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Diabetic amyotrophy is predominantly a motor condition that involves various elements of the lumbosacral plexus but particularly that related to the femoral nerve.1,3 It can present acutely as unilateral thigh pain followed by the development of weakness and later wasting in the femoral muscles, usually first seen in the quadriceps .We report on two cases of diabetic amyotrophy from different hospitals that presented with clinical signs and symptoms of quadriceps rupture. These patients underwent surgical exploration but in both the quadriceps tendons were found to be intact. Post-operative neurological consultations established the diagnosis as diabetic amyotrophy, which was confirmed with electrodiagnostic studies. We conclude that any quadriceps rupture in diabetics should be viewed with caution. Electrodiagnostic studies and imaging with ultrasound and magnetic resonance imaging should be carried out before exploratory surgery.
Keywords: quadriceps rupture, diabetes, amyotrophy
J.R.Coll.Surg.Edinb., 46, December 2001, 375-376
We describe two cases of presumed quadriceps rupture in diabetics which, on surgical exploration, were found to be intact, The cause of the pain and weakness of the quadriceps in each case was caused by the acute presentation of diabetic amyotrophy and the palpable clinical gap was in fact due to the wasted quadriceps above the patella.
Case 1
A sixty five-year-old insulin-dependent diabetic male presented with a history of a fall down the stairs one day previously and a painful lower thigh. On examination he had a palpable gap in the suprapatellar region with some mild quadriceps wasting and no active extension at the knee. There was no evidence of a peripheral diabetic neuropathy.
A clinical diagnosis of quadriceps rupture was made; further imaging was not thought to be necessary due to the clinical findings. At operation, the extensor mechanism was found to be intact. Neurophysiological investigations subsequently established the cause as diabetic amyotrophy.
Case 2
An eighty four-year-old non-insulin-dependent diabetic male presented with a history of a fall from his loft two months previously. Since the fall he had experienced pain around his lower right thigh and the leg giving way underneath him.
On examination he had marked quadriceps wasting with a palpable gap in the suprapatellar region and no active knee extension. There was also evidence of a mild glove and stocking peripheral neuropathy, characteristic of diabetes mellitus. Clinically, the diagnosis of a late presentation of quadriceps tendon rupture was made. Given the clinical features it was decided to explore the tendon, which was found to be intact. Post-operatively, neurophysiological studies were obtained and the diagnosis of diabetic amyotrophy was made. These electrodiagnostic studies revealed changes consistent with a background diabetic neuropathy and an additional right-sided diabetic amyotrophy.
Diabetic amyotrophy is a rare complication of diabetes with a reported prevalence of 0.8% in diabetic patients.1 It is a well-recognised entity distinct from other forms of diabetic neuropathy and involves various elements of the lumbosacral plexus but, particularly, that related to the femoral nerve.2 It consists of unilateral or asymmetric bilateral proximal lower limb weakness, often of subacute or more rarely acute onset, and accompanied by pain. Sensory involvement is usually minimal although a concomitant distal sensorimotor polyneuoropathy may be present. 3 Muscle involvement is usually first noted clinically in the quadriceps femoris but progresses to adjacent muscle groups over the ensuing months to one year. The natural course of diabetic amyotrophy is variable with gradual but often incomplete improvement.2 The best clue to the diagnosis is that the pain precedes the weakness. In the two cases described, the involvement of the quadriceps muscle, its acute onset, the association with traumatic episodes and the fact that diabetes mellitus predisposes the individual to quadriceps tendon rupture led to the clinical diagnosis of quadriceps rupture and unnecessary surgical exploration. We would recommend that any suspected quadriceps rupture in diabetics should be viewed with caution. The diagnosis should be confirmed with ultrasound or magnetic resonance imaging. Electrodiagnostic studies are indicated to rule out diabetic amyotrophy. Only then should exploration be carried out.
REFERENCES
1. O’ Hare JA, Abuaisha F, Geoghegan M Prevalence And Forms Of Neuropathic Morbidity In 800 Diabetics. Ir J
Med Sci 1994; 163: 132-5
2. Sander HW and Chokroverty S Diabetic Amyotrophy: Current Concepts. Seminars in Neurology. 1996;Vol 16:
No 2.
3. Thomas PK Classification, Differential Diagnosis and
Staging of Diabetic Peripheral Neuropathy. Diabetes,
1997; Vol 46: Suppl 2.
4. Rockwood CA, Green DP and Bucholz RW. Rockwood
and Green’s Fractures in Adults . Third edition 1991; Vol
2: 1816-1820.
5. Bhole R, Johnson JC Bilateral simultaneous spontaneous
rupture of quadriceps tendon in a diabetic patient. South
Med J 1985: 78(4); 486
Copyright date: 9th September 2001
Correspondence: A. Rogers, Orthopaedic Department, Morriston
Hospital, Morriston, Swansea, SA6 6NL
E-mail: scaphoid@pgen.net
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