Kosuke Ogata

Nutritional Pathways of the Intervertebral Disc: An Experimental Study Using Hydrogen Washout Technique

The pathways of material transfer to the intervertebral disc were studied in adult dogs by measuring diffusion of hydrogen molecules in the nucleus pulposus before and after disruption of the route through the annulus fibrosus and before and after disruption of the end-plate route. The disruption of the end-plate route, even if the separation of the bone-disc interfaces was only in the central two-thirds of one side, caused significantly greater decrease in the rate of hydrogen washout than the disruption of the annulus route. Hitologically, the bone-cartilage interface was frequently perforated by marrow cavity and vascular buds. These findings suggest that the end-plate route is a major pathway for material transfer to the intervertebral disc.

Measurements of length and tension patterns during reconstruction of the posterior cruciate ligament

The twofold purpose of this study was to develop an intraoperative technique to assess isometric positioning of posterior cruciate ligament grafts and to demonstrate the rationale for postoperative immobilization of the knee in full extension after a posterior cruciate ligament reconstruction. Multiple femoral fixation sites were se lected on the medial intercondylar notch and the pos terior cruciate ligament substitute was assessed for changes in length and tension at each of these sites during knee flexion from 0° to 120°. The most isometric and isotonic femoral fixation site was localized over a small area slightly distal to the center of the medial intercondylar notch surface. This isometric point can be identified intraoperatively using recognizable surface markers within the knee. When a posterior stress was applied to the proximal tibia, the posterior cruciate ligament substitute showed the least increase in tension and length when the knee was locked in full extension for all of the potential femoral attachment sites assessed. This suggests that postoperative immobilization should be maintained in full extension to limit the stress placed on the posterior cruciate ligament reconstruction.

The effect of surgical dissection on regional blood flow to the ulnar nerve in the cubital tunnel.

Regional blood flow to the ulnar nerve within the cubital tunnel of nonhuman primates was determined before and after surgical dissection by use of the hydrogen washout technique. The results indicate that anterior transposition is associated with a significant decrease in regional blood flow to the ulnar nerve for a period of at least three days. This relative ischemia was not noted following arcuate ligament incision or after medial humeral epicondylectomy. Vascular injection studies showed an abundant extrinsic arterial supply to the ulnar nerve, especially just distal to the groove that was apparently compromised during the anterior transposition.

Effect of tibial slope or posterior cruciate ligament release on knee kinematics.

An experimental study using fresh human cadaver knees was designed to evaluate the effect of partial posterior cruciate ligament release or posterior tibial slope on knee kinematics after total knee arthroplasty. Varus and valgus laxity, rotational laxity, anteroposterior laxity, femoral rollback, and maximum flexion angle were evaluated in a normal knee, an ideal total knee arthroplasty, and a total knee arthroplasty in which the ligaments were made to be too tight in flexion. The total knee arthroplasty specimens then were subjected to either partial posterior cruciate ligament release or increased posterior tibial slope, and the tests were repeated. Posterior tibial slope increased varus and valgus laxity, anteroposterior laxity, and rotational laxity in the knee that had flexion tightness. Posterior cruciate ligament release corrected only anteroposterior tightness, and had no effect on the abnormal collateral ligament tightness. Increased posterior tibial slope significantly improved varus and valgus laxity and rotational laxity in the knee that was tight in flexion more than with release of the posterior cruciate ligament. Therefore increasing posterior tibial slope is preferable for a knee that is tight in flexion during total knee arthroplasty.

A new three-dimensional osteotomy for cubitus varus deformity after supracondylar fracture of the humerus in children.

In the past, supracondylar osteotomy for the correction of cubitus varus deformity has been associated with a high failure rate and significant complications, even in simple lateral closing wedge osteotomy. This is because the supracondylar area is thin and fixation is difficult to maintain. In cubitus varus deformity, not only medial, but posterior, tilt and internal rotation of the distal fragment also frequently occurs. To correct all these deformities and to achieve a wide bony contact and more rigid fixation than simple lateral closing wedge osteotomy, we propose a new three-dimensional osteotomy. Among 12 patients who received this osteotomy, 11 had an excellent result and one had a good result.

Short arm of chromosome 1 aberration recurrently found in pigmented villonodular synovitis

Pigmented villonodular synovitis (PVNS) is a relatively uncommon benign lesion that is characterized by diffuse synovial proliferation, mainly occurring in knee joints. Cytogenetic reports about this lesion are few and they describe the presence of numerical and structural chromosome aberrations. We obtained PVNS tissue from the left knee joint of a 53-year-old female, and performed cytogenetic analysis. Fluorescence in situ hybridization (FISH) was also performed by using the formalin fixed, paraffin embedded PVNS tissue. Two seemingly unrelated clones were found: the first clone had structural abnormalities of chromosome 1, 3, and 18, and the second one had trisomy 7 as a sole numerical abnormality. FISH using a chromosome 7 specific alpha-satellite DNA probe revealed that interphase nuclei possessed two or three signals. We describe the clonal aberrations found in a case of PVNS. The deleted lesion of the chromosome 1 (1p10-1p31.3) includes the locus of coagulation factor III gene (1p22-p21), and the coagulation factor V (1q21-q25) locus includes another breakpoint that is 1q25. In addition, recurrent structural abnormalities at the short arm of chromosome 1 have been reported. These facts might play some role in the hemorrhagic tendency and histogenesis of these lesions.

The acute effects of periosteal stripping and medullary reaming on regional bone blood flow.

The immediate effects of surgical dissection on regional bone blood flow were studied using the hydrogen washout technique and the results were compared in mature and immature rabbits. Epiphyseal circulation in young animals was eliminated by stripping the epiphyseal periosteum, and even in mature rabbits epiphyseal blood flow was markedly reduced by periosteal stripping. This suggests that after skeletal maturity blood supply crossing from the metaphysis into the epiphysis is limited. The blood flow rate was not altered by wide reaming of the epiphyseal center in either young or old animals. The rates of bone blood flow in the metaphysis and diaphysis were not altered by separate periosteal stripping or medullary reaming in either age group. Combined reaming and stripping eliminated blood flow in the diaphyseal cortical bone, but in the metaphysis fairly rapid blood flow remained even after reaming and periosteal stripping were done. These findings suggest that arterial supply and venous drainage traverse both endosteal and periosteal surfaces, and either system is capable of sustaining adequate bone tissue circulation.

Congenital vertical talus and its familial occurrence: an analysis of 36 patients.

Thirty-six patients (57 feet) showing congenital vertical talus were treated at the St. Louis Unit of the Shriners Hospital between 1958 and 1978. A high incidence of congenital hip dislocatiom, arthrogryposis, congenital hypoplasia of tibia and CNA disorders was noted as associated abnormalities. These patients are classified in 3 groups: (I) primary isolated form (16 patients); (II) associated form without neurological deficit (12 patients); (III) associated form with neurological deficit (8 patients). Fifty per cent of the patients with primary isolated form had positive family history of foot deformities in their first degree relatives. Familial incidence of congenital vertical talus was observed in 2 families studied. Genetic factors may play an important role in the etiology of the primary isolated form of congenital vertical talus. The current treatment is a one-stage open reduction of the talonavicular dislocation, combined with a posterior release. A subtalar bone block is often imperative to maintain correction. Cast correction alone has never succeeded as the definitive treatment of this condition.

The effect of varus stress on the moving rabbit knee joint.

Unicompartmental osteoarthritis was produced by applying varus stress to moving rabbit knee joints. Degenerative changes were confined to the medial tibial and the medial femoral articular surfaces. Within the range of varus stress used, duration appears to be more important than magnitude of varus stress in determining the severity of cartilage damage. The calcified zone remained histologically unchanged despite advanced changes in the noncalcified zone superficial to the tidemark. Intrachondral degenerative cysts were frequently found in the basilar layers of the noncalcified cartilage adjacent to the tidemark where shear stresses were likely to be highest and diffusible nutrients least available. Highly cellular cartilaginous tissue was noted in the subchondral marrow spaces in the specimens with advanced cartilage degeneration. These areas appeared to be continuous with the overlying degenerated cartilage through gaps in the calcified cartilage. Subchondral bone did not show remarkable trabecular thickening despite advanced degenerative changes in the articular cartilage.

Interlocking wedge osteotomy of the proximal tibia for gonarthrosis.

Modification of the lateral closing wedge osteotomy of the proximal tibia is described for gonarthrosis associated with varus deformities. In this procedure, the anterior and posterior cortices are left attached to the distal and proximal fragments respectively when the bone wedge is removed. The defect is closed by applying valgus stress and medial rotation to the distal fragment so that the tibial tubercle advances anteriorly and the posterior cortex of the proximal fragment overrides the distal fragment. Contact area and stability at the osteotomy site are increased by an interlocking effect of the cortices and the stress under the patella is reduced by anterior advancement of the tibial tubercle. Satisfactory results have been obtained in 36 cases followed for one to three years with few complications.