 (2 specimens) or distal 1/3 (1) to the graft in the inlay group, and in the distal 1/3 for all specimens of the transtibial group. CONCLUSION: These results suggest that the tibial tunnel orifice renders a risk of attritional rupture to the graft in the transtibial technique. In this respect, the inlay technique has a biomechanical advantage over the transtibial technique.

Retensioning and Augmentation of Posterior Cruciate Ligament

No Abstract Available.

Healing potential of the transected posterior cruciate ligament of the rabbit / 대한정형외과학회잡지

PURPOSE: This study was undertaken to elucidate the natural healing potential in posterior cruciate ligament (PCL) injury using histological and biomechanical methods. MATERIALS AND METHODS: PCLs of 92 rabbits were cut partially or completely cut on one side. In Group I, 75% of the PCL was cut preserving the synovium partially. In Group II, the PCL and synovium were completely severed. Investigations were performed by gross inspection, histological examination after Hematoxylin-Eosin (HE) staining and tensile stress testing using an Instron. RESULTS: Continuity of the ligaments began to appear at 2 weeks in group I and at 12weeks in group II. Proliferation of fibroblasts and vessels were observed in HE stained ligaments at 6 and 12 weeks in both groups. The ultimate tensile strength in group I was .3% and in group II 33.1% at 12 weeks. CONCLUSION: Although the mechanical properties of the regenerated ligaments were poor, this study demonstrats that the rabbit PCL has healing potential irrespective of the degree of injury.

Magnetic Resonance Imaging on Posterior Cruciate Ligament Injury: Can the PCL hea

PURPOSE: The aim of this study was to elucidate the continiuty of ligament in chronic injury of the pos- terior cruciate ligament(PCL). MATERIALS AND METHODS: Magnetic resonance imaging(MRI#) of twenty-six PCL injury patients with grade II or III laxity and more than 5mm side to side difference on stress radiographs were reviewed in terms of ligamentous continuity and thickness of the ligament at average 7.2 months(range:1-36) after injury. RESULTS: Eighteen PCLs(69%) showed continuity of PCL. When thickness of the ligament in cases without continuity was rated as zero, the average thickness of the PCLs as compared to intact portion of the ligament increased as the time from injury elapsed; 16.4% in 0 2 months group(7 cases), 30.0% in 3- 5 months group(6 cases), 53.8% in 6-8 months group(9 cases) and 80.0% in over 9 months group(4 cases). CONCLUSTION: More than two thirds of PCLs in symptomatic chronic injury showed ligamentous continuity on MRI. The longer the interval from injury was, the thicker the PCL was.

Development of Extor Pins for Extor External Fixator / 대한정형외과학회잡지

We developed Extor pins for Extor external fixator, it made of stainless steel and applied it clinically to manage open fractures and chronic osteomyelitis from December, 1993 to January, 1995. The main aim of present study is to compare the mechanical strength and biocompatibillity between Extor pins and AO Schanz pins, and to determine the safety and possibility of clinical use. We performed the biomechanical test for bending, tension, and shearing of pin itself using universal testing machine (LR5OK) and pullout test in cadeveric cortical femur to determine the bone holding power. There was no significant difference between Extor and AO Schanz pin (p>0.05). Clinically, the incidence of pin site infection, pin lossening, radiological rarefaction, and pathological change were not different significantly (p>0.05). Although Extor pins are somewhat different from AO Shanz pins in material and design characteristics, we can find the safety and possibility of clinical use of Extor pins made in Korea.

Acetabular Anateversion of Normal Korean Adult Population / 대한정형외과학회잡지

The aim of investigation is to calculate the mean value of the acetabular anteversion of normal Korean adult after closure of growth according to different gender and sex age group, to find out any significant difference of the value of acetabular anteversion to some other variables such as age, height, weight and radiographic inclination(abduction angle) of acetabulum. Transverse pelvic computed tomography(CT) scans of 360 right hips with no known pathology were examined. The study population consisted of 12 groups by gender (male and female) and age(from third to eighth decade). The number of each group was thirty. The scanning slice nearest the middle region of the acetabulum (nearest through the center of the femoral head) on the scout film was chosen. A measuring point was assigned at the anterior edge of the acetabulum and second at the posterior edge. The line connecting these points was drawn. The angle formed by this line and the plane sagittal to the pelvis was determined as acetabular anteversion. The data analysis was run on a statistical analysis system(SAS). The mean value of acetabular anteversion 19.8±5.4 degrees(17.1±5.6 in males, 22.2±5.4 in females), it was greater significantly in females than in males (p=0.0001). The mean value of acetabular anteversion in third decade male group than the third, fourth and fifth decade group significantly(p < 0.05). The mean value of acetabular anteversion of Koreans was similar to Caucasians value. The value of acetabular anteversion was relatively releated to age. In conclusion, the acetabular anteversion of Korean females was larger than the Korean males. It was increased with aging. When we perform the total hip arthroplasty and pelvic osteotomy or reorientation procedure, we must consider the acetabular anteversion by different gender and age group.

Anterior Interpositional Grafting for Scaphoid Nonunion with Dorsal Instability Rattern / 대한정형외과학회잡지

In thirteen adult male patient with scaphoid nonunion associated with DISI(Dorsal intercalated Segment Instability) defined as scapholunate angle is greater than 70 degrees of the radiolunate angle is greater than 10 degrees, anterior interpostitional bone grafting has been performed. Surgical procedure: 1) Closed reduction of lunate(reduction of DISI) by volar flexing of the wrist and holding the position by Kirschner wire inserted obliquely through the radial styloid to lunate. 2) Radical curettage of nonunion site and intraoperative measurement of the gap in the scaphoid through volar approach. 3) A bicortical wedge shaped graft from the iliac crest was then impacted between the fragments. 4) Temporary K-wire fixation of the grafted scaphoid from the scaphoid tubercle to prevent distortion of nonunion site and loss of fixation. 5) A Herbert screw was then inserted. Results: Mean patient age was 24.5 years, and mean duration of nonunion before surgery was 19.4 months. Mean follow-up time was 22.6 months. The nonunion involved the middle one-third of scaphoid in 11 patients and distal one-third in 2 patients. The mean postoperative grip strength was 39.4kg by Dynamometer(PC-5303J). The mean postoperative range of motion was volar flexion 50.5 degrees; dorsiflexion 47.3 degrees. The scaphlunate angle decreased from a mean of 78.8 preoperatively to 52.9 degrees postoperatively. The radiolunate angle was decresed from a mean of 16.8 degrees prope- ratively to a mean of 1.8 degrees postoperatively. Union was obtained in all 13 cases, According to Herbert and Fisher's formulation, 2 excellent, 10 good and 1 fair results were obtained from our study. The results of the series suggest that treatment of scaphoid nonunion associated with DISI by this method is an effective method that reconstitutes scaphoid anatomy and promotes excellent wrist function.