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Congenital dislocation of the patella — the genetics and conservative management
The Knee 5 Ž1998. 235]237
Congenital dislocation of the patella } the genetics and conservative management A.H.N. RobinsonU , A. Aladin, A.J. Green, D.J. Dandy Departments of Orthopaedic Surgery and Clinical Genetics, Addenbrooke’s Hospital, Box 37, Hills Road, Cambridge CB2 2QQ, UK Accepted 12 October 1997
Abstract A 13-year-old boy presented to the orthopaedic clinic with bilateral congenital dislocation of the patella. One knee had been unsuccessfully treated elsewhere by soft tissue realignment. Following this, conservative management has given a satisfactory functional outcome, despite persistence of the dislocation. Two other family members have been reviewed, the patient’s father and grandmother. Both have bilateral patellar dislocations and neither has sought or required medical treatment. Both have functioned well and have been employed. We conclude that congenital dislocation of the patella can give good results if left untreated. It has an autosomal dominant pattern of inheritance. Q 1998 Elsevier Science B.V. All rights reserved. Keywords: Congenital dislocation; Patella; Conservative treatment; Autosomal dominant
1. Introduction Congenital dislocation of the patella is a rare condition in which the patella lies permanently dislocated on the lateral aspect of the femur. The dislocation cannot be reduced by closed manipulation and is said to cause progressive symptoms until walking is impossible if both knees are affected w1x. The condition is reported to be hereditary w2x. Most reports concentrate on the surgical treatment of this condition, with various procedures described to realign the patella w1,3x. 2. Patients A 13-year-old boy presented to the casualty depart-
U
Corresponding author. Tel.: q44 1223 245151.
0968-0160r98r$19.00 Q 1998 Elsevier Science B.V. All rights reserved. PII S0968-0160Ž97.10022-9
ment of another hospital in 1986. He had banged his knee climbing out of a swimming pool. Examination revealed him to have an irreducible laterally dislocated left patella. He was also noted to have the same deformity on the opposite leg. Coexisting deformities of genu valgus, external tibial torsion and pes cavus were also noted. The diagnosis of bilateral congenital dislocation of the patellae was made. Conn’s procedure w3x was performed on the left knee, but failed to stabilise the patella. Following this conservative treatment of both knees was advised. A review of the patient at 23 years of age ŽFigs. 1 and 2. has shown him to have adequate knee function. He works in a manual job, can walk unlimited distances, occasionally limps and has intermittent slight pain on descending stairs. Sitting does not cause pain. He does not take part in sport. The extensor mechanism is weak and he is unable to stand from a squatting position without using his hands to aid him.
236
A.H.N. Robinson et al. r The Knee 5 (1998) 235]237
Fig. 1. Photograph of the knees of the index case with the patellae outlined in ink. Note scars of previous surgery on the right.
His main complaint is of limited flexion of his operated knee. He has full extension of each knee Žrange of movement: Ž2r0r135... Questioning the family revealed a strong family history of knee problems ŽFig. 3.. The patient’s father and paternal grandmother have also been examined and have bilateral, irreducible patella dislocation of long standing. None of the patients examined had
abnormal nails, elbow deformity or evidence of iliac horns. Similarly there were no features of familial joint laxity. Many other members of the family have undergone knee surgery in the past, although it has not been possible to trace them. The patient’s father is 45 years old and has a bilaterally dislocated patellae. He is active and occasionally plays badminton. He has no pain on descending stairs, never limps and says that his knee function has not deteriorated with the passage of time. He also requires help to stand from squatting, but has a full range of knee movement Ž2r0r135.. The patient’s grandmother is 78. She suffers occasional anterior knee pain after walking long distances and on descending stairs but can sit for unlimited periods. She has a full range of knee movement Ž0r0r125., remaining active with a lifestyle that is not restricted by her knees. 3. Discussion In this report we have documented the familial nature of congenital dislocation of the patella. Such a
Fig. 2. Radiographs of the right knee: in the lateral Ža. the patella is outlined for better visualisation. The skyline view Žb. shows poor development of both the patella and the trochlea groove. The radiographs of the left are the mirror image.
A.H.N. Robinson et al. r The Knee 5 (1998) 235]237
237
Fig. 3. ŽTABLE. Genealogical table of the reported family. The arrow indicates the index case.
familial pattern has been reported before by Mumford w2x, who only saw the index case and relied on the history for the others. Green and Waugh w4x reported an association between a 76-year-old lady who may have had congenital dislocation of the patella and relatives with small and recurrently dislocating patellae. The fact that the patellae were reducible excludes a diagnosis of congenital dislocation. The condition described differs from the ‘small patella’ syndrome described by Scott and Taor w5x. The patients did not have evidence of the pelvic, foot or ankle abnormalities associated with this condition. The patients’ patellae were of a normal size and were permanently dislocated in all cases, which differentiates our patients from those with the small patella syndrome w6x. Similarly they did not have the features of ‘nail-patella’ syndrome. Transmission of congenital dislocation of the patella from father to son implies that in this family the condition is an autosomal dominant. This is the same pattern of inheritance as recurrent patellar dislocation and the small patella syndrome. Previous reports have concentrated on surgical methods of correcting the dislocation. The only case in the English literature of conservative treatment was the 76-year-old lady documented by Green and Waugh w4x who had good function despite a 308 fixed flexion deformity. Our cases reveal good clinical function, with minimal symptoms from our youngest patient of 23 years to our oldest of 78 years. Anterior knee pain was not a problem. There was definite weakness of the extensor mechanism with trick move-
ments using the hands needed to rise from squatting and sitting, but this does not seem to concern these patients, perhaps because they have always been so disabled. It is well documented that realignment procedures performed in the first 2 decades give good results with restoration of extensor power w1,7x. However, the natural history of the condition has not been previously well documented and our three patients have only minimal symptoms from their dislocated patellae. In conclusion it may well be acceptable to leave the patella dislocated in older patients diagnosed after the first decade, but they should be advised that weakness of knee extension will persist. References w1x Stanisavljevic S, Zemenick G, Miller D. Congenital, irreducible, permanent lateral dislocation of the patella. Clin Orthop 1975;116:190]199. w2x Mumford EB. Congenital dislocation of the patella: case report with history of four generations. J Bone Jt Surg 1947;29:1083]1086. w3x Conn HR. A new method of operative reduction for congenital luxation of the patella. J Bone Jt Surg 1924;7:370]381. w4x Green JP, Waugh W. Congenital lateral dislocation of the patella. J Bone Jt Surg ŽBr. 1968;50-B:285]289. w5x Scott JE, Taor WS. The small patella syndrome. J Bone Jt Surg wBrx 1979;61 B:172]175. w6x Dellestable F, Pere P, Blum A, Regent D, Gaucher A. The small patella syndrome. J Bone Jt Surg wBrx 1996;78-B:63]65. w7x Jones RDS, Fisher RL, Curtis BH. Congenital dislocation of the patella. Clin Orthop 1975;119:177]183.
Congenital dislocation of the patella } the genetics and conservative management A.H.N. RobinsonU , A. Aladin, A.J. Green, D.J. Dandy Departments of Orthopaedic Surgery and Clinical Genetics, Addenbrooke’s Hospital, Box 37, Hills Road, Cambridge CB2 2QQ, UK Accepted 12 October 1997
Abstract A 13-year-old boy presented to the orthopaedic clinic with bilateral congenital dislocation of the patella. One knee had been unsuccessfully treated elsewhere by soft tissue realignment. Following this, conservative management has given a satisfactory functional outcome, despite persistence of the dislocation. Two other family members have been reviewed, the patient’s father and grandmother. Both have bilateral patellar dislocations and neither has sought or required medical treatment. Both have functioned well and have been employed. We conclude that congenital dislocation of the patella can give good results if left untreated. It has an autosomal dominant pattern of inheritance. Q 1998 Elsevier Science B.V. All rights reserved. Keywords: Congenital dislocation; Patella; Conservative treatment; Autosomal dominant
1. Introduction Congenital dislocation of the patella is a rare condition in which the patella lies permanently dislocated on the lateral aspect of the femur. The dislocation cannot be reduced by closed manipulation and is said to cause progressive symptoms until walking is impossible if both knees are affected w1x. The condition is reported to be hereditary w2x. Most reports concentrate on the surgical treatment of this condition, with various procedures described to realign the patella w1,3x. 2. Patients A 13-year-old boy presented to the casualty depart-
U
Corresponding author. Tel.: q44 1223 245151.
0968-0160r98r$19.00 Q 1998 Elsevier Science B.V. All rights reserved. PII S0968-0160Ž97.10022-9
ment of another hospital in 1986. He had banged his knee climbing out of a swimming pool. Examination revealed him to have an irreducible laterally dislocated left patella. He was also noted to have the same deformity on the opposite leg. Coexisting deformities of genu valgus, external tibial torsion and pes cavus were also noted. The diagnosis of bilateral congenital dislocation of the patellae was made. Conn’s procedure w3x was performed on the left knee, but failed to stabilise the patella. Following this conservative treatment of both knees was advised. A review of the patient at 23 years of age ŽFigs. 1 and 2. has shown him to have adequate knee function. He works in a manual job, can walk unlimited distances, occasionally limps and has intermittent slight pain on descending stairs. Sitting does not cause pain. He does not take part in sport. The extensor mechanism is weak and he is unable to stand from a squatting position without using his hands to aid him.
236
A.H.N. Robinson et al. r The Knee 5 (1998) 235]237
Fig. 1. Photograph of the knees of the index case with the patellae outlined in ink. Note scars of previous surgery on the right.
His main complaint is of limited flexion of his operated knee. He has full extension of each knee Žrange of movement: Ž2r0r135... Questioning the family revealed a strong family history of knee problems ŽFig. 3.. The patient’s father and paternal grandmother have also been examined and have bilateral, irreducible patella dislocation of long standing. None of the patients examined had
abnormal nails, elbow deformity or evidence of iliac horns. Similarly there were no features of familial joint laxity. Many other members of the family have undergone knee surgery in the past, although it has not been possible to trace them. The patient’s father is 45 years old and has a bilaterally dislocated patellae. He is active and occasionally plays badminton. He has no pain on descending stairs, never limps and says that his knee function has not deteriorated with the passage of time. He also requires help to stand from squatting, but has a full range of knee movement Ž2r0r135.. The patient’s grandmother is 78. She suffers occasional anterior knee pain after walking long distances and on descending stairs but can sit for unlimited periods. She has a full range of knee movement Ž0r0r125., remaining active with a lifestyle that is not restricted by her knees. 3. Discussion In this report we have documented the familial nature of congenital dislocation of the patella. Such a
Fig. 2. Radiographs of the right knee: in the lateral Ža. the patella is outlined for better visualisation. The skyline view Žb. shows poor development of both the patella and the trochlea groove. The radiographs of the left are the mirror image.
A.H.N. Robinson et al. r The Knee 5 (1998) 235]237
237
Fig. 3. ŽTABLE. Genealogical table of the reported family. The arrow indicates the index case.
familial pattern has been reported before by Mumford w2x, who only saw the index case and relied on the history for the others. Green and Waugh w4x reported an association between a 76-year-old lady who may have had congenital dislocation of the patella and relatives with small and recurrently dislocating patellae. The fact that the patellae were reducible excludes a diagnosis of congenital dislocation. The condition described differs from the ‘small patella’ syndrome described by Scott and Taor w5x. The patients did not have evidence of the pelvic, foot or ankle abnormalities associated with this condition. The patients’ patellae were of a normal size and were permanently dislocated in all cases, which differentiates our patients from those with the small patella syndrome w6x. Similarly they did not have the features of ‘nail-patella’ syndrome. Transmission of congenital dislocation of the patella from father to son implies that in this family the condition is an autosomal dominant. This is the same pattern of inheritance as recurrent patellar dislocation and the small patella syndrome. Previous reports have concentrated on surgical methods of correcting the dislocation. The only case in the English literature of conservative treatment was the 76-year-old lady documented by Green and Waugh w4x who had good function despite a 308 fixed flexion deformity. Our cases reveal good clinical function, with minimal symptoms from our youngest patient of 23 years to our oldest of 78 years. Anterior knee pain was not a problem. There was definite weakness of the extensor mechanism with trick move-
ments using the hands needed to rise from squatting and sitting, but this does not seem to concern these patients, perhaps because they have always been so disabled. It is well documented that realignment procedures performed in the first 2 decades give good results with restoration of extensor power w1,7x. However, the natural history of the condition has not been previously well documented and our three patients have only minimal symptoms from their dislocated patellae. In conclusion it may well be acceptable to leave the patella dislocated in older patients diagnosed after the first decade, but they should be advised that weakness of knee extension will persist. References w1x Stanisavljevic S, Zemenick G, Miller D. Congenital, irreducible, permanent lateral dislocation of the patella. Clin Orthop 1975;116:190]199. w2x Mumford EB. Congenital dislocation of the patella: case report with history of four generations. J Bone Jt Surg 1947;29:1083]1086. w3x Conn HR. A new method of operative reduction for congenital luxation of the patella. J Bone Jt Surg 1924;7:370]381. w4x Green JP, Waugh W. Congenital lateral dislocation of the patella. J Bone Jt Surg ŽBr. 1968;50-B:285]289. w5x Scott JE, Taor WS. The small patella syndrome. J Bone Jt Surg wBrx 1979;61 B:172]175. w6x Dellestable F, Pere P, Blum A, Regent D, Gaucher A. The small patella syndrome. J Bone Jt Surg wBrx 1996;78-B:63]65. w7x Jones RDS, Fisher RL, Curtis BH. Congenital dislocation of the patella. Clin Orthop 1975;119:177]183.