ABSTRACTS 299

Unusual Anomaly of the Scapula Defined by Arthros- copy and Computerized Tomographic Arthrography. By John J. Callaghan, James J. York, Lawrence M. McNiesh, and Scott D. Gillogly. J Bone Joint Surg [Am] 1988;70:452-3.

Isolated anomalies or dysplasias of the articular surface or the neck of the scapula are uncommon, and if present are rarely disabling. Very little liter- ature exists on this problem. Arthroscopic and dou- ble-contract computerized tomographic arthrogra- phy findings were valuable in defining the anomaly in the 33-year-old policeman who is the subject of this report. The patient, who was right-hand domi- nant, had a several-month history of dislocation of the right shoulder on heavy lifting. Thereafter he had persistent pain and giving-way of the shoulder with overhead activity, even after strengthening ex- ercises. Physical examination revealed limited ab- duction and external rotation of both shoulders and a positive apprehension test on the right. Radio- graphs revealed dysplasia of both scapular necks and glenoid surfaces. Double-contract computer- ized tomographic arthrography revealed an en- larged labrum and the tightness of the capsule al- lowed only a small amount of contrast medium to be injected into the shoulder joint. Arthroscopy dem- onstrated excessive anterior excursion of the hum- eral head but no dislocation. Some difficulty was encountered in inserting the arthroscope through a posterior portal due to the tightness of the capsule. The labrum was found to be extremely wide and thick in its entire circumference. A large anterior labral tear was also demonstrated. At 1 year, the patient was able to work but still had some pain and giving-way of the shoulder. Anomalies of the artic- ular surface or the neck of the scapula are usually manifested clinically in older patients and usually occur bilaterally. The use of computerized tomo- graphic arthrography and arthroscopy enabled ac- curate definition of the anomaly in our patient. We do not consider labral excision in these patients, because the large labrum is probably the stabilizing structure.

The Effect of Cryopreservation on Canine Menisci: A Biochemical, Morphologic, and Biomechanical Eval- uation. By Steven P. Arnoczky, Cahir A. McDevitt, Mary Beth Schmidt, Van C. Mow, and Russell F. Warren. J Orthop Res 1988;6:1-12.

This study evaluated the effect of cryopreserva- tion on the structural organization, biosynthetic ac- tivity, and material properties of canine menisci.

The menisci were cryopreserved by incubating them in a 4% solution of dimethyl sulfoxide (DMSO) in physiologic media and freezing them to -100°C using a controlled-rate freezing system. The menisci were then stored for varying periods of time from 0 to 12 weeks in liquid nitrogen ( - 196°C). Following rapid thawing, changes in the histologic appearance and biosynthetic activity of the menisci were evaluated as functions of storage time. In ad- dition, the effects of the cryopreservation process on the tensile strength and modulus of the meniscal tissue were assessed. Although cryopreservation and short-term storage did not appear to affect the morphological appearance or biomechanical char- acter of the menisci, biosynthetic activity, as deter- mined by NA2S35SO4 incorporation, was dimin- ished to <50% of normal control values immedi- ately following cryopreservat ion and thawing. Autoradiographic examination of these tissues re- vealed that only -10% of the meniscal cells were metabolically active, however, indicating that a marked increase in the metabolic activity of indi- vidual cells occurs following the freeze-thaw cycle. Total metabolic activity continued to decline with storage time.

Viability of Ligaments after Freezing: An Experimen- tal Study in a Rabbit Model. By C. Frank, P. Ed- wards, D. McDonald, D. Bodie, and P. Sabiston. J Orthop Res 1988;6:95-102.

Our purpose in this study was to assess ligament fibroblast viability after freezing by quantifying the subsequent ability of fibroblasts to synthesize col- lagen in vitro. Both medial collateral ligament (MCL) complexes from 40 adolescent rabbits were studied. Collagen production was determined by in vitro incubation of ligaments in 3H-proline (a colla- gen precursor) and subsequent analysis of 3H- hydroxyproline (a marker of newly synthesized col- lagen). Autoradiographs determined the distribu- tions of ligament cell activity. All right MCL complexes served as fresh controls, providing a baseline of collagen production. Each left MCL was assigned to an experimental group and was either incubated fresh (10 animals), "killed" by drying, multiple freeze thawing, or cycloheximide (6 ani- mals), or slowly frozen at -70°C without cryopro- tection (24 animals). Collagen production of rapidly thawed ligaments was studied by proline incubation at 1 day, 9 days, or 6 weeks after freezing and was compared with that of contralateral fresh controls. Results demonstrate that some cells in the sub-

Arthroscopy, Vol. 4, No. 4, 1988

300 ABSTRACTS

stance of these rabbit ligaments retained the ability to synthesize collagen in vitro after being frozen for up to 6 weeks. Mean collagen production of frozen ligaments was decreased, but tests of mean and me- dian values, as well as ratios, were statistically sim- ilar to fresh contralateral ligaments in all animals. This postfreezing ligament cell survival and colla- gen production after -70°C storage may have im- plications for ligament transplantation.

Protease Inhibitors Decrease Rabbit Cartilage Degra- dation after Meniscectomy. By Claudia B. Caputo, Linda A. Sygowski, Steven P. Patton, Donald J. Wolanin, Andrew Shaw, Richard A. Roberts, and Gene DiPasquale. J Orthop Res 1988;6:103-8.

In vitro proteoglycan (PG) synthesis and release were measured on cartilage removed from rabbit knees within 1 week of meniscectomy. Three days following partial lateral meniscectomy, 72% of the femurs and 82% of the tibias had visible ulcers. Car- tilage from the weight-bearing areas incorporated 2.0-2.9 times more aSS-sulfate in vitro than cartilage from the opposite, unoperated knees. 3H-thymidine incorporation was 2.5-3.4 times higher for surgical than control groups, aSS-sulfate incorporation by the surgical group was inhibited by 22% in the pres- ence of l 0 - 4 M U24522, an inhibitor of rabbit chon- drocyte metalloprotease (CMP). 3H-thymidine in- corporation by the surgical group was inhibited by 28% by 10 - 4 M U24522. In vitro PG release from cartilage removed 2 days after surgery was 1.6-3.7 times higher for the surgical group than the control group. PG release by the surgical group after 22 h of incubation was reduced to the control level by three CMP inhibitors, U24278, U24279, and U24522. PG release by cartilage from the nonsurgical group was also reduced by these compounds at 22 h. These results suggest that both the anabolic and catabolic processes that are stimulated by surgery can be iso- lated in vitro and that CMP may be involved in the catabolic process.

Tendon Implantation into Bone: An Experimental Study. By. J. R. Jones, J. G. Smibert, C. J. McCul- lough, A. B. Price, and W. C. Hutton. J Hand Surg [Br] 1987;12:306-12.

The authors report the results of an experimental study of the mechanical properties and histological

structure of the tendon-bone junction following sur- gical implantation of tendon into bone in the rabbit. The early surgical steps were the same for tendon transfer and graft. The flexor digitorum profundus tendon of an adult Sandy Lop rabbit was divided at its insertion, the vincula brevia excised, and the cavity prepared in the distal third of the middle pha- lanx. For the tendon transfer, the dorsal cortex of the phalanx was broached with a fine Kirschner wire. A Bunnell suture of 6/0 Prolene was then placed through the dorsal cortex and secured over a dental roll on the dorsum of the digit. For the ten- don graft, a Bunnell suture was again placed in the distal tendon. Then, through a proximal plantar in- cision, the flexor digitorum profundus tendon was identified and withdrawn from the flexor tendon sheath into the proximal wound. The tendon was then rerouted through the sheath using the Bunnell suture. The tendon was divided proximal to the ten- don sheath and repaired with a Kessler suture of 6/0 Prolene. The distal end of the tendon was then se- cured to the bones as above. The animals were killed after 4, 6, 8, 12, and 20 weeks to measure the tensile strength of the tendon-bone junction. The middle phalanx, with the attached flexor digitorum profundus tendon, was dissected out and the tendon defined to its insertions. The bone was mounted in a specially designed clamp, and the proximal end of the tendon was secured by a second clamp. All specimens were mounted in the testing apparatus with an initial head separation of 8.5 mm. Prelimi- nary studies on normal tendon insertions indicated that with loading at 150 mm/min, failure of the ten- don-bone junction occurred with either avulsion of the tendon or, more rarely, an avulsion fracture. Increasing the loading rate of 300 mm/min did not increase the maximum load sustained by the ten- don-bone junction. The results following tendon transfer and tendon grafting were compared. The normal four-zone tendon junction was not repro- duced histologically in either group. After 20 weeks, the mechanical strength of the tendon trans- fers had reached 60% of the controls and that of the tendon grafts 20% of the controls. Microangiogra- phy demonstrated that these differences were not related to the vascularization of the tendon-bone junction. The mechanical properties of the tendon- bone junction may depend more on the functional state of the implanted tendon than on its structure.

Arthroscopy, Vol. 4, No. 4, 1988