Radial Aplasia and Distraction Lengthening
Radial Deficiency and the Role of Distraction Lengthening
Advances in Orthopaedic
Surgery, Copyright ~ 1992 Data Trace Medical
Publishers, Inc.
Vol. 16, No. 3. Printed in U.S.A.
0738-2278/$3.00/92
William P. Cooney, M.D. and Mark T. Dahl, M.D.
Mayo Clinic, Rochester, Minnesota and Shriners Hospital for Crippled Children, Minneapolis, Minnesota
Radial deficiency represents a congenitally acquired absence of the preaxial limb-bud of the upper extremity. The degree of radial aplasia is related to the degree and time of insult to the developing fetus. The clinical presentation can be mild (hypoplasia of radius with affected thumb); moderate (deficient thumb and partial absence of the radius); or severe (absence of thumb and entire radius). Previous treatment programs concentrated on preventative splinting, delayed centralization of the radius, and later thumb reconstruction by pollicization of the index finger. Centralization of the radius, a technique by which the hand-wrist unit is positioned on the end of the ulnar epiphysis, is the most commonly recommended treatment for radial deficiency (radial club hand deformity). First described by Sayre (1893) it consisted of stabilizing the wrist by placing the sharpened end of the distal ulna into a notch created in the carpus; the ulna physis (growth plate) was destroyed. The procedure was modified by Carroll (1966), Lidge (1969), and Bora et al. (1981) so that the distal ulna physis was preserved and a larger notch or seat was created in the carpus. Recent publications (Bayne, 1988; Lamb, 1977; Manske et al.. 1981) confirmed this technique as the treatment of choice for radial aplasia.
This logical approach to severe radial angulation and the associated deformities of the wrist was not always successful. Recurrence of the radial angulation, lack of wrist extension, and spontaneous fusion of the ulna physis have been noted with unsatisfactory results in 25-35% of series reported. Recurrence was particularly noted in Bayne type III (partial radial agenesis) and type IV (complete radial agenesis), which are unfortunately the most common presentations (Table 1). Problems of recurrence in fact led Buck-Gramcko (1971) to describe a procedure called radialization in which the carpus is overcorrected on the distal ulna. Tendon transfer of the extensor carpi radialis and flexor carpi radialis (when present) to the ulna side of the wrist was recommended to convert deforming radial forces into rebalancing ulnar strengths. Watson et al. (1984) added early release of the radial anlage with a two-incision approach but without carpal bone excision in an effort to address some of the problems of recurrence.
| Table 1. Radial aplasia classification |
| Type l: Short radius: delayed appearance, thumb aplasia |
| Type Il: Hypoplastic radius: small short radius; decreased growth rate |
| Type llI: Partial absence radius: hand radial angulation; ulna hypertrophy |
| Type IV: Total absence of radius: severe radial angulation |
A new concept of early carpal
distraction has been developed as a result of continued problems
of recurrence and deficient limb growth. In this new concept,
early carpal distraction is performed prior to centralization
of the radius. This idea was first suggested by Kessler (1989)
as the initial step in rebalancing the wrist-hand unit on the
forearm. For this technique, the distraction apparatus (Kessler
frame) is applied not for bone lengthening as was first described
but for soft-tissue distraction. In the presence of tight contracted
radial tissues (radial anlage), the principle of gradual distraction
of the radial deviated hand-wrist unit is performed. After the
soft tissues are stretched and lengthened at a slow rate of 0.5-1
mm/day (a rate which simulates intrauterine growth), reduction
of the carpus can be atraumatically performed and rebalancing
tendon transfers considered without the force and technical difficulties
of a one-stage centralization procedure. This report describes
our experience with two different concepts in the treatment of
radial dysplasia with primary application of external distraction
frames. It will relate the use of the Kessler apparatus for the
young patient (<3 years) and the Ilizarov frame in older patients
(>5 years). Principles of bone and soft-tissue distraction
as essential elements in the treatment pro grams are emphasized.
In younger patients distraction will be the
first stage of soft-tissue lengthening and in the older patients,
distraction will be in the late stages for combined soft-tissue,
bone, and angular deformity corrections.
METHODS AND MATERIALS
Seven patients (ages 15 months to 12 years) from a series of 17 patients with radial agenesis had distraction lengthening for correction of radial aplasia. In three young patients, the Kessler frame was applied across the lower third of the forearm and distal pins were placed either in the metacarpals or the carpal bone. The primary goal was carpal alignment followed by second-stage centralization and third-stage pollicization. At the time of centralization, tendon transfers or repositioning of tendons present (i.e., the extensor carpi radialis and ulnaris) were performed in all three patients in an effort to provide soft-tissue balance and avoid recurrence. We excised the radial anlage in two of three patients with severe deformity. K-wires were used to hold the carpus aligned in one patient and an intramedullary rod was inserted through the long finger metacarpal, capitate, and distal ulna in the other two patients. One patient had lengthening through the diaphysis of the ulna with the Kessler frame, providing length for the forearm and correction of angulation deformity.
In the older patients (ages 10 to 14 years), the Ilizarov frame was the primary method for correction of the limb length and/or angulation deformity (Table 2). The latter provided both 1) repositioning (after lengthening) of the carpus in patients that had recurrence of radial angulation (palmer-radial) and 2) ulna osteotomy and lengthening, which corrected forearm bowing. Two- or three-ring Ilizarov constructs were used in these two patients. By design, both patients were older with sufficient limb size to accept the Ilizarov system. Smaller frames of light-weight polycarbons are in planning stages, which would extend three-dimensional concepts to younger patients.
| Table 2. Mayo Series radial aplasia |
| N= 17 |
| Male 12 |
| Female 5 |
| Age 1-4 yrs Kessler |
| Age 5-14 yrs Ilizarov |
| Radial lengthening = 2 |
| Ulnar lengthening = 5 |
| Centralization alone = 12 |
| Centralization with lengthening = 4 |
The third application of external frames involved single bone lengthening for radial dysgenesis or limb shortness from primary disease processes such as osteochondromata or Madelung's deformity. We applied a hybrid frame for isolated bone lengthening in three patients. The hybrid consists of proximal full-ring Ilizarov construct with full transfixion wires and distal half-rings from Ace-Colles fixateur with 2-mm threaded half-pins. Selective radius or ulna lengthening can be achieved using this hybrid system.
Kessler Frame Technique
The angulation of the radius is measured by careful radiograph assessment including biplanar studies. The correction of angulation of the radius and the length of distraction needed to accomplish the realignment of the hand-carpal unit on the distal ulna is measured. The goal is atraumatic axial alignment between the ulna and the hand. Skeletal limb lengthening is not the purpose of the procedure at this stage of treatment. At the time of surgery, passive correction of the radial angulation is achieved and the placement of the transfixing pins is determined. Care is taken to avoid soft-tissue planes of danger to neurovascular structures. In general, the K wires (threaded) are placed parallel to each other in the proximal end of the ulna and in the metaphyseal region of the finger metacarpals. It is essential to place the K-wires as close to perpendicular to the anticipated longitudinal axis of the forearm-hand to maximize correction. The distraction apparatusis is then applied to accommodate the position of the K-wires. Preplanning of placement of the frame with respect to the elbow and wrist joint is necessary so that the frame can provide angulation correction and not limit motion. Gradual distraction is started on the second or third postoperative day after soft-tissue swelling has subsided. If the entire radius is absent, primary distraction of the carpus for realignment with the ulna is performed without surgical release of the anlage. The rate of correction of angulation and ulna length is at 0.5-1.0 mm/day, with half a turn of the thumb screw twice daily. Lengthening is withheld if the process is painful and restarted at 24 hours. There is no regenerate to judge time of lenghtening, therefore it is purely the appearance and alignment of the hand and forearm that determines the period of lengthening. If there is only partial radial absence (type 111), excision of the radial anlage is recommended prior to starting distraction. Otherwise the anlage may retard the lengthening process and cause pain during repositioning of the hand.
Under gradual distraction both angulation and length are corrected. The amount of correction of angulation is related to differential turning of the radial ulnar thumb screw. Each case must be individualized and the amount and rate of lengthening related to patient tolerances and comfort.
With a rate of 0.5-1.0 mm/day, an inch (2.54 cm) of lengthening would take between 2 and 4 weeks. To correct the typical radial angulation, the radial lengthening rod thumb screw is turned twice the rate of the ulnar rod thumb screw. Once the corrected length is obtained, the central alignment is main tained by a longitudinal Steinman pin or Rush rod which is left in place 3 to 6 months. Importantly, resection of carpal bone or a forceful reduction of the carpus on the distal ulna has not been necessary.
llizarov Technique
The Ilizarov method is a recently developed and applied three-dimensional distraction-correctional device that has great value in the upper extremity. To date, it has been used in older patients to: 1) lengthen the radius alone (stage I or II, radial aplasia); 2) lengthen the ulna for late radial aplasia (stage III or IV); or 3) lengthen the ulna for other developmental or congenitally acquired growth disturbances. In the two cases of radial dysplasia described, the carpus had subluxated palmer and radial after a previous centralization I procedure. Damage to ulnar physeal growth was also evident. In these cases, two-level correction of angulation, forearm length, and carpal alignment was performed by the llizarov technique. The procedure of lengthening with the llizarov technique requires careful preoperative planning. Extremity scanograms are helpful to determine proper limb alignment and to exactly measure limb length differences. Paper trace cut-outs can be helpful in planning the area of lengthening, site of corrective osteotomy, circular ring placement, and position of the distracting bars. The proximal ring, for example, can not be too close to the antecubital fossa and the middle ring must be not only distal to the osteotomy site, but have a hinge for improving angular deformity. In general, the proximal ring construct is placed first with tension K-wires placed across the ulna metaphysis. An open ring may be necessary (open segment anteriorly toward the antecubital fossa) to avoid contact with the distal arm and susceptible median and radial nerves. The second ring construct is placed in the mid-third of the ulna. The K-wires are best pushed through the soft tissues to avoid neurovascular dam age at this level. Distraction between the proximal and middle rings is considered for ulna lengthening and correction of midshaft angulation deformity. The distal ring is placed across the base of the metacarpals and distal carpal row. If there is a need to correct carpal alignment (which is usual), it can be performed through the distal ring and midring with attention paid to both degree of carpal lengthening (stretch) and the needed improvement in radial angulation.
Hybrid Frame Construction
In young patients, it is usually not possible to apply the llizarov frame simply because the frame is too large, heavy, and not well designed to apply to a young, hypoplastic forearm. In these circumstances where we wish single bone or differential lengthening, we apply a hybrid system of full rings and half rings. The proximal ring can be an Ilizarov circular ring (with continuous wires); the middle or distal rings can be half rings (Ace-Colles type) and the distal rings can be a full or a half ring using either threaded half pins or transfixion K-wires depending upon the site of ring placement. Half pins (2.5 - 3.0 threaded pins) are preferred in the mid and distal pin placement sites. There are a number of adapted devices that can be assisted by utilization of the half pins. Lengthening of the radius (for Bayne stage I or II radial aplasia); lengthening of the ulna (for Bayne stage III or IV radial aplasia); and correction of osteochondromata of radius and ulna with forearm angulation; or Madelungs's deformity can be more easily and carefully performed with half pins rather than with transfixion K-wires or Bonnel central threaded transfixion pins. Careful preoperative planning on X-rays or drawing paper is essential to determine the best level of correction and placement of both pins and frame.
CASE STUDIES
Case 1 An 8-year-old boy presented with radial angulation
of the hand and wrist and a differential length between the right
and left upper extremities (Fig. 1B). There was earlier surgery
for the bilateral radial agenesis consisting of cen tralization
procedures (Fig. 1A). Without the needed tendon transfers, both
hands had moderate recurrence, but the right side involvement
was slightly worse and the most disabling to the patient. It was
8 cm shorter and had the carpus "falling off" the distal
end of the ulna.
A three-ring Ilizarov construct (Fig. 1C) was assembled preoperatively and placed around the ulna metaphysis proximally and the midsshaft (correcting for angulation) centrally, and about the hand metaphysis or through the distal carpal row distally. Proper location of the distracting bars, hinges, and pins is essential for a painless, effective distraction program. Preoperative planning is quite important. Distraction was begun at day 4 and continued each day at a rate of 1-1.5 mm/day until limb (Fig. 1D) and carpal (Fig. 1E) alignment were obtained. Mild contraction of the finger flexor tendons was counteracted by an orthoplast splint with traction outriggers. Elbow contraction (up to 45i) developed during the distraction process, but resolved to nearly full extension (<10i) with slow gentle traction using a hinged elbow splint (Figs. 1F, 1G) and physiotherapy. The entire period of immobilization was nearly 70 days with the bone regenerate first presenting at 40 days and then progressing to union by 2z months. In one older patient (age 14), the regenerate took quite a long time to appear and immobilization continued during that time period. We prefer 6 months of relative immobilization with splinting started about the 6th or 7th week. Overall improvement of limb length and carpal alignment can be achieved by these techniques (Fig. l H).
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Case 2 The second case is a 2-year-old girl with radial aplasia and multiple systemic congenital anomalies (VACTERL). The radius was entirely absent (Bayne type IV) (Fig. 2A). After open heart surgery, esophageal-tracheal fistula repair, and treatment of partial renal agenesis, she underwent cervical spine fusion for congenital torticollis. At the same time, first-stage carpal distraction was performed with the Kessler technique (Fig. 2B). Release of the radial anlage (Fig. 2C) and full distraction resulted in a centralized carpal-hand unit (Fig. 2D). Clinical function substantially improved, including bimanual ac tivities (Fig. 2E), such as reaching her mouth for self-feeding care.
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Case 3 A 5-year-old girl with a type III radial aplasia presented with a severe angulation deformity of the forearm. She had a centralization at an early age but with recurrence of deformity (Fig. 3A). Distraction lengthening of the ulna (Fig. 3B) with corrective osteotomy was performed using the Kessler frame (Fig. 3C). Distraction of 8 cm was achieved (Figs. 3D,E). The Kessler frame was well tolerated without pin tract or wound problems (Fig. 3F). The parents were able to perform the distraction lengthening at home. A fibular interposition bone graft was inserted with internal fixation Steinman pins (Fig. 3G) after maximal lengthening had been achieved. Part of the length deter mination was tolerance for the external frame and transfixion pins. The align ment of the hand-wrist unit and the forearm was overall improved but the extremity remained short in comparison with the normal, unaffected side (Fig. 3H). Premature closure of the ulna physis presumably from the centralization procedure at a young age was responsible for the inability of the affected forearm to keep up with growth.
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Case 4 This patient was an 8-year-old boy with ulnar club hand deformity (type 1 Riordan classification). The ulna was present with both a proximal and distal physis, but was quite short (Fig. 4A). There was an associated bowing of the radius and radial head dislocation. The presence of the proximal and distalphyses suggested that ulnar lengthening and radial corrective osteotomy should be considered. Ulnar lengthening was performed with the Olizarov technique (Fig. 4B) and the radius osteotomy was stabilized with crossed K wires. The ulna regenerate through a metaphyseal osteotomy healed primarily with a length increase of 7 cm and radial alignment was maintained (Fig. 4C). The radial head partially reduced as the ulna was lengthened.
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Case 5 A 10-year-old boy presented with ulnar deviation of the forearm and a family history of osteochondromata (Fig. SA, top and bottom). There was relatively normal limb growth except for the ulnar bowing of the forearm. Treatment consisted in excision of the osteochondroma and ulnar lengthening (Fig. SB, top and bottom). A corrective osteotomy of the radius was also performed. Union was achieved promptly of both radius and the ulaa regenerate. At 2 years, the radiographic and clinical appearance of the forearm was excellent without evidence of recurrence of deformity (Fig. SC).
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DISCUSSION
The current treatment for radial aplasia is centralization of the carpus on the distal ulna. In this article, several new concepts are presented which use this basic philosophy to create a stable hand-wrist unit (Table 3). As a one-step procedure (which is currently recommended), centralization alone can cause incomplete correction of angulation deformity, cause or contribute to pre mature closure of the ulna physis, and produce potential nerve and blood vessel trauma. The new concept of distraction lengthening (lengthening fol lowed by carpal centralization) is a more physiologic approach (Kessler, 1989). Bone and soft-tissue lengthening can be achieved simultaneously at a rate which simulates intrauterine growth, and dramatic improvements in alignment and length can result. Attention to soft-tissue corrective procedures such as Z-plasty release, ulnar relaxing skin incisions, or excision of redundant skin can easily be achieved, but may be unnecessary with early carpal distraction. Stretching of tight radial neurovascular and muscle-tendon units can occur gradually with compensation on the "loose" ulnar side of the wrist for the tight radial side deformity. Tendon transfer, often necessary to balance the extensor tendon forces, has been more easily performed after distraction and often we see some component of normal tendon and muscle fibers on the radial side to contain more function than initially anticipated.
| Table 3. Problem areas of radial aplasia | |
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| Loss of length | 1st stage distraction |
| Deformity type III bowing | Osseous + bone distraction |
| Deformity type IV | Soft-tissue distraction |
The concept of gradual lengthening of the upper extremity was
first suggested by Afaounove (Kessler, 1989) for the treatment
of a posttraumatic radial angulation deformity. Dreyfus (1977)
performed a correction of radial wrist, deviation after a case
of osteomyelitis by gradual distraction. Kessler (1989) appears
to be the first to have suggested distraction lengthening for
radial club hand deformity as a prelude to carpal centralization.
His technique emphasized lengthening of the soft tissues and not
the bone. Our experience parallels Kessler's in the young patient.
Several surgeons have reported the use of the llizarov device
for extremity lengthening, primarily in older children with limb
shortness. Dahl, however, pioneered the idea of a hybrid fixator
for the upper extremity that could be used in children of multiple
ages. With a proximal full ring and distal half rings, multiple
plane correction of length and angulation could be achieved. The
half frames were placed distally over the radius or ulna and half
pins were used to attach the frame to the underlying skeleton.
The smaller half rings provided versatility and a variety of options
for lengthening. Both bone and soft tissue could be stretched
to provide limb alignment without neurovascular compromise. In
radial agenesis, the hybrid frames could be used for either stage
I or 11 with single bone lengthening or the hybrid frames could
be applied for first-stage correction of the radial angulation
in stage 111 or IV. For late case presentations, frame innovations
could provide three-dimensional alignment of the bowed ulna, Iengthen
the limb, and reduce the carpus back to the distal ulna.
These new concepts are a step forward in more physiologic treatment programs for radial aplasia (or other causes of forearm length discrepancy). Softtissue lengthening prior to centralization; radial or ulnar lengthening for acquired or traumatic growth disturbance; or osseous lengthening for limb shortness can be considered with several frame designs as options. The Ilizarov system and its variants have great potential. The goals of extremity alignment correction of osseous length and physiologic stretch of soft tissues are now reality with application of these devices with minimal risk to growth centers or to local nerves and vessels.
SUGGESTED READING / REFERENCES
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Bora FW Jr, Osterman AL, Kaneda RR' et al. Radial club-hand deformity: Longterm followup. J Bone Joint Surg [Am] 1981;63-A:741-745.
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Sayre RH. A contribution to the study of club-hand. Trans Am Orthop Assoc 1893,6:208-216.
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I . J Hand Surg [Am] 1984;9A:541-547.