Hypoplasia of the humeral trochlea
Radiographic studies of three cases of hypoplasia of the humeral trochlea were done. Several other anomalies were also detected, including a hypoplastic capitellum in case 2, a hyperplastic radial head in cases 2 and 3, and bulging of the loose joint capsule in case 3. Operations in cases
1 and 3, disclosed that ganglions and fibrous septa compressed the ulnar nerve. The cause of ulnar nerve palsy in patients with hypoplasia of the humeraf trochlea is thought to be associated with the high incidence of ganglions in hypoplastic elbow joints. The ganglion may play a role.
(J HAND SURG 1990;15A:1004-7.)
Keiji Sato, MD, and Takayuki Miura, MD, Nagoya, Japan
H ypoplasia of the humeral trochlea is a rare congenital anomaly of the elbow joint. Only four cases have been reported in the English-language lit- erature and all were Japanese patients. . However, 44
cases have been reported in Japan; the first was reported in 1927 by Saito.3 This rare malformation has been found exclusively in Japanese subjects. Three cases of hypoplasia of the humeral trochlea are reported and the pathogenesis of ulnar nerve palsy and the high incidence of associated ganglion is discussed.
Case 1. The patient, a 31-year-old, left-handed man con- sulted our hospital complaining of pain on the medial side of his left elbow and numbness of the ulnar side of the left hand.
He first recognized a deformity of both his elbow joints in junior high school. At the age of 21 a small subcutaneous
tumor was found on the medial side of his left elbow joint. Tapping the tumor caused pain to radiate to the tip of the ring
and small fingers. Puncture of the nodule was twice done at another hospital, and the subjective symptoms were relieved
for a while. X-ray films of the left elbow joint in the anteroposterior
view (Fig. 1) clearly demonstrated hypoplasia of the humeral trochlea on both sides and the olecranon was slightly shifted towards the medial side. In the lateral view (Fig. 2), there
From the Department of Orthopaedic Surgery, Nagoya University, School of Medicine, Nagoya, Japan.
Received for publication Feb. 23, 1989; accepted in revised form Dec. 4, 1989.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
Reprint requests: Keiji Sato, MD, Department of Orthopaedic Sur- gery, Nagoya University, School of Medicine, 65 Tsurma-cho, Showa-ku, Nagoya 466, Japan.
Fig. 1. Anterorposterior x-ray view shows the hypoplasia of the humeral trochlea and slight medial shift of the olecranon. In the lateral view, the humeroradial joint also seems to be hypoplastic .
seemed to be hypoplasia of the humeroradial joint in both sides.
On examination the left elbow joint was normal in shape and the carrying angle was 0 degrees. Joint instability was not demonstrated even in the flexed position. The range of motion of his elbow joint showed mild restriction in every direction, extension - 30 degrees on the right and - 20 de- grees on the left, flexion 135 degrees on the right and 130 degrees on the left, supination 90 degrees on both sides, pronation 50 degrees on the right and 60 degrees on the left. A small subcutaneous lump was palpable on the medial side of the right elbow, but Tinels sign was negative. Two small nodules were discovered on the medial side of the left elbow and one showed a positive Tinels sign. The patient com- plained of hypesthesia over the ulnar side of the left forearm, but claw-finger deformity was not present. Muscle atrophy was detected in the hypothenar and the first interosseous mus- cle of the left hand. Muscle strength in abduction was rated good in the manual muscle test. Froments sign was not dem- onstrated clearly, and grasping power was slightly decreased on the left side at 46 kg, compared with 50 kg on the right
1004 THE JOURNAL OF HAND SURGERY
Vol. 15A, No. 6 November 1990 Hypoplasia of humeral trochlea 1005
Fig. 2. Anterorposterior x-ray view of case 2. Only the left side was affected and clearly demonstrated the hypoplasia of the humeral trochlea.
side. Nerve conduction velocity was delayed on the left side at 36 m/set, compared with 50 m/set on the right in the
ulnar nerves. An operation on October 2 1, 1983 showed under the sub-
cutaneous tissue, a small ganglion (0.5 X 1.0 cm), which was resected. A fibrous bundle over the flexor carpi ulnaris compressed the ulnar nerve, and a pseudoneuroma was pres- ent. Resection of this fibrous bundle and release of the ulnar
nerve revealed another ganglion (1.5 X 1 .O cm) under the ulnar nerve, and this was also resected.
The postoperative course was satisfactory. The pain sub- sided just after the operation and muscle strength recovered, but slight numbness on the palmar side of the left small and ring finger persisted.
Case 2. The patient, a 34-year-old woman, visited our hospital with a complaint of pain, present even at rest, in the left elbow region. She had recognized a deformity of her left elbow at the age of 6. Vague pain had continued from the age of 15 years, and the pain gradually became worse.
On examination several nevi were detected in her left arm and forearm. The left elbow joint showed a varus deformity, and the carrying angle was - 10 degrees. There was a lim- itation of motion, with a loss of 13 degrees in extension but supination and pronation were 90 degrees. Grasping power was 29 kg on the right and 21 kg on the left. Touch and pin prick sensibility was normal, but subjective numbness existed over the ulnar side of the left palm. Lateral instability was demonstrated. Neither muscle atrophy nor claw finger defor- mity was detected.
X-ray films showed a congenital anomaly of the left elbow joint. The main deformity was thought to be hypoplasia of the humeral trochlea (Fig. 2). but several other anomalies were also detected. One was a hypoplastic humeral capitel- lum, and the other was a hyperplastic radial head with a
Fig. 3. Lateral view in case 2. The humeral capitellum is
also hypoplastic, but the radial head is reversely hyperplastic and is convex on its joint surface.
convex deformity of the joint surface (Fig. 3). These minor deformities were clearly demonstrated by comparison of the x-ray films of both sides. The pain was effectively alleviated
by oral intake of antiinflammatory analgesics, and surgery
was not indicated. Case 3. The patient was a right-handed, 46-year-old man,
who consulted our hospital complaining of numbness over the palmar side of his right small and ring fingers of 9 months duration. He first recognized a deformity of his left elbow at the age of 12. Examination of his left elbow showed a cubitus
varus deformity with a carrying angle of - 15 degrees. The right elbow was normal. Lateral instability was clearly dem- onstrated even in maximum extension. The range of motion of both his elbow joints was restricted in flexion and exten- sion. Flexion was 120 degrees on the right side and 125 degrees on the left. Extension was - 20 degrees on the right and - 15 degrees on the left. A small, elastic soft tumor was palpable under the skin on the medial side of the right elbow. Tinels sign was positive, and pain radiated over the distal ulnar nerve region. Muscle atrophy was present in the right thenar muscle and the right first interosseous muscle. The strength of finger abduction was good. Froments sign was clearly positive on the right. Mild claw-finger deformity was also observed on the right side. Grasping power was weak on the right i.e., 28 kg compared with 36 kg on the left side. Nerve conduction velocity of the right ulnar nerve was de- layed at the level of the cubital tunnel.
Anteroposterior x-ray films (Fig. 4) showed that the hu- meral trochlea was hypoplastic in both elbow joints, but the right radial head was conversely hyperplastic (Fig. 5). Ar- thrography of the right elbow showed that the joint capsule was loose and part of it bulged towards the medial side of the elbow joint like a ganglion (Fig. 6).
At operation, December 13, 1988, the base of the ganglion was found firmly attached to the joint capsule and also ad- herent to the ulnar nerve. Just distal to this lesion, the fibrous septum of the flexor carpi ulnaris constricted the ulnar nerve and a pseudoneuroma was found. Resection of the fibrous bundle of the flexor carpi ulnaris and the ganglion with neu-
1006 Sato and Miura The Journal of
Fig. 4. Anteroposterior x-ray view of case 3 shows hypoplasia of the humeral trochlea on both sides.
Fig. 5. Lateral view of case 3 shows similiar changes as in case 2. The humeral capitellum is hypoplastic but, the radial head is reversely hyperplastic
rolysis and anterior transposition of the ulnar nerve yielded good results.
Hypoplasia of the humeral trochlea seems to be a rare condition, and, including our three cases, 46 cases have now been reported. We exclude a case reported by Mead3 of an extremely rare aplasia of the humeral trochlea. Thirty cases were male and the other 16 cases were female. Twenty-five cases were affected bilater- ally, and 21 cases were unilateral.
The shape of the elbow was noted in 57 cases. Among them, a majority, 41 (72%) hands, showed the cubitus varus deformity. The cubitus valgus deformity was found in only five cases, or 9%. The other 11 cases, or 18%, had a diagnosis of normal shape.
Fig. 6. Arthrography of the right elbow joint of case 3. White arrow demonstrates the ganglion in the sulcus ulnaris bal- looned out from the joint capsule.