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Ulnar nerve entrapment
LETTERS TO THE EDITOR Ulnar nerve entrapment
To the Editor: I read with interest the article "Ulnar Nerve Entrapment Due to Heterotopic Bone Formation After a Severe Bum" (J HAND SURG 1987;12A:378-80)by Vorenkamp and Nelson' in which thcy describe a case of ulnar nerve entrapment from heterotopic bone formation about the elbow joint in a bum patient. The description of the operative appearance of the nerve after release seems to be in keeping with a compressive lesion; however, it is unfortunate that specific nerve conduction studies could not be done preoperatively to objectively show isolated slowing at this level. I 'recently treated a patient with 70 degree body surface area bums in whom heterotopic calcification about both elbows, shoulders, and knees developed and who also had findings of ulnar nerve entrapment about the left elbow, with a positive Tincl's sign at this level. Nerve conduction studies showed a diffuse neuropathy with mild slowing of sensory conduction at the left elbow. This patient had a similar release and transposition subcutaneously and has begun to show signs of clinical recovery 17 months after his surgery. Cases of ulnar nerve compression from heterotopic ossification have been previously reported by Drs. Hoffer, Brody, and Fcrlic' in the Journal of Trauma in 1978. They report three patients with ulnar nerve lesions who had operative resection of heterotopic bone and ulnar nerve decompression with resolution of ulnar nerve symptoms in two patients. . Heterotopic ossification in bum and other trauma patients is still a poorly understood entity and hopefully a better understanding of its pathophysiology may help prevent the crippling joint problems it causes, as well as such isolated nerve entrapment syndromes. Michael J. Halls, MD, FRCS(C) 1327 Tourmaline St. San Diego, CA 92109
REFERENCES I. Vorcnkamp SE, Nelson TL. Ulnar nerve entrapment due to heterotopic bone formation after a severe burn. J HA I'D SURG 1987;12A:378-80. 2. Hoffer MM, Brody G, Ferlie Fred. Excision of heterotopic ossification about elbows in patients with thermal injury. J Trauma 1978;18:667-70.
Reply Thank you for your commentary on our article concerning ulnar nerve entrapment from heterotopic bone formation about the elbow joint in a bum patient. We
would have liked to have the opportunity to perform preoperative nerve conduction studies, but at the time this was not possible because of the patient's nerve function and the relative unavailability of EMG's on short notice in our hospital. Dr. Hoffer's paper does address problems similar to those we reported. We would hope in the future to review a larger number of similar cases and attempt to understand this entity and formulate an effective treatment plan. Terry L. Nelson, M.D. 150 E. Crosstown Center Kalamazoo, AU 49001
Scaphoid screws
To the Editor: The treatment of the fractured scaphoid still imposes a great challenge to the hand surgeon. Recent advances in this area include new designs of compression screws and the use of electrical stimulation by invasive, semiinvasive, or noninvasive systems.' In the article "A Biomechanical Comparison of Scaphoid Screws" by James A. Shaw (J HAND SURG 1987;12A:347-53) commonly available screws were tested by comparison of their fixation capability and size compatability. These factors are undoubtedly important in achieving an anatomical reduction that will improve both healing and future function of the carpal bones .
Logically, better (biological) size compatability is beneficial in achieving these purposes. It is not so clear regarding fixation capacity. "Appropriate" compression force is the one that is favorable for bone healing, it does not necessarily mean the strongest one. In fact, excessive force can disturb bone healing by leading to additional unnecessary damage to the cells at the fracture site and to unfavorable changes of the electrical currents generated at this site. Such changes may impair the formation of callus and the osteogenesis that are influenced by the electrical environment.2,J Therefore, while one can agree with the results achieved in Dr. Shaw's experiment, the conclusions derived from the degree of fixat ion capacity for each screw are not essentially correct. This experiment provides no data on the favorable compression force for the healing of the fractured scaphoid. This ideal force is still left to be determined. As the best is sometimes the enemy of the good, better fixation capacity dose not essentially means better healing. The results achieved with the Herbert screw seem
TIlE JOURNALOF llANO SURGERY
461
To the Editor: I read with interest the article "Ulnar Nerve Entrapment Due to Heterotopic Bone Formation After a Severe Bum" (J HAND SURG 1987;12A:378-80)by Vorenkamp and Nelson' in which thcy describe a case of ulnar nerve entrapment from heterotopic bone formation about the elbow joint in a bum patient. The description of the operative appearance of the nerve after release seems to be in keeping with a compressive lesion; however, it is unfortunate that specific nerve conduction studies could not be done preoperatively to objectively show isolated slowing at this level. I 'recently treated a patient with 70 degree body surface area bums in whom heterotopic calcification about both elbows, shoulders, and knees developed and who also had findings of ulnar nerve entrapment about the left elbow, with a positive Tincl's sign at this level. Nerve conduction studies showed a diffuse neuropathy with mild slowing of sensory conduction at the left elbow. This patient had a similar release and transposition subcutaneously and has begun to show signs of clinical recovery 17 months after his surgery. Cases of ulnar nerve compression from heterotopic ossification have been previously reported by Drs. Hoffer, Brody, and Fcrlic' in the Journal of Trauma in 1978. They report three patients with ulnar nerve lesions who had operative resection of heterotopic bone and ulnar nerve decompression with resolution of ulnar nerve symptoms in two patients. . Heterotopic ossification in bum and other trauma patients is still a poorly understood entity and hopefully a better understanding of its pathophysiology may help prevent the crippling joint problems it causes, as well as such isolated nerve entrapment syndromes. Michael J. Halls, MD, FRCS(C) 1327 Tourmaline St. San Diego, CA 92109
REFERENCES I. Vorcnkamp SE, Nelson TL. Ulnar nerve entrapment due to heterotopic bone formation after a severe burn. J HA I'D SURG 1987;12A:378-80. 2. Hoffer MM, Brody G, Ferlie Fred. Excision of heterotopic ossification about elbows in patients with thermal injury. J Trauma 1978;18:667-70.
Reply Thank you for your commentary on our article concerning ulnar nerve entrapment from heterotopic bone formation about the elbow joint in a bum patient. We
would have liked to have the opportunity to perform preoperative nerve conduction studies, but at the time this was not possible because of the patient's nerve function and the relative unavailability of EMG's on short notice in our hospital. Dr. Hoffer's paper does address problems similar to those we reported. We would hope in the future to review a larger number of similar cases and attempt to understand this entity and formulate an effective treatment plan. Terry L. Nelson, M.D. 150 E. Crosstown Center Kalamazoo, AU 49001
Scaphoid screws
To the Editor: The treatment of the fractured scaphoid still imposes a great challenge to the hand surgeon. Recent advances in this area include new designs of compression screws and the use of electrical stimulation by invasive, semiinvasive, or noninvasive systems.' In the article "A Biomechanical Comparison of Scaphoid Screws" by James A. Shaw (J HAND SURG 1987;12A:347-53) commonly available screws were tested by comparison of their fixation capability and size compatability. These factors are undoubtedly important in achieving an anatomical reduction that will improve both healing and future function of the carpal bones .
Logically, better (biological) size compatability is beneficial in achieving these purposes. It is not so clear regarding fixation capacity. "Appropriate" compression force is the one that is favorable for bone healing, it does not necessarily mean the strongest one. In fact, excessive force can disturb bone healing by leading to additional unnecessary damage to the cells at the fracture site and to unfavorable changes of the electrical currents generated at this site. Such changes may impair the formation of callus and the osteogenesis that are influenced by the electrical environment.2,J Therefore, while one can agree with the results achieved in Dr. Shaw's experiment, the conclusions derived from the degree of fixat ion capacity for each screw are not essentially correct. This experiment provides no data on the favorable compression force for the healing of the fractured scaphoid. This ideal force is still left to be determined. As the best is sometimes the enemy of the good, better fixation capacity dose not essentially means better healing. The results achieved with the Herbert screw seem
TIlE JOURNALOF llANO SURGERY
461