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The purpose of this study was to describe a technique of end-to-end rigid fixation of the distal radius to the proximal ulna. The shortening and radioulnar overlap in this technique yield a high union rate, large corrections, and few complications.
This retrospective chart review from 2 centers was undertaken in 39 patients (40 forearms) who underwent one-bone forearm operations between 2005 and 2019. There were 25 male and 14 female patients, with a mean age at surgery of 9.7 years (range 3 to 19 years; SD, 4.5 years). The diagnoses included brachial plexus birth injury, spinal cord injury, arthrogryposis multiplex congenita, cerebral palsy, ulnar deficiency with focal indentation, multiple hereditary exostosis, acute flaccid myelitis, and tumor.
The average follow-up was 33.5 months (1.2–110.1 months; SD, 27.1 months). The 36 forearms in supination had an average supination contracture of 93° (range, 15° to 120°; SD, 15.4°). The 4 pronated arms had an average pronation contracture of 80° (range, 50° to 120°; SD, 29.2°). The average postoperative position was 22.8° of pronation (range, –15° to 45°; SD, 12.9°). The average correction obtained with our technique was 113° (range, 20° to 145°; SD, 22.9°). Radiographic union was demonstrated in 32 (80%) of the one-bone forearms by 10 weeks, 39 (97.5%) by 16 weeks, and 40 (100%) by 24 weeks. One patient had peri-implant fractures prior to union. No forearms required reoperation for nonunion.
One-bone forearm performed with this technique allows reliable healing and a large degree of correction.
Forearm rotational deformities can occur as a result of skeletal trauma, congenital conditions, or neurologic injury. The position of forearm supination or excessive pronation is problematic for activities of daily living, including typing, writing, dressing, use of an electric wheelchair, and bimanual activities.
In forearm supination, the shoulder can compensate with abduction. Likewise, with pronation, the shoulder can compensate with shoulder adduction, but this is limited since adduction beyond neutral is blocked by the body. Additionally, some compensation is possible through radiocarpal rotation to improve the hand position. A study simulating a one-bone forearm in unaffected individuals concluded that 30° of pronation provided the best function for writing and working with small objects using the dominant arm.
In patients with neurologic deficits, the position of pronation also facilitates tenodesis pinch and grasp.
Supination contractures have been treated by a variety of methods, including osteoclasis, osteotomy of the proximal or distal radius, osteotomies of the radius and ulna, release of the interosseous membrane combined with biceps rerouting, biceps rerouting alone, and one-bone forearm formation.
As a general principle, less severe contractures, especially those with supple passive motion, have been treated with soft-tissue procedures. Severe fixed contractures are treated with bony procedures, with or without concurrent soft-tissue rebalancing. The correction of pronosupination reported after bony procedures has ranged from 69° to 90°, with 1 cadaveric study demonstrating that osteotomies of the radius and ulna can only provide approximately 100° of correction, with further correction limited by the interosseous membrane.
The creation of a one-bone forearm with rigid internal fixation creates a statically stabilized construct that eliminates forearm rotation and has potential for low recurrence and substantial correction, as can be required for severe supination deformities.
The one-bone forearm can be created by several different techniques. Chen et al
defined the creation of a radioulnar synostosis as the side-to-side juxtaposition of the radius and ulna. The outcome of side-to-side fusion with the use of an intercalary bone graft was recently described for a variety of forearm pathologies, including brachial plexus birth injury (BPBI) and multiple hereditary exostoses.
No specific surgical technique is currently considered the gold standard, and previous reports have demonstrated a high complication rate, including nonunion, infection, and proximal radial impingement.
The purpose of this investigation was to describe the experience of reliable union seen in our series using a modification of the one-bone forearm reconstruction technique of rigid end-to-end fixation previously described.
we used this technique as the index procedure to treat 40 forearms in 39 patients with neurologic deficits or instability, and as a salvage for 1 patient who had deformity recurrence after radial and ulnar osteotomies. We hypothesized this technique could result in larger pronosupination correction, a higher union rate, and fewer complications compared to previously described techniques.
Materials and Methods
The institutional review boards at Shriners Hospital for Children and Barcelona University Children's Hospital HM Nens granted approval prior to starting the study, and the Strengthening the Reporting of Observational Studies in Epidemiology guidelines were followed throughout this investigation. This retrospective review included patients who had one-bone forearm reconstructions between January 1, 2005, and December 31, 2019, from 2 centers. We identified 46 patients (50 forearms), 28 males and 18 females. Of these, 7 patients (10 forearms) were excluded due to a short follow-up or the absence of final radiographs. One patient had bilateral operations, resulting in inclusion of a total of 40 forearms (26 right and 14 left) in 39 patients (25 males and 14 females). Indications for the operation included a severe supination (Fig. 1) or pronation contracture with a lack of preexisting active forearm motion that precluded functional use of the hand.
Patients were supine with the operative extremity on a hand extension table. The limb was exsanguinated with simultaneous tourniquet application. Examination under anesthesia confirmed the forearm position using the epicondylar axis and radial and ulnar styloids for reference.
A volar curvilinear incision was made over the flexor carpi radialis tendon distally and the ulna proximally. Full thickness skin flaps were elevated, and 2 distinct deep intervals were connected deep to the tendons along the interosseous membrane. The radial interval was made through the flexor carpi radialis fascia and subsheath to access the radius. The pronator quadratus and flexor pollicis longus origins were elevated to expose the radial diaphysis while preserving the periosteum. The ulnar interval was made between the flexor carpi ulnaris and palmaris longus/flexor digitorum superficialis after identifying the ulnar neurovascular bundle deep to the flexor carpi ulnaris (Fig. 2). The ulna was exposed by elevating the flexor digitorum profundus origin. Care was taken to protect the anterior interosseous neurovascular bundle.
In patients with a longstanding, high-level spinal cord injury or amyoplasia, the forearm muscles were often denervated and replaced by fat or fibrotic muscle fibers with atrophic and atretic tendons. The median nerve and radial and ulnar neurovascular structures were protected throughout the procedure. Prior to performing the osteotomy, a 6-hole low-contact dynamic compression plate (Synthes USA) of the appropriate thickness (2.4 mm, 2.7 mm, or 3.5 mm) for the patient’s size was provisionally applied to the volar aspect of the radius to drill the distal holes.
The plate was then removed and contoured. The periosteum of the radius was split longitudinally but kept in continuity, and Hohmann retractors were applied to protect the soft tissues. A sagittal saw was used to create a transverse osteotomy just proximal to the pronator quadratus. The ulna osteotomy was similarly performed, but 1 centimeter proximally to the radial osteotomy site (Fig. 3). By creating the osteotomies at different levels within the forearm, apposition of the distal radius to the proximal ulna shortens the forearm. This shortening slackens the soft tissues, allows increased rotational correction, and reduces the risk of compartment syndrome. The proximal radius and distal ulna segments are felt to contribute to union by adding vascularized bone at the osteosynthesis site, thereby increasing the area for fusion.
The plate was then reapplied to the radius through the previously drilled holes, and the distal radial segment was apposed to the proximal ulna. Forearm orientation was set by rotating the radius-plate construct relative to the ulna. This was held using a clamp to assess the forearm position. Rotational correction was made according to the preoperative plan and adjusted based on intraoperative findings. When the goal of approximately 30° of pronation was achieved, the plate was then fixed to the ulna using the remaining screw holes.
The proximal radial segment was beveled at its distal end with the sagittal saw to lay flat against the osteosynthesis site. The cortex of the newly formed single-bone construct adjacent to the beveled radius was rasped, and the proximal radius was lagged to the osteotomy site using suture or a compression screw (Fig. 4). The distal ulna segment was held by the intact distal radioulnar joint and soft tissues and, in most cases, healed to the fusion site in an X configuration (Fig. 5).
The elbow was then taken through a range of motion to evaluate for radiocapitellar impingement. Each patient’s elbow function was considered on a case-by-case basis, and impingement was addressed by excision of the proximal radius if it was thought likely to limit postoperative function or if the patient had pain at the radiocapitellar joint preoperatively. The majority of cases had either a reduced radiocapitellar joint or an incongruent joint that did not limit flexion, and the proximal radius was left intact because it was felt to contribute to lateral elbow stability. Additionally, patients with more passive elbow flexion than active elbow motion did not have the radial head resected, even if it was not reduced because the radial head influences lateral collateral ligament tension.
After final fluoroscopic images, closure, and the application of dressings, the extremity was placed into an above-elbow splint.
Digital range of motion exercises were started right after surgery. The extremity was immobilized in a long-arm splint and then a long-arm cast until 4–6 weeks after surgery. Then, a removable Munster orthosis was fabricated, and elbow motion begun.
The forearm position in each patient was measured before and after surgery by the operating surgeon or a certified hand therapist (Fig. 6). Pronation was measured at the wrist between the radial and ulnar styloids with the elbow in 90° of flexion.
All of the available radiographic studies were reviewed by the attending surgeon (S.H.K., F.S., and D.A.Z.) to determine the presence of union or nonunion. Hardware failure, peri-implant fracture, symptomatic or delayed nonunion, and infection were indications for further treatment. Union was determined to have occurred when there was both a lack of tenderness and abundant callus or crossing trabeculae at the osteotomy site on radiographs.
A total of 40 arms in 39 patients were included (Table 1). The average age at the time of surgery was 9.7 years (range, 3–19 years; SD, 4.6 years). There were 25 male patients and 14 female; there were 14 left and 26 right arms. The average follow-up was 33.5 months (range, 1.2–110 months; SD, 27.1 months). The presenting diagnoses for each arm in the cohort were as follows: BPBI (n = 24), spinal cord injury (n = 5), arthrogryposis multiplex congenita (n = 2), cerebral palsy (n = 3), ulnar focal cortical indentation (n = 2), multiple hereditary exostoses (n = 1), acute flaccid myelitis (n = 1), and tumor (n = 2). One patient with BPBI had previously undergone a radial and ulnar osteotomy for a supination contracture. However, due to hardware failure, the supination contracture recurred and was then successfully corrected with a one-bone forearm reconstruction. One patient with cerebral palsy was treated for a chronic Essex-Lopresti injury with staged ulnar lengthening and then a one-bone forearm. The distal ulna was resected in 2 patients: 1 with a spinal cord injury and the other with cerebral palsy.
Based on the clinical exam and radiographs, 20 extremities had a concern for preoperative radiocapitellar impingement due to a dislocated (n = 19) or subluxated (n = 1) radial head. Three extremities underwent radial head resection to alleviate the mechanical block to flexion from radial head impingement. The diagnoses for the patients with radial head resection were ulnar focal cortical indentation (n = 2) and BPBI (n = 1). The remaining 17 extremities with preoperative radiocapitellar incongruity were not resected. The decision to resect the proximal radius in patients with incongruent joints was at the discretion of the attending surgeon and was determined based on the combination of a preoperative evaluation of pain at the elbow and an intraoperative assessment for mechanical block by ranging the elbow. Patients that did not have a mechanical block from impingement despite an incongruent joint were left with the proximal radius unresected. There were no new cases of radial head subluxation or dislocation after the one-bone forearm reconstruction.
The 36 forearms in supination had an average supination contracture of 93° (range, 15° to 120°; SD, 15.4°). The 4 pronated arms had an average pronation contracture of 80° (range, 50° to 120°; SD, 29.2°). For all patients, the average preoperative forearm was supinated 76° (range, –120° to 120°; SD, 55.1°). The average corrected position was pronated 22.8° (range, –15° to 45°; SD, 12.3°). The average correction obtained was 113° (range, 20° to 145°; SD, 22.9°).
Complications included 2 patients who sustained peri-implant fractures after falls and required treatment; 1 patient had a fully healed one-bone forearm but required revision open reduction and internal fixation for a new fracture 7 years after his one-bone forearm reconstruction. The other peri-implant fracture was treated in a cast after a fall in the presence of loose hardware but maintained the corrected forearm rotation. One patient showed marginal necrosis of the surgical wound; however, this healed without a need for additional surgery. All reconstructed forearms healed without the need for any further surgical intervention. Radiographic union was demonstrated in 32 (80%) one-bone forearms by 10 weeks, 39 (97.5%) by 16 weeks, and 40 (100%) by 24 weeks. At final follow-up, all patients were radiographically united without loss of correction.
The loss of forearm rotation, with or without fixed pronation or supination contracture, impairs upper extremity functions.
A poorly positioned hand limits grasp and bimanual object manipulation. Forearm pronation is a more functional position for most activities, and 30° of simulated pronation has been shown to be optimal.
Supination contractures can result from neurologic deficits and the imbalance of muscular forces on the forearm axis. This is especially evident in cervical spine and brachial plexus injuries with recovery of upper trunk functions. In both instances, there is recovery of forearm supination (biceps [C5, C6] and supinator [C6]) but no recovery of forearm pronation (pronator teres [C7] and pronator quadratus [C8, T1]).
Multiple techniques have been described to gain pronation for fixed supination contractures, including soft-tissue and bony procedures. Although soft-tissue rebalancing may be effective in less severe supination contractures, particularly those with a functioning biceps, bony correction is required in fixed and in severe contractures. Forearm osteoclasis and gradual correction via serial casting provides some correction; however, recurrence is common without rigid fixation and soft-tissue rebalancing.
Similarly, osteotomies can provide correction but are limited by the interosseous membrane and other soft tissues. Deformity recurrence, delayed union or nonunion, and forearm instability have been common complications.
Average correction was 86°, but 6 patients had hardware failure that resulted in a mean loss of correction of 18°. Even patients without hardware failure had some loss of correction. Currently, we reserve dual osteotomies for corrections of less than 90° and only if there is the possibility of rebalancing the forearm with tendon transfers. A requirement for greater correction or the infeasibility of soft-tissue rebalancing options are indications for a one-bone reconstruction.
The one-bone forearm reconstruction has traditionally been used as a salvage procedure after traumatic injuries, and was first described in 1921.
One-bone forearm as a salvage was recently described for pediatric patients with recalcitrant problems—including multiple hereditary exostoses and BPBI, among other pathologies—to treat longitudinal instability, loss of motion, and painful radial head dislocations. Their technique involved a side-to-side arthrodesis to preserve forearm bulk, with an intercalary graft and regular excision of the proximal radius and distal ulna. They also found that complications are rare in younger patients.
Their technique was similar to ours, but they used a dorsal approach and cancellous autograft from the remaining proximal radius and distal ulna. We prefer to shorten and overlay the proximal radial stump across the osteosynthesis site to promote union and limit proximal radial impingement. Their series also had few patients who required proximal radius resection for impingement.
The technique described here allows precise control of the pronosupination correction, excellent union, and the ability to gain greater rotation compared to other techniques. The modest shortening and proximal radius on-lay are key features of the technique. Although only 3 forearms had a proximal radius resection, assessing possible impingement should be emphasized as an important preoperative and intraoperative consideration. Furthermore, the low complication rate in younger patients is not unique to this series and may be related to the robust periosteum.
The average correction obtained, 113°, is larger than those previously published. This magnitude of correction is not always necessary, and final position is the factor that may improve function. The majority of forearms (35 forearms) in this cohort had severe (≥80°) supination contractures, as opposed to pronation contractures (4 forearms), explaining the need for large corrections to obtain a final pronated position.
This study has fundamental limitations, including the lack of function and patient-reported outcome measures. The retrospective design may limit sensitivity in detecting findings other than forearm position, such as elbow symptoms. Additionally, we are unable to draw conclusions regarding the clinical impacts of the altered forearm position or the one-bone forearm. Furthermore, the findings may be limited by the heterogeneous diagnoses, small sample size, and the variation in the follow-ups due to the nature of the geographically remote referrals in our practice. Complications may also have been undetected if patients received postoperative care elsewhere. Prior and concurrent procedures were not controlled for in measuring the operative correction, but would have been unlikely to have increased the correction required during the one-bone reconstruction, since prior interventions would have had similar goals of improving the hand position. We recommend follow-ups with regular radiographs until radiographic union, and this is particularly important if there is a concern for new symptoms at the surgical site. While there were no new cases of proximal radial instability after surgery, there were limited data to evaluate elbow functions. Lastly, we have shown reliable union, but the follow-up intervals were not designed to determine the time to union.
One-bone forearm reconstruction by the described technique allows for reliable correction of both large and small rotational forearm deformities and avoids recurrence. Furthermore, one-bone forearm reconstruction may be indicated as a primary treatment, and not just as a salvage operation, in select pediatric populations. The creation of the radial on-lay and lagging it to the one-bone osteosynthesis site may be important to enhancing union, in addition to preventing postoperative proximal radioulnar joint instability or new impingement. While this cohort had a low complication rate, it must be emphasized that this is a technically challenging operation and should only be performed by those trained in treating pediatric upper extremity deformities.
All figures and photographs are courtesy of Shriners Hospital for Children (Philadelphia, PA; Brian O’Doherty, photographer).
Optimal position for the one-bone forearm. An analysis using a hinged brace in normal subjects.