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Nontraumatic superior dislocation of the patella
The Journal
of Emergency
Medune.
Vol 3. pp 265-267.
1985
PrInted In the USA . Copyright
15 1965 Pergamon
Press Ltd
NONTRAUMATtC SUPERIOR DlSlOCATlON OF THE PATELLA Robert M. Roth,
Reprint
DO*,
and John 8.
M&&b%
MD,
FACEPt
‘Resident Instructor, Department of Emergency Medicine, TAssociate Professor, Department of Emergency Medclne, Wright State Unwersity, School of Medicine, Dayton. Ohio address. John B. McCabe MD, P.O. Box 927, Dayton, OH 45401
0 AMA caseof superior pat&r dition is described. Tbe dislocation was sustained without apparent trauma. Closed reduction was nccomplislsed in the emergency department. No apprrent injury to the patelhr ligament WPS sustained. 0 Keywords - patells; dislocation
introduction
Pat&u dislocationis a common problem seenby the emergencyphysician.Although lateraldislocationof the patellais the most commonform of patellardislocation,’other types of dislocations have also been described. We describea caseof nontraumatic superior dislocation of the patella without ruptureof the patellartendon.We reportthis caseto bring to the attention of emergencyphysiciansthe variety of possibledislocationsof thepatellaandto demonstrate the easewith which this particular dislocation was treated in the emergency department. Caee Report
mobile. Upon standingupright again, he wasunableto flex the knee.At that point, he experiencedpain in the left knee and noted that the “knee cap was stuck above his knee.” Physical examinationin the emergency departmentshowedno evidenceof trauma to the knee.Therewasno effusion.A highriding nonmobilepatellawasnoted.There was no pain on palpation of the knee.No gap was palpableover the areaof the patellar ligament. Radiographicexaminationof the knee revealeda superiorlydisplacedleft patella (Figs l-3). No fractureswerenoted. The patientwasgivenmeperidine75 mg and promethazine50mg intramuscularly. The patellardislocationwasreducedin the following manner:The kneewashyperextended.The patellawasgraspedand lifted anteriorly.Thepatellawasmovedinferiorly. Following reduction,full rangeof motion of the knee was possible. The kneewasimmobilized, and the patient sent home with instructions for ten daysof nonweightbearing.In follow-up,resultsof the kneeexaminationwerenormal.
A 52-year-oldman was seenin the emergencydepartmentwith a complaint of “his kneebeingstuck.” The patient had hyperextendedhis left kneewhile placinga heavy metal object into the trunk of his auto-
Discussion
Patellar dislocationscan be divided into two major categories.2Extra-art&Jar dislocationoccurswhenthe patdla liesoutside
Clinical Communications, focusing primarily on adult emergencies, is coordinated by Michael Tomlanovich, MD,of HenryFord Hospital in Detroit. RECEIVED: 26 March 1985;ACCEPTED: 9 May 1985 0736-4679/85 $3.00 + .OO 265
266
Robert
Figure 3. Dmwktg to iltustmte podtioll of the dhlowtioll.
Figure 1. A-P mdiogmph showing placement of the pstelh.
Figure 2. Lateral radiograph displacement of the patella.
superior
showing
dls-
superior
M. Roth
the high-fldlng
the space anterior to the femoral condyles. This occurs most commonly in the lateral direction, but may also occur in the superior or medial direction. Intra-articular dislocation occurs when the patella rotates on its horizontal or vertical axis but remains between the femoral condyles. This terminology is somewhat confusing, but becomes clear when one considers that it is the patello-femoral joint and not the femoraltibial joint that is used as the reference joint in naming the type of dislocation. Intraarticular dislocations can be horizontal or intercondylar, depending on the axis of rotation of the patella.3,4 Our case is one of superior dislocation of the patella, an extra-articular dislocation. This is an uncommon injury, with only five reported cases in the English literature.2.s-7 Two mechanisms of injury appear responsible for this dislocation.6 In traumatic injury, a direct force to the inferior pole of the patella may displace the patella superiorly. If osteophytes are present on the patella or distal femur, these may lock and prevent return of the patella to its normal anatomic position. In the absence of trauma, it is presumed that forceful contraction
Patellar
267
Dlslocatm
of the quadriceps, especially with laxity of the patellar ligament, may allow for superior displacement of the patella. Again, a patella displaced in this manner may become locked in the dislocated position. The first report of superior dislocation of the patella was by Watson-Jones5 in a 67-year-old man. The dislocation was reduced under general anesthesia, with fracture of one of the interlocked osteophytes. In 1977 Wimsatt and Carey2 reported two cases of superior dislocation. Both were hyperextension-type injuries, one being associated with trauma. Both patients had closed reduction performed, and neither patient experienced a patellar ligament rupture. Siegel and Mac’ reported a single case of nontraumatic superior dislocation treated with closed reduction. Again, no residual
injury was noted following reduction of the dislocation. Several authors have suggested that superior dislocation of the patella can only exist with primary patellar ligament rupture.‘,’ This was not true in our case, or other cases reported in the literature. Our patient was able to fully extend the knee after reduction. Superior dislocation of the patella is a rare injury and may occur without significant trauma. All cases reported in the literature to date have occurred with an intact patellar ligament. All but the original case described by Watson-Jones have been easily reduced without the need for general anesthetic. It is important for the emergency physician to be able to both recognize and treat this unusual dislocation.
REFERENCES 1. DePalma AF: The Management of Fractures and Dislocations. 2d ed, Philadelphia, WB Saunders, 1970. 2. Wimsatt MH, Carey EJ: Superior dislocation of the patella. J Trauma 1977; 17~77-79. 3. Brady TA, Russell D: Interarticular horizontal dislocation of the patella: A case report. J Bone Joint Surg 1%5; 47-A:1393-13%. 4. Garrison RT, McCabe JB: An unusual case of intraarticular dislocation of the patella. Ann Emerg Med 1984; 13:108-110. 5. Watson-Jones R: Fractures and Joint Injury, 3d ed,
~012, Baltimore, Williams & Wilkins, 1943, p 908. 6. Bartlett DH, Gilula LA, Murphy WA: Superior dislocation of the patella affixed by interlocked osteophytes. J Bone Joint Surg 1976; 58A:883-884. 7. Siegel MG, Mac SS: Superior dislocation of the patella with interlocking osteophytes. J Trauma 1982; 22:253-254. 8. Campbell WC: A Textbook on Orthopedic Surgery. Philadelphia, WB Saunders, 1930, p 328. 9. DePalma A: Diseases of the Knee, Philadelphia, Lippincott, 1954, p 200.
of Emergency
Medune.
Vol 3. pp 265-267.
1985
PrInted In the USA . Copyright
15 1965 Pergamon
Press Ltd
NONTRAUMATtC SUPERIOR DlSlOCATlON OF THE PATELLA Robert M. Roth,
Reprint
DO*,
and John 8.
M&&b%
MD,
FACEPt
‘Resident Instructor, Department of Emergency Medicine, TAssociate Professor, Department of Emergency Medclne, Wright State Unwersity, School of Medicine, Dayton. Ohio address. John B. McCabe MD, P.O. Box 927, Dayton, OH 45401
0 AMA caseof superior pat&r dition is described. Tbe dislocation was sustained without apparent trauma. Closed reduction was nccomplislsed in the emergency department. No apprrent injury to the patelhr ligament WPS sustained. 0 Keywords - patells; dislocation
introduction
Pat&u dislocationis a common problem seenby the emergencyphysician.Although lateraldislocationof the patellais the most commonform of patellardislocation,’other types of dislocations have also been described. We describea caseof nontraumatic superior dislocation of the patella without ruptureof the patellartendon.We reportthis caseto bring to the attention of emergencyphysiciansthe variety of possibledislocationsof thepatellaandto demonstrate the easewith which this particular dislocation was treated in the emergency department. Caee Report
mobile. Upon standingupright again, he wasunableto flex the knee.At that point, he experiencedpain in the left knee and noted that the “knee cap was stuck above his knee.” Physical examinationin the emergency departmentshowedno evidenceof trauma to the knee.Therewasno effusion.A highriding nonmobilepatellawasnoted.There was no pain on palpation of the knee.No gap was palpableover the areaof the patellar ligament. Radiographicexaminationof the knee revealeda superiorlydisplacedleft patella (Figs l-3). No fractureswerenoted. The patientwasgivenmeperidine75 mg and promethazine50mg intramuscularly. The patellardislocationwasreducedin the following manner:The kneewashyperextended.The patellawasgraspedand lifted anteriorly.Thepatellawasmovedinferiorly. Following reduction,full rangeof motion of the knee was possible. The kneewasimmobilized, and the patient sent home with instructions for ten daysof nonweightbearing.In follow-up,resultsof the kneeexaminationwerenormal.
A 52-year-oldman was seenin the emergencydepartmentwith a complaint of “his kneebeingstuck.” The patient had hyperextendedhis left kneewhile placinga heavy metal object into the trunk of his auto-
Discussion
Patellar dislocationscan be divided into two major categories.2Extra-art&Jar dislocationoccurswhenthe patdla liesoutside
Clinical Communications, focusing primarily on adult emergencies, is coordinated by Michael Tomlanovich, MD,of HenryFord Hospital in Detroit. RECEIVED: 26 March 1985;ACCEPTED: 9 May 1985 0736-4679/85 $3.00 + .OO 265
266
Robert
Figure 3. Dmwktg to iltustmte podtioll of the dhlowtioll.
Figure 1. A-P mdiogmph showing placement of the pstelh.
Figure 2. Lateral radiograph displacement of the patella.
superior
showing
dls-
superior
M. Roth
the high-fldlng
the space anterior to the femoral condyles. This occurs most commonly in the lateral direction, but may also occur in the superior or medial direction. Intra-articular dislocation occurs when the patella rotates on its horizontal or vertical axis but remains between the femoral condyles. This terminology is somewhat confusing, but becomes clear when one considers that it is the patello-femoral joint and not the femoraltibial joint that is used as the reference joint in naming the type of dislocation. Intraarticular dislocations can be horizontal or intercondylar, depending on the axis of rotation of the patella.3,4 Our case is one of superior dislocation of the patella, an extra-articular dislocation. This is an uncommon injury, with only five reported cases in the English literature.2.s-7 Two mechanisms of injury appear responsible for this dislocation.6 In traumatic injury, a direct force to the inferior pole of the patella may displace the patella superiorly. If osteophytes are present on the patella or distal femur, these may lock and prevent return of the patella to its normal anatomic position. In the absence of trauma, it is presumed that forceful contraction
Patellar
267
Dlslocatm
of the quadriceps, especially with laxity of the patellar ligament, may allow for superior displacement of the patella. Again, a patella displaced in this manner may become locked in the dislocated position. The first report of superior dislocation of the patella was by Watson-Jones5 in a 67-year-old man. The dislocation was reduced under general anesthesia, with fracture of one of the interlocked osteophytes. In 1977 Wimsatt and Carey2 reported two cases of superior dislocation. Both were hyperextension-type injuries, one being associated with trauma. Both patients had closed reduction performed, and neither patient experienced a patellar ligament rupture. Siegel and Mac’ reported a single case of nontraumatic superior dislocation treated with closed reduction. Again, no residual
injury was noted following reduction of the dislocation. Several authors have suggested that superior dislocation of the patella can only exist with primary patellar ligament rupture.‘,’ This was not true in our case, or other cases reported in the literature. Our patient was able to fully extend the knee after reduction. Superior dislocation of the patella is a rare injury and may occur without significant trauma. All cases reported in the literature to date have occurred with an intact patellar ligament. All but the original case described by Watson-Jones have been easily reduced without the need for general anesthetic. It is important for the emergency physician to be able to both recognize and treat this unusual dislocation.
REFERENCES 1. DePalma AF: The Management of Fractures and Dislocations. 2d ed, Philadelphia, WB Saunders, 1970. 2. Wimsatt MH, Carey EJ: Superior dislocation of the patella. J Trauma 1977; 17~77-79. 3. Brady TA, Russell D: Interarticular horizontal dislocation of the patella: A case report. J Bone Joint Surg 1%5; 47-A:1393-13%. 4. Garrison RT, McCabe JB: An unusual case of intraarticular dislocation of the patella. Ann Emerg Med 1984; 13:108-110. 5. Watson-Jones R: Fractures and Joint Injury, 3d ed,
~012, Baltimore, Williams & Wilkins, 1943, p 908. 6. Bartlett DH, Gilula LA, Murphy WA: Superior dislocation of the patella affixed by interlocked osteophytes. J Bone Joint Surg 1976; 58A:883-884. 7. Siegel MG, Mac SS: Superior dislocation of the patella with interlocking osteophytes. J Trauma 1982; 22:253-254. 8. Campbell WC: A Textbook on Orthopedic Surgery. Philadelphia, WB Saunders, 1930, p 328. 9. DePalma A: Diseases of the Knee, Philadelphia, Lippincott, 1954, p 200.