If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
To describe the clinical features, radiologic findings, differential diagnosis, and surgical treatment of a congenital flexion deformity of the middle, ring, and little fingers. The cause of the condition is the aberrant origin of the flexor digitorum profundus, leading to a congenital contracture of the ulnar digits.
Methods
We reviewed 8 patients with congenital contracture of the ulnar digits. The mean age at the time of surgery was 14 years. An examination revealed a flexion contracture of the middle, ring, and small fingers. Plain radiographs, 3-dimensional computed tomography, magnetic resonance imaging, and ultrasound were used to characterize bony and soft tissue pathology. Surgical treatments included resection of the aberrant origin and a muscle-sliding procedure.
Results
Bony prominence on the proximal ulna was seen in the plain radiographs and/or 3-dimensional computed tomography. A cord that extended from this bony prominence to the tendons of flexor digitorum profundus was revealed in the magnetic resonance imaging. The bony prominence and the cord were also seen using ultrasound. The median time of patient follow-up was 1.7 years. A simple resection of the tendinous origin only resulted in a release in 2 patients who were 4 years old. Older patients required a further muscle-sliding procedure. The average grip strength ratio on the contralateral side was 82%.
Conclusions
Congenital contracture of the ulnar digits is a new congenital flexion deformity involving the middle, ring, and small fingers. Bony prominence on the proximal ulna is the key finding for establishing its diagnosis and distinguishing it from an ischemic contracture. We recommend treating this surgically at 12 years of age or older after the phase of rapid growth of the extremities. We recommend the resection of the aberrant origin, combined with a muscle-sliding procedure, as the treatment of choice, even for young patients.
reported a case of flexion deformity involving the long and ring fingers that was caused by the shortening of the “tendon apparatus” of the long and ring fingers. Takagi et al
first reported a case of congenital flexion deformity of the middle, ring, and little fingers, with an aberrant origin of the FDP in 2008. Since then, similar cases have been reported.
Cases that we have seen have been misdiagnosed as ischemic contracture. Because it is a rare occurrence, we speculate that the awareness of the congenital causes of digit flexion contracture is limited. It remains unknown how the aberrant muscle origin limits the extension of the involved fingers and what the anatomical and pathomechanical causes are that differentiate it from an ischemic contracture. We reviewed this via imaging-based examinations, including radiographs, ultrasound, 3-dimensional computed tomography (3D CT), and magnetic resonance imaging (MRI), as well as other clinical manifestations to achieve more comprehensive knowledge of this entity. We identified this clinical condition as a congenital contracture of the ulnar digits (CCUD).
Materials and Methods
This retrospective study was approved by the institutional review boards of the hospitals involved. Informed consent was obtained from each patient or their parents.
From 2007 to 2019, 8 patients with CCUD were treated at our hospitals. There were 7 boys and 1 girl, with a median age of 12.5 years (range: 4–30 years). The left forearm was involved in 7 patients. According to the patients’ and/or their parents’ description, the deformity occurred at around a mean age of 1.6 years (range: 1–3 years). No parents reported complications with delivery or a previous history of injuries to the involved limb. There was also no family history of similar clinical conditions. The deformity eventually progressed with growth, prompting medical attention at around the age of 6–9 years. All the patients had been diagnosed with ischemic contracture at their local clinics. One patient was advised to wear an extension splint, without any effect. Three patients had undergone step-cut lengthening of the flexors of the middle, ring, and little fingers at their local clinics between the age of 7 and 10 years (Fig. 1); but in all the cases, the flexion deformity of the 3 fingers recurred and gradually progressed (Table 1).
Figure 1Flexor contracture of the middle, ring, and little fingers. There was a surgical scar at the distal forearm, with which the step-cut lengthening of the flexors had been performed. A The hand lay in a rest position, and the flexor tension of the middle, ring, and little fingers was obviously higher than that of the index finger. B The patient could fully fist his hand. C The middle, ring, and little fingers could be extended with the wrist in flexion. D The extension of the middle, ring, and little fingers was limited with the wrist in the neutral position.
An examination showed extrinsic flexor tightness of the middle, ring, and little fingers. Full extension was not possible with the wrist in the neutral or extended position, but the patients could extend the 3 fingers with the wrist in flexion (Fig. 1). Other than the extrinsic flexor tightness, there were no other neuromuscular deficits in the hand. The active flexion and extension of the wrist, thumb, and index fingers were nearly normal.
Radiographs were obtained and/or 3D CT was performed to illustrate the deformity of the proximal ulna and the wrist. We used Doppler ultrasonography and MRI to evaluate the forearm muscle contracture and the extension of the abnormal band.
Surgical intervention
All the patients received surgical treatment. Surgery was performed under brachial plexus anesthesia (for adults) or general anesthesia (for children). An incision was made from a point several centimeters above the supracondylar region, distally through the middle portions of the forearm. The medial epicondyle, flexor-pronator origin, ulnar nerve, and brachial artery and vein were identified. The ulnar nerve was first dissected and protected. The flexor carpi ulnaris was elevated to visualize the ulna. Bony prominence on the anteromedial aspect of the proximal side of the ulna could be detected. There was an anomalous tendinous band that originated from this bony prominence and connected with an independent muscle belly of the FDP, which looked normal. When the tendinous origin was elevated, the middle, ring, and little fingers flexed. A simple resection of the tendinous origin resulted in a full release of the contracture only in 2 patients who were 4 years old. The other patients required a further muscle-sliding procedure for the flexor muscles to achieve a thorough release that allowed the fingers to be fully passively extended even with the wrist extended to 60° (Fig. 2). For the 3 patients who had previously undergone step-cut lengthening of the flexors elsewhere, another incision around the wrist was made to release flexor tendon adhesions.
Figure 2A The aberrant origin of the FDP attached to the bony prominence of the ulna. The thick arrow marks the bony prominence of the ulna. The thin arrow indicates the aberrant tendinous origin of the FDP. B After the aberrant origin was resected and the muscle-sliding procedure was performed in an adult patient, the middle, ring, and little fingers could be passively fully extended even with the wrist in extension. C In a young patient, a small incision was enough to explore and resect the aberrant origin of the FDP. A clamp was inserted under the aberrant origin of the FDP. The middle, ring, and little fingers lay in a rest position. D The aberrant origin was lifted by the clamp, and the middle, ring, and little fingers could be fully flexed while the thumb and the index finger remained in the rest position. It was also obvious that the anomalous tendinous band connected with an independent FDP muscle belly. E For the young patient, a simple resection of the tendinous origin resulted in a thorough release.
After the surgery, the wrist and fingers were placed in a plaster splint, with the wrist extended to 30° and the fingers extended to 0°, for 3 weeks and then in a dynamic splint for another 4 weeks. Early active range of motion exercises of the wrist and all fingers were begun on the second postoperative day. The patients were encouraged to actively perform the exercises 3 times a day (for 5–10 minutes each time) during the first week and then advance as tolerated.
Results
Imaging examination results
All the patients had anteroposterior and lateral radiographs taken of the forearm. Five also underwent 3D CT of their forearms. Three patients underwent an ultrasound examination. Two patients underwent MRI. The radiographs and 3D CT showed a small bony prominence on the proximal part of the ulna in each patient as the only positive finding. The size of this prominence appeared to be related to the age of the patient. In very young patients, the bony prominence was so small that it was only visible by 3D CT. In 1 adult patient, the bony prominence was quite long and broken in the middle. In 2 adult patients, adaptive volar intercalated segmental instability was found (Fig. 3). In a properly oriented section of the MRI, a uniform cord was found extending from the bony prominence to the tendons of the FDP around the wrist. In 3D CT, the cord appeared less distinct. With ultrasound, we could see the bony prominence and the cord arising from the prominence, but it was very difficult to track the cord to the wrist in the panoramic ultrasound image because of the low resolution of the ultrasound (Fig. 4).
Figure 3The radiograph and computed tomography (CT) scan show bony prominence in the proximal ulna. The arrows indicate the bony prominence. A 3D CT shows bony prominence in the medial and anterior aspects of the proximal side of the ulna. B The coronary CT scan of the ulna shows that the bony prominence originated from the cortical bone of the ulna. C The radiograph shows long bony prominence on the proximal ulna. D The bony prominence was broken in the middle. E 3D CT shows long bony prominence in an adult patient. F 3D CT shows tiny bony prominence in a 4-year-old patient. G The lateral radiograph shows mild volar intercalated segment instability in an adult patient.
Figure 4Illustration of the aberrant cord. A Computed tomography shows a blurry image of the aberrant cord (thin arrow) that is attached to the bony prominence (thick arrow). B MRI shows a very clear uniform cord that extends from the bony prominence to the tendons of the FDP around the wrist (thin arrow). The thick arrows indicate the tendons of the FDP of the middle and little fingers. C The panoramic ultrasound image shows the bony prominence (thick arrow) and the cord (thin arrows), but it was difficult to the track the cord to the wrist.
The patients were followed up for a median of 1.7 years (range 0.5–12 years). All the patients could fully extend their fingers within several days after the operation. At the final follow-up, the adult patients could actively extend their fingers with the wrist extended to 20°–40°. For young patients in whom only the resection of the aberrant tendon origin was carried out, there was a slight limitation of the extension of the middle and ring fingers with the wrist extended to 0° (Fig. 5). The average grip strength ratio on the contralateral side was 82% (range 72%–100%).
Figure 5A–C An adult patient could actively extend their fingers when the wrist extended to 40° and was fully flexed at a follow-up period of 1 year after the operation. The function of the FDP of the middle, ring, and little fingers was good. D, E A 4-year-old patient could extend and flex his fingers 2 weeks after the operation with active flexion impairment of the DIPJ of the ring finger. F, G Sixteen months after the operation, the patient could extend and flex his fingers with the DIPJ of the ring and middle fingers flexed. DIPJ, distal interphalangeal joint.
Congenital flexion deformity of the middle, ring, and little fingers with an aberrant origin of the FDP is a rare entity. In our department, on average, there are 8,200 surgical cases per year, suggesting an incidence of CCUD of approximately 8.1 in 100,000. During the same period, the incidence of ischemic contracture was 2.8 in 1,000.
The cause of this anomaly is unclear. In our small series, we found that boys and the left forearm tended to be more involved, but the reasons are unknown. The development of bony prominence on the ulna associated with an aberrant FDP origin might be similar to that of the supracondylar process and the Struthers ligament at the distal humerus.
In our experience, CCUD was uniformly misdiagnosed as an ischemic contracture. In our series, 3 patients had undergone step-cut lengthening of the flexors before the flexion deformity recurred and gradually progressed. Differentiation between the conditions should normally be relatively easy (Table 2).
Table 2Differential Diagnosis of CCUD and Ischemic Contracture
Differential Diagnosis
CCUD
Ischemic Contracture
Sex
Male dominant (7:1)
No difference
Involved limb
Left dominant (7:1)
No difference
Congenital or acquired
Congenital
Acquired
Onset of the disease
Childhood
Any age
History of trauma
No
Yes
Nature of the disease
Aberrant tendinous band tethering
Muscle and nerve ischemia
Fingers involved
Middle, ring, and little fingers
Any finger
Wrist involved
No
Possible
Intrinsic muscle involved
No
Possible
Nerve involved
No
Possible
Functional impairment
Mild
Mild to severe
Adaptive changes for juvenile patients
Shortening of the flexor digitorum superficial and profundus as well as mild volar intercalated segmental instability
Shortening of the forearm, deformity of carpi, joint contracture, and deficits of the palmar skin of the wrist and fingers
Disease progression after onset
Gradual progress with growth
Progress soon after onset and relieved to some extent later
Radiograph or 3D CT findings
Bony prominence on the proximal part of the ulna
Possible shortening of the involved forearm
Non-operative treatment
No effects
Passive stretching technique might be useful in some cases
Intervention treatment
Resection of the aberrant origin of the FDP and a muscle-sliding procedure
Although a neonatal ischemic contracture can also lead to both the progression of flexion deformity with age and the recurrence of flexion deformity after the step-cut lengthening of the flexors, it is a different entity according to the case’s history, physical examination, and surgical exploration.
First, the patients’ parents denied any injury history in their infancy, and during our examination, we did not observe any skin lesion on the forearm, which is found in almost all cases of neonatal ischemic contracture.
Second, the flexor contracture in neonatal ischemic contracture initially involves superficial muscles, whereas in our cases, the tethering occurred mainly in the FDP.
Third, surgical exploration revealed that the flexor muscle belly was almost normal (Fig. 2). No fibrosis or scar tissue, both often seen in an ischemic contracture, was found. Fourth, an ischemic contracture usually involves a group of muscles; so, upon exploration, the involved area of fibrosis should be surrounded by relatively normal muscle fibers, but in CCUD, the tendinous band originates from bony prominence connected to an independent muscle belly (Fig. 2B). Trismus-pseudocamptodactyly syndrome, which is thought to be inherited as an autosomal dominant trait, can also lead to tenodesis in the forearm, but in our cases, there were neither trismus symptoms nor a positive family history.
Since the condition is caused by the tethering of an aberrant tendinous band originating from a bony prominence of the ulna, the deformity progresses with growth. In our series, the older patients described that there was rapid progression at around 6–9 years of age. However, for young patients with ischemic contracture, if a dynamic extension splint is properly used, we usually find that the involved forearm is shorter than the opposite. This was not observed in our cases.
In adults, because of the longstanding tethering of the FDP, the muscle belly of the FDP, and even flexor digitorum superficialis, cannot be fully stretched during growth. Therefore, we recommend treatment with the resection of the aberrant origin, combined with a muscle-sliding procedure. The long-term tethering of the FDP was also associated with mild adaptive volar intercalated segment instability in some of our cases. This might have limited the extension of the wrist to some extent.
For very young patients, the results were not as satisfactory as those in adult patients. One reason might be related to the growth of their forearms. We found that one 4-year-old patient could not actively flex the distal interphalangeal joint of the ring finger soon after the operation (Fig. 5E). But after 16 months, he could not fully extend the distal interphalangeal joint of the ring and middle fingers when the wrist was in the neutral position (Fig. 5F). We speculate that the aberrant tendinous band affected the ring finger more.
At final follow-up, we found that the patients could actively extend their fingers with the wrist extended to 20°–40°, which was not as good as the result immediately following the operation. This might have resulted from the reattachment of the aberrant tendinous band more distally. In children, if only resection was performed, the band could reattach just distal to the bony prominence, leading to worse results secondary to ongoing growth. Therefore, we suggest that the optimal surgical timing be at an age older than 12 years and that the resection of the aberrant origin of the FDP be combined with a muscle-sliding procedure, even for young patients.
The main limitation of this study is its small sample size; so, the extent to which our findings are in any way generalizable is unknown.
In conclusion, an accurate diagnosis of CCUD can be established according to the following criteria: a contracture of the ulnar digits first found in babyhood without any injury history; bony prominence on the proximal part of the ulna found in radiographs and/or 3D CT; and an anomalous tendinous band seen using ultrasound or MRI and identified during an operation. The optimal surgical timing should be at an age older than 12 years, after the rapid growth of the extremities finishes. The resection of the aberrant origin of the FDP, combined with a muscle-sliding procedure, should be the treatment of choice, even for young patients.
Acknowledgment
The authors thank Dr Edward C. Mignot, Shandong University, for linguistic advice.
References
Ultee J.
Hovius S.E.
Functional results after treatment of Volkmann’s ischemic contracture: a long-term followup study.
00371-3&id=gr1.jpg){kind=link}
00371-3&id=gr2.jpg){kind=link}
00371-3&id=gr3.jpg){kind=link}
00371-3&id=gr4.jpg){kind=link}
00371-3&id=gr5.jpg){kind=link}