Arthroscopy:

The Journal of Arthroscopic

and Related Surgery

8(4):541-543

Published by Raven Press, Ltd. 0 1992Arthroscopy Association of North America

Case Report

Recurrent Atraumatic Superior Dislocation of the Patella: Case Report and Review of the Literature David D. Teuscher and Ty H. Goletz

Summary: Recurrent atraumatic superior dislocation of the patella with spontaneous reduction prevented by interlocking osteophytes has not been previously reported. Eight previous case reports were noted in the literature with single episodes of interlocking by osteophytes in a superior dislocation, none with recurrence, and all treated by closed reduction. The presentation of a 60-year-old woman with recurrent atraumatic superior dislocation of the patella on three separate occasions required closed reduction due to interlocking patella and trochlear osteophytes that were preventing spontaneous reduction. Arthroscopic debridement of these osteophytes resulted in no functional limitation or recurrence of dislocation at 2%month follow-up. This case demonstrates successful arthroscopic treatment of this previously unreported condition. In light of the increasingly active aging population with coexistent patellofemoral joint osteoarthritis, this presentation may become more frequent. Key Words: Knee-Dislocation.

patella laterally to unlock the osteophytes, and at the subsequent second and third dislocations by closed reduction without anesthesia, using the same maneuver. Before the reduction maneuver, attempted passive flexion by gravity was prevented by the interlocked osteophytes. Because of the recurrent nature of her problem, the patient underwent arthroscopic debridement using a pituitary rongeur and abrasion burr of the trochlear and patellar osteophytes. Postoperative radiographs noted complete removal of the osteophytes (Fig. 3). She underwent a standard knee rehabilitation program without bracing and returned to activities as tolerated. At 28 months’ follow-up, she reports no locking episode since the arthroscopic procedure, and has resumed pain-free activities such as tennis, walking, and housework. Her right knee has a full stable range of motion, no effusion, with minimal patellofemoral crepitus without locking in extreme of extension with active quadriceps contraction.

CASE REPORT A 60-year-old woman presented on three separate occasions during a 9-month period, with right knee pain and inability to flex from the fully extended position after atraumatic hyperextension of the right knee while doing housework. She was able to straight leg raise, but could not flex and had an obvious deformity of the anterior portion of the knee, with the superior patellar pole prominent and a dimple inferiorly. Radiographs noted interlocking of the osteophytes on the inferior pole of the patella and the proximal trochlear groove (Figs. 1 and 2). Closed reduction with general anesthesia was accomplished at the initial presentation by moving the From the Center for Orthopaedic Surgery and Sports Medicine, San Antonio, and Brooke Army Medical Center, Ft. Sam Houston, Texas. Address correspondence and reprint requests to Dr. T. H. Goletz at 7940 Floyd Curl, Suite 560, Medical Center Tower II, San Antonio, TX 78229, U.S.A.

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D. D. TEUSCHER AND T. H. GOLETZ

FIG. 1. Lateral radiograph of dislocated patella with interlocked osteophytes.

DISCUSSION We found superior dislocation of the patella with fixation by interlocking osteophytes reported eight times in the literature, each of which was documented as a single episode (l-7). Five of these cases involved direct trauma to the anterior aspect of the knee, one attributed to the pressure of a knee restraint during reduction of a Colles’ fracture under general anesthesia (6), and the remaining four cases when the knee was struck against the bumper of a parked car, a chair, or a steel counter edge (2,3,5,7). The only reported cases of atraumatic superior dislocation with interlocking osteophytes were in patients who hyperextended their knee while stretching over the edge of a bed, car trunk, or a couch (1,497). Each of the previously reported cases noted locking of the knee in extreme extension with inability to flex, all in patients age 52 years or older. It has been postulated that the posteriorly directed force on the inferior pole of the patella in combination with quadriceps contraction of an extended knee lead to locking in the traumatic cases (1). In the atraumatic cases reported, as well as in our case, a Arthroscopy, Vol. 8, No. 4, 1992

FIG. 2. Anteroposterior tella.

radiograph of superiorly dislocated pa-

preexisting osteoarthritic knee with extreme of extension and active quadriceps contraction appeared to be the only factors leading to the fixed dislocation. No evidence of a primary patellar ligament rupture (8-12), patella alta (11,13,14), ligamentous laxity (15,16), or genu recurvatum (17,18) were present, which several authors have stated to be necessary for superior or recurrent dislocations to occur. This case is different from previously reported cases in two respects. First, this woman presented on three separate occasions with identical findings of superior patellar dislocations fixed by interlocking osteophytes, whereas none of the previous reports document any recurrent symptoms. Second, surgical correction with the use of arthroscopic debridement resulted in complete resolution of the patient’s symptoms and resumption of full vigorous activity to her premorbid level. There is some confusion in the literature as to the use of the terms vertical and superior with regard to dislocations of the patella. When described by Watson-Jones, this type of dislocation was termed vertical when the patella is superior to the femoral condyles (6). Previously, Stimson had described a

ATRAUMATIC

SUPERIOR

DISLOCATION

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OF PATELLA

used in these cases. This would be more anatomically correct, and would eliminate confusion as to differentiating a superior dislocation from an intraarticular patellar dislocation with rotation about the vertical axis. REFERENCES 1. Bartlett DH, Gilula LA, Murphy WA. Superior dislocation of the patella fixed by interlocked osteophytes: a case report and review of the literature. J Bone Joint Surg [Am] 1976;58:883-4. 2. Friden T. A case of superior dislocation of the patella. Acta Orthop Stand

1987;58:429-30.

3. Hanspal RS. Superior dislocation of the patella. Injury 1985;16:487-8. 4. Roth RM, McCabe JB. Nontraumatic superior dislocation of the patella. J Emerg Med 1985;3:265-7. 5. Siegel MG, Mac SS. Superior dislocation of the patella with interlocking osteophytes. J Trauma 1982;22:2534. 6. Watson-Jones R. Fractures and joint injuries, 2nd ed. Baltimore: Williams & Wilkins, 1941669. 7. Wimsatt MH, Carey EJ. Superior dislocation of the patella. J Trauma 1977;17:77-80.

FIG. 3. Lateral radiograph of knee after arthroscopic ment of trochlear and patellar osteophytes.

debride-

vertical dislocation as when the patella rotated on its longitudinal axis (19). Subsequent reported cases described as vertical dislocations by both DePalma and Kaufman and Hoberman noted that the dislocation was a rotation of the patella about its longitudinal axis and fixed in the intercondylar space (10,20). Larson and Jones classified the acute dislocations as one of four types: lateral, intraarticular, vertical, or intercondylar (21). They used the term intraarticular to describe cases of the patella dislocated into the intercondylar space without fracture, and the term vertical dislocation applied to cases in which the patella was pushed proximally and locked over the osteophytes of the femoral condyle. We would agree with Siegel and Mac (5) that the term superior dislocation of the patella with interlocking osteophytes, and not vertical dislocation, should be

8. Campbell WC. A text-book on orthopedic surgery. Philadelphia: WB Saunders, 1930:328. 9. Cotton FJ. Dislocations and joint-fractures. Philadelphia: WB Saunders, 1924:592. 10. DePalma A. Disease of the knee. Philadelphia: Lippincott, 1954:187-200. 11. Key JA, Conwell HE. The management offractures, dislocations and sprains. St. Louis: CV Mosby, 1934:93%9. 12. Speed K. A text-book of fractures and dislocations. Philadelphia: Lea and Febiger, 1935:795. 13. Insall J. Goldbere V. Salvati E. Recurrent dislocation and high-riding patella. Clin Orthop 1972;88:67-9. 14. Smillie IS. Injuries of the knee joint, 4th ed. Baltimore: Williams and Wilkins, 1970:245. 15. Avogaro P, Laura S, Castellani A. Ehlers-Danlos syndrome with some unusual skeletal abnormalities. C/in Orthop 1969;65: 185-90.

16. Carter C, Sweetnam R. Familial joint laxity and recurrent dislocation of the patella. J Bone Joint Surg [Br] 1958; 401664-7. 17. Freeman BL III. Recurrent dislocations. In: Crenshaw AH, ed. Campbell’s operative orthopaedics. 7th ed, vol 3. St. Louis: CV Mosby, 1987:2173. 18. Whitman R. A treatise on orthopaedic surgery. Philadelphia: Lea Brothers and Co., 1901:329. 19. Stimson LA. A practical treatise on fractures and dislocations, 3rd ed. New York: Lea Brothers and Co., 1900:793-4. 20. Kaufman I, Hoberman E. Intercondylar vertical dislocation of the patella. Bull Hosp J Dis 1973;34:222. 21. Larson RL, Jones DC. Dislocation and ligamentous injuries of the knee. In: Rockwood CA, Green DP, eds. Fractures in adults, 2nd ed, vol 2. Philadelphia: Lippincott, 1984: 1946.

Arthroscopy, Vol. 8, No. 4. 1992

Recurrent atraumatic superior dislocation of the patella: case report and review of the literature.

Recurrent atraumatic superior dislocation of the patella with spontaneous reduction prevented by interlocking osteophytes has not been previously repo...
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