Preoperative Computer Simulation and Patient-specific Guides are Safe and Effective to Correct Forearm Deformity in Children.

BACKGROUND: Posttraumatic and congenital forearm deformities in children can be difficult to appreciate in all planes. In cases of distal radioulnar joint instability and loss of forearm rotation, surgical correction is challenging. Advances in 3-dimensional printing allow creation of custom guides at a reasonable cost, enabling precise correction of the deformity in all planes. METHODS: Nineteen children with deformity of the forearm had corrective osteotomies performed using preoperative 3-dimensional computer modeling and patient-specific surgical guides. Surgicase software was used for 3-dimensional planning of the corrective osteotomy, by superimposing a mirror image of the unaffected side as a template. Based upon this planning, patient-specific surgical guides were manufactured. Radiographic and clinical outcomes were assessed. RESULTS: Three patients had a diagnosis of multiple hereditary exostoses, and one of Madelung's deformity. The remaining 15 patients had a diagnosis of fracture malunion. Average preoperative angulation of both the radius and ulna was 23 degrees. For the patients with fracture malunions, the time from injury to surgery ranged from 6 months to 8 years. Twelve patients underwent osteotomies of both the radius and ulna, 5 had osteotomies of the radius alone, and 2 had a single osteotomy of the ulna only. All osteotomies went on to unite and no patient lost range of motion. Preoperative arc of forearm rotation averaged 101 degrees (range 0 to 180 degrees). Postoperatively, this improved to 133 degrees (range 85 to 180 degrees). Eight patients had distal radioulnar instability preoperatively, all of which normalized after surgery. There were 4 complications: 1 hypertrophic scar, 1 subject with extensor pollicis longus weakness, and 2 transient sensory losses in the superficial radial nerve distribution. CONCLUSIONS: This case series demonstrates that 3-dimensional computer modeling permits complex and multiple osteotomies to be done safely to achieve deformity correction in children. Limitations in forearm rotation and distal radioulnar malalignment can be reliably improved using this technique. LEVEL OF EVIDENCE: Level IV-retrospective case series.

The use of computer-aided design and 3-dimensional models in the treatment of forearm malunions in children.

Computer-aided design has several orthopedic applications. In this article we propose the use of computer-aided design to address the problem of forearm malunions in children. Traditional methods of planning forearm osteotomies utilize 2-dimensional radiographs, however, this is not a reliable method to address rotational deformities. Our method involves collaboration with clinical engineers at Materialise (Leuven, Belgium) to produce patient-specific cutting jigs using preoperative computed tomographic scans and 3-dimensional printing technology. This method allows for precise planning of complex and multiple osteotomies while decreasing the need for intraoperative decision making. Our initial results with this technique demonstrate improvements in forearm rotation and distal radioulnar joint stability.

Very distal radial osteotomy for Madelung's deformity.

Madelung's deformity results from arrested or slowed growth of the volar-palmar portion of the distal radial epiphysis. The deformity is characterized by increased volar and ulnar tilt of the articular surface of the radius and a bow of the distal radius in a palmar direction. When Madelung's deformity produces pain and interferes with function, correction of the deformity of the radius and secondary overgrowth of the ulna is desirable. Although osteotomy of the radius near the junction of the middle and distal thirds allows correction of the bow of the radius and limited correction of palmar tilt, it does not permit correction of ulnar tilt. We describe a very distal radial osteotomy that permits correction of the 3 deformities of the distal radius independently; correction of palmar tilt, ulnar tilt, and the bow of the radius are selected individually. The inherent flexibility makes the procedure technically challenging but allows for maximum independent correction of the components of Madelung's deformity. Early results indicate the procedure provides relief of pain and improved appearance with few complications.

Abductor digit minimi opponensplasty: technique, modifications, and measurement of opposition.

The abductor digiti minimi is one of several muscles described as transfers for restoration of thumb opposition, a critically important function. This operation, also known as the Huber opponensplasty, is most commonly used for reconstruction of opposition in children with type 2 or 3a thumb deficiency, when it is often combined with Z-plasty of the thumb-index web space and metacarpophalangeal ulnar collateral ligament reconstruction. In our experience this operation reliably improves thumb opposition for children with this thumb deficiency.

Madelung's deformity: diagnostic thresholds of radiographic measurements.

PURPOSE: Although the x-ray changes of advanced Madelung's deformity are well described, little quantitative information exists on the subtle, early changes of the deformity. This study investigated the threshold of 4 radiographic measurements that predict a diagnosis of Madelung's deformity by experienced hand surgeons. METHODS: Ulnar tilt, lunate subsidence, lunate fossa angle, and palmar carpal displacement were measured on x-rays of patients with Madelung's deformity. For each set of x-rays 4 opinions were available concerning a diagnosis of Madelung's deformity as based on the x-rays only. The 4 quantitative measurements were examined to determine a threshold value that predicts a unanimous diagnosis of Madelung's deformity. RESULTS: The thresholds for the diagnosis of Madelung's deformity are: ulnar tilt of 33 degrees or greater, lunate subsidence of 4 mm or more, lunate fossa angle of 40 degrees or greater, and palmar carpal displacement of 20 mm or more. When any one of these measurements equaled or exceeded this threshold value, the raters were unanimous in establishing a diagnosis of Madelung's deformity. CONCLUSIONS: Threshold values of ulnar tilt, lunate subsidence, lunate fossa angle, and palmar carpal displacement for the diagnosis of Madelung's deformity are determined. Lunate fossa angle may prove especially useful in the diagnosis of early Madelung's deformity.

Reconstruction of the type IIIA hypoplastic thumb.

The management of the hypoplastic thumb depends on the degree of bony malformation, soft tissue anomaly, and deficiencies. Type IIIA thumbs have thumb-index web-space narrowing, hypoplasia of the thenar musculature, metacarpophalangeal joint instability, and extrinsic tendon abnormalities. They also have a hypoplastic metacarpal with a stable carpometacarpal joint, differentiating them from type IIIB thumbs which have an unstable carpometacarpal joint due to partial metacarpal aplasia. Whereas type IIIB thumbs are best treated with ablation and index pollicization, type IIIA thumbs are amenable to reconstruction. Many techniques have been described for correction of the variety of deformities found in theses thumbs. The purpose of this article is to present our preferred technique for comprehensive reconstruction of type IIIA thumbs.

Distraction lengthening of the ulna in children with radial longitudinal deficiency.

PURPOSE: Children with radial longitudinal deficiency have very short forearms. The Ilizarov method of distraction osteogenesis has been used to increase extremity length, but results differ with the underlying condition and the limb being lengthened. The purpose of this study is to examine retrospectively the outcomes of Ilizarov lengthening of the ulna in children with radial longitudinal deficiency. METHODS: Nine children with radial longitudinal deficiency had 13 ulnar lengthenings using the Ilizarov method; 8 with unilateral deficiency had 9 lengthenings to improve appearance, and 1 child with bilateral radial longitudinal deficiency had 4 lengthenings to improve function. All had previous wrist centralization surgery, and all but 1 had a carpal osteotomy at the time of lengthening to reduce residual wrist angulation. RESULTS: The average gain for each lengthening was 4.4 cm (range 1.8-8.0 cm) with an average lengthening index of 9 weeks per cm (range 4-24 weeks per cm). All patients at each lengthening experienced at least 1 pin site infection that required antibiotic treatment. Other complications included delayed union requiring internal fixation and bone grafting in 3 lengthenings and recurrence of radial deviation requiring shortening and wrist arthrodesis in 1 case. CONCLUSIONS: The Ilizarov technique is an effective method for lengthening the ulna in children with radial longitudinal deficiency. The process of lengthening is prolonged and arduous with frequent complications. In successful cases, however, patients are pleased with the function and appearance of their lengthened forearms.

Madelung's deformity: quantitative assessment of x-ray deformity.

PURPOSE: To evaluate 5 defined measurement techniques that are applicable to x-rays of Madelung's deformity: ulnar tilt, lunate subsidence, lunate fossa angle, palmar tilt, and palmar carpal displacement. The measurements rely on the longitudinal axis of the ulna and the carpal bones to determine drawing lines and avoid the distorted distal radius and its deformed lunate fossa. The reliability and reproducibility of the measurements is determined. METHODS: Forty-eight sets of posteroanterior and lateral x-ray views of the wrist of subjects with the clinical diagnosis of Madelung's deformity were measured by 4 raters. Each rater made the 5 defined measurements on each pair of x-rays. Pairs of raters were compared for reliability using the Pearson correlation coefficient and Lin's concordance correlation coefficient. Two raters repeated the 4 reliable measurements a minimum of 6 months after the first measurements. Each rater's results were compared for reproducibility using Lin's concordance correlation coefficient. RESULTS: Ulnar tilt and lunate subsidence have excellent reliability and reproducibility. Palmar carpal displacement has acceptable reliability and reproducibility. Lunate fossa angle has borderline reliability but excellent reproducibility. Palmar tilt has poor reliability. CONCLUSIONS: Ulnar tilt, lunate subsidence, and palmar carpal displacement, as defined, are considered reliable and reproducible measurements for quantifying the severity of Madelung's deformity on x-rays. Lunate fossa angle is not sufficiently reliable for comparing preoperative and postoperative wrists but may prove useful in establishing an early diagnosis. Palmar tilt is not measured reliably on a lateral x-ray because of the superimposition of multiple structures on a lateral x-ray and the absence of the volar part of the lunate fossa in patients with severe Madelung's deformity. Advanced imaging techniques are needed to delineate the deformity of the distal radius in a lateral projection.

The association of radial deficiency with thumb hypoplasia.

BACKGROUND: Congenital longitudinal deficiencies of the radius and thumb are known to be associated with one another; however, the details of their relationship are unknown. The purpose of this study was to determine whether increased severity of radial deficiencies is associated with increased severity of thumb deficiencies and to review the relationship between radial deficiency and reconstructibility of a hypoplastic thumb. METHODS: Radiographs and charts of 227 affected upper extremities of 139 patients with radial longitudinal deficiency were reviewed. The associated thumb deficiency was classified according to a modification of the Blauth and Schneider-Sickert scheme and the radial deficiency was classified according to a modification of the Bayne and Klug criteria for 191 extremities of 119 patients. RESULTS: The severity of the thumb deficiency was directly proportional to the severity of the radial deficiency (p < 0.0001). Half of the extremities had either a thumb deficiency or thumb and carpal deficiencies without radial deficiency. Two-thirds (sixty-three) of the ninety-five limbs with a normal radius had a thumb that could be surgically reconstructed. Seventy-one (91%) of seventy-eight extremities with a thumb amenable to surgical reconstruction had a radius that did not require surgical reconstruction. All extremities with a radial and/or carpal deficiency had a thumb deficiency. Forty-eight (94%) of fifty-one extremities with complete absence of the radius had a thumb that was not reconstructible. CONCLUSIONS: This study supports the growing body of evidence that the components of radial longitudinal deficiency represent a progressive spectrum of upper extremity abnormalities, and a distal progression of severity, with distal structures likely to be more involved than proximal structures.