Any child with congenital joint contractures in two or more limbs can be classified as having arthrogryposis multiplex congenita (AMC) ; the term does not specify any certain cause for the contractures. Arthrogryposis can result from environmental or genetic causes but is most often idiopathic. Amyoplasia is an idiopathic disorder with a wide range of levels of severity and anatomic involvement ( Figure 39.1 ). Distal arthrogryposes (DAs) are genetic disorders with 11 discrete patterns, each with variable penetrance ( Figures 39.2 to 39.4 , Table 39.1 ). The most common DAs are types 1, 2A, and 2B (DA1, DA2A, and DA2B). Arthrogryposis can also result from myriad disorders that compromise the central or peripheral nervous system or the musculature; currently, over 300 types have been identified.
| Distal Arthrogryposis Types | Other Name(s) | Label | Characteristic Findings |
|---|---|---|---|
| Distal arthrogryposis type 1 | Common or typical | DA1 | Camptodactyly, clasped thumb, clubfoot |
| Distal arthrogryposis type 2A | Freeman-Sheldon syndrome | DA2A | Whistling face, camptodactyly, clasped thumb, clubfoot, scoliosis |
| Distal arthrogryposis type 2B | Sheldon-Hall syndrome | DA2B | Prominent nasolabial folds, down-slanting palpebral fissures, small mouth, camptodactyly, clasped thumb, clubfoot |
| Distal arthrogryposis type 3 | Gordon syndrome | DA3 | Short stature, cleft palate |
| Distal arthrogryposis type 4 | Scoliosis | DA4 | Scoliosis, camptodactyly |
| Distal arthrogryposis type 5 | Ophthalmoplegia, ptosis | DA5 | Ptosis, strabismus, restrictive lung disease |
| Distal arthrogryposis type 6 | Sensorineural hearing loss | DA6 | Hearing loss, camptodactyly |
| Distal arthrogryposis type 7 | Trismus-pseudocamptodactyly | DA7 | Trismus, pseudocamptodactyly, short stature |
| Distal arthrogryposis type 8 | Autosomal dominant multiple pterygium syndrome, Escobar syndrome | DA8 | Multiple pterygia, camptodactyly, scoliosis, ptosis, down-slanting palpebral fissures |
| Distal arthrogryposis type 9 | Beals syndrome (congenital contractural arachnodactyly) | DA9 | Camptodactyly, arachnodactyly, kinked upper earlobe, tall stature |
| Distal arthrogryposis type 10 | Congenital plantar contractures | DA10 | Plantar contractures |
Although the cause of amyoplasia is unknown, the clinical findings result from a localized or generalized neuromuscular system underdevelopment. Muscles are either absent or hypoplastic, often replaced by fibrofatty tissue. Tendons and overlying fascia are often preserved even when no muscle is present, leading to tethering at the joints. It is not clear whether the primary insult is at the central nervous system (motor cortex), the peripheral nervous system (anterior horn cells), or the target organ (muscles), or a combination of the three, because aplasia or hypoplasia of any of these systems alone in utero would result in concomitant loss of the other systems. Maternal bicornuate uterus and oligohydramnios have been historically thought to increase the risk of amyoplasia, yet recent studies have not found such a link.
Children with amyoplasia have a characteristic appearance with high cheeks and button noses and “stork bite” hemangiomas over the occiput and the bridge of the nose. Interestingly, there are a few identical twins in our practice with indistinguishable facial features, yet only one displays clinical signs and symptoms of amyoplasia. The hemangiomas are usually flat and small ( Figure 39.5 ) but can be protuberant and even extend through the skull into the cranium. Even though the lesions are benign and most resolve or diminish over time, raised lesions should be imaged to evaluate for intracranial extension. Despite or perhaps as a result of diminution of the motor cortex, children tend to have average to above average intelligence.
Preoperative Evaluation
History
Most children with arthrogryposis have no other medical conditions. Some, however, may have respiratory and gastrointestinal system involvement. A small percentage of children will have bowel atresia, abdominal wall defects, or gastroschisis. Approximately the same number will require mechanical ventilation at birth; they can typically be weaned to a tracheostomy and supplemental oxygen by their second or third year. Terminal limb deficits are more common in amyoplasia patients than in the general population. The family history is usually positive in DA and in other inheritable neuromuscular conditions, but it is otherwise negative. Quite a few children are adopted because their biologic parent is unable or unwilling to care for them, and the family history is therefore unavailable. The history should gauge the depth and resilience of the family support structure and the resources available.
Physical Examination
Building trust is critical to coaxing a meaningful examination from any child but doubly so for children with arthrogryposis, most of whom have already been traumatized by extensive medical interventions before ever seeing the upper extremity specialist. Begin with a global assessment of the child’s cognitive, social, and physical abilities. Some children are quite affected, requiring feeding tubes and mechanical ventilation. A thorough intake worksheet can help to obtain a more complete picture of the child’s needs ( Figure 39.6 ). All of the joints of the upper limb should be examined for both active and passive motion. Watching the child play with a variety of differently shaped and sized toys is an effective way of judging the child’s function. If possible, observe how the child eats finger foods or drinks from a bottle. There is no substitute for spending a few minutes playing with the child to gain a good understanding of who the child is as a person and what the child requires as a patient.
A more methodical examination of the upper limbs, when possible and age appropriate, proceeds from the shoulder to the fingertips. For the child who is unable or unwilling to respond to commands, having the child reach for toys and stickers followed by object manipulation may be the only way to examine the child. Assess every joint bilaterally in both active and passive motion as well as in the resting position. Internal rotation and adduction contractures of the shoulder are common; children with more than 90 degrees of active abduction and active external rotation past neutral rarely require any intervention about the shoulder.
Elbow flexion and/or extension contractures are also common and often suggest that there are underlying elbow flexors and extensors. The triceps is most often preserved and the elbow flexors are deficient, resulting in the more common elbow extension contractures. Occasionally, the triceps is weak or absent, causing an elbow flexion contracture. Finding the axis of rotation of the elbow in a child with less than 30 degrees of passive elbow flexion can be extremely difficult. Although historically the forearm has been thought to be in pronation in the majority of these children, most often the forearm is in neutral to slight pronation. The illusion of a pronation contracture is created by the internal rotation contracture of the shoulder combined with an extended elbow.
In patients with DA, the wrist is often in extension. Patients with amyoplasia typically have fixed wrist flexion contractures (see Figure 39.1 ). In the absence of active wrist extensors, some children will use the viable extensor digitorum communis (EDC) tendons to extend the wrist. This results in active extension to just shy of neutral but with concomitant metacarpophalangeal (MP) joints.
Hand function is highly variable, with intrinsic thumb flexion usually preserved even in the absence of other digital motion. There are several different patterns of hand deformities, some more commonly seen in specific AMC subtypes ( Table 39.2 ).
| Classification | JOINT POSITION | |
|---|---|---|
| CMC | MCP | |
| Type 1 | Extended | Flexed |
| Type 2 | Flexed | Extended |
| Type 3 | Flexed | Flexed |
* Subtype A is passively correctable, and subtype B is not correctable.
Children with arthrogryposis often have lower limb involvement as well. A thorough examination of the lower limbs should be carried out by a pediatric orthopedic surgeon familiar with this disorder. The state of current and potential future ambulatory status is critical to the overall treatment strategy.
Children with arthrogryposis will typically visit the operating room several times for spine, upper extremity, and/or lower extremity correction before the age at which they become good candidates for muscle/tendon transfers (usually 6 years old or older). If the child is undergoing any procedures requiring sedation, an examination under anesthesia can be performed at the same time to determine the true extent of contractures. Percutaneous needle stimulation of individual muscles can be used to determine the suitability of the pectoralis major, latissimus dorsi, and gracilis for muscle transfer.
Diagnostic Imaging
Routine radiographs are unnecessary for patients with arthrogryposis. Some experts advocate lateral finger radiographs to evaluate phalangeal condyle hypoplasia in cases of camptodactyly. Neither computed tomography nor magnetic resonance imaging is necessary for the diagnosis or treatment of AMC. Electrodiagnostic studies are rarely necessary other than in evaluating specific neurogenic contracture syndromes. Muscle biopsy rarely yields useful information unless a specific, unusual diagnosis is being pursued.
Pertinent Anatomy
Arthrogryposis affects the entire musculoskeletal system. Children with arthrogryposis have absent or hypotrophic muscles but may retain the associated tendons and overlying fascia. As the child grows, these noncontractile tissues can tether the joints, which may lead to joint contractures. Because the bones do not have the normal load of muscle activity or weight bearing, they may be severely osteopenic. Cortices in these children tend to be quite thick, but the bones are of small diameter and the medullary canal is nearly absent. The motor and mixed nerves are also small in caliber compared with those in other children of the same size. With thin bones and a hypoplastic musculature, the subcutaneous fat encompasses a larger than expected percentage of the bulk of the arms.
Historical Review
A historical review of milestones in the treatment of AMC is shown in Table 39.3 .
| Date | Article | Comments |
|---|---|---|
| 1841 | Otto AW: Monstrum humanum extremitatibus incurvatus: monstrorum sexcentrorum descriptio anatomica in Vratislaviae Museum [English translation], Clin Orthop Relat Res 194:44-53, 1985 | “A human monster with inwardly curved extremities” |
| 1897 | Schanz A: Ein Fall von multiplen kongenitalen Kontracturen, Z Orthop Chir 5:9-15, 1897 | “Multiple congenital contractures” |
| 1905 | Rosencranz E: Ueber kongenitale Kontracturen der oberen Extremitaten, Z Orthop Chir 14:52, 1905 | “Arthrogryposis” |
| 1923 | Stern WG: Athrogryposis multiplex congenita, JAMA 81:1507, 1923 | “Arthrogryposis multiplex congenita” |
| 1925 | Lewin P: Arthrogryposis multiplex congenita, J Bone Joint Surg Am 7:630-636, 1925 | “Attempts to produce movable joints are not highly successful” |
| 1952 | Hillman JW, Johnson JTH: Arthrogryposis multiplex congenita in twins, J Bone Joint Surg Am 34:211-214, 1952 | Reported two cases of monozygotic twins where only one of the twins was affected; concluded that the cause was not genetic |
| 1958 | Meade NG, Lithgow WC, Sweeney HJ: Arthrogryposis multiplex congenita, J Bone Joint Surg Am 40:1285-1309, 1958 | Refuted preexisting idea that children with arthrogryposis were of below-normal intelligence; in their series of 40 patients, 29 had upper extremity involvement |
| 1970 | Carroll RE, Hill NA: A study of fifteen patients with paralytic lesions and arthrogryposis, J Bone Joint Surg Am 52(2):239-244, 1970 | Unpredictable results with triceps to biceps transfers in eight patients with arthrogryposis |
| 1973 | Williams PF: The elbow in arthrogryposis, J Bone Joint Surg Br 55(4):834-840, 1973 | Achieved an average of 65 degrees of elbow motion in four patients after tricepsplasty (posterior elbow release) |
| 1984 | Yonenobu K, Tada K, Swanson AB: Arthrogryposis of the hand, J Pediatr Orthop 4:599-603, 1984 | Showed improvement in posture and function with soft tissue and bony procedures to correct thumb-in-palm deformities and finger contractures/ulnar drift |
| 1985 | Bennett JB, Hansen PE, Granberry WM, Cain TE: Surgical management of arthrogryposis in the upper extremity, J Pediatr Orthop 5:281-286, 1985 | Created surgical treatment algorithm for the upper extremity that serves as the basis for current treatment paradigm |
| 1985 | Palmer PM, MacEwen GD, Bowen JR, Mathews PA: Passive motion therapy for infants with arthrogryposis, Clin Orthop Relat Res 194:54-59, 1985 | Early passive stretching and serial splinting improved motion and function |
Surgical Procedures
The goal of any treatment plan for a child with arthrogryposis is to maximize functional independence for that child. For the lower extremities, the goals are ambulation and sitting. Traditionally, ambulation has trumped all other treatment goals. In many centers, the lack of expertise and familiarity with upper limb surgery relegates upper limb function to an afterthought. This dismissal is a disservice to these children and to the adults who care for them. Basic upper limb function is just as important to the well-being of these children as ambulation. For the upper extremity, the primary goals are to have “one hand to eat and one to wipe.” They can be the same hand. The rate-limiting step in optimizing the child’s independence is always finger and thumb motion. Independent self-feeding requires at least some hand function. The child must be able to acquire the food, grip it firmly enough to bring it to the mouth, and release it. Beyond that, the wrist and the elbow combined must have enough extension to reach the plate or the table and sufficient flexion to allow the hand to reach the mouth. Forearm and shoulder rotation need to allow the hand to face the plate and then the mouth. In very impaired children, independent feeding may be an unrealistic goal. A skilled therapist and the use of adaptive equipment may achieve some independence ( Figure 39.7 ).
Perineal care can be performed through the legs or around the back. Both require sufficient hand function to hold toilet paper firmly. Children who wipe their buttocks through the legs require wrist flexion, elbow extension, and shoulder internal rotation. Children who wipe their buttocks around the back require forearm supination, elbow extension, and shoulder extension.
The next priorities on the functional ladder are bathing and dressing, followed by food preparation, driving, and other activities of daily living. Recreational activities and sports participation may be achievable in mildly affected children.
Humeral External Rotation Osteotomy
Indications
Children with arthrogryposis typically present with internal rotation and adduction contractures. Elbow extension contractures can create the appearance of a pronation contracture, but most often the posture results from internal rotation at the shoulder with the forearm most often in neutral. The deltoid, rotator cuff, pectoralis, latissimus dorsi, and periscapular muscles may be weak or absent. Although rarely responsive to passive stretching, a course of therapy is recommended. Capsular releases have not been effective. Internal rotation contractures are best treated with a humeral external rotation osteotomy. The medial approach requires visualization and retraction of the median and ulnar nerves but is more cosmetic and provides a better bony surface for plate application than the deltopectoral approach. For the child with a severe elbow extension contracture, distinguishing between an internal rotation contracture at the elbow and a pronation contracture at the forearm can be difficult. For these children, we will perform an elbow release first, followed by a humeral rotational osteotomy if needed. We rarely perform bilateral procedures in these children because the margin of error is so small for losing midline function.
Contraindications
Relative contraindications include (1) insufficient internal rotation for perineal care, (2) older age with established crossover grasp ( Figure 39.8 ), and (3) absence of pectoralis function. Children who lack pectoralis function but retain triceps function will use an obligatory crossover grasp pattern that requires internal rotation.
Preoperative Planning
Plates and screws of the appropriate size are required and are often a size smaller than what would be expected for a humerus of an unaffected child of the same age.
Technique
Place the patient supine on a standard operating room table with a hand table. Regional anesthesia may be used to control postoperative pain along with general anesthesia. If a tourniquet is used, the Hemaclear tourniquet (Hemaclear, OHK Medical Devices, Grandville, MI) allows sufficient proximal exposure. If a tourniquet is not used, inject bupivacaine with epinephrine subcutaneously along the length of the intended incision. Prepare and drape the arm to the axilla.
Incise the skin and raise full-thickness subcutaneous flaps while preserving the medial brachial and antebrachial cutaneous nerves, as well as the basilic vein. Incise the fascia between the median and ulnar nerves along the intermuscular septum. Regular palpation is required to feel the humerus because muscle planes may not be clearly delineated. Using a periosteal elevator, expose the humerus extraperiosteally to a length sufficient to place a plate. Plates of 2.4 mm to 3.5 mm are used for this operation and should be appropriate for the size of the bone. Gently precontour the plate so as to provide compression on the far side of the bone.
Apply the plate provisionally to the proximal osteotomy fragment as far anterior as the soft tissues will allow. Remove the plate. Split the periosteum longitudinally and apply Hohmann retractors to protect the surrounding neurovascular structures. Perform a transverse osteotomy using a reciprocating saw while preserving the periosteal sleeve. Reapply the plate to the proximal fragment. Place a fracture reduction clamp around the distal fragment and the plate. Externally rotate the arm to the desired position of between neutral and 15 degrees of internal rotation. Provisionally clamp the distal humeral fragment to the plate and reassess the rotation of the arm. Sufficient internal rotation should be preserved to allow for midline function, such as perineal care. Fix the plate to the distal fragment with a single screw and reassess one more time ( Figure 39.9, A ). If the position of the arm is optimized, confirm the screw lengths and plate position using fluoroscopy (see Figure 39.9, B ).
Close the subcutaneous layer and the skin in standard fashion. Place the elbow in 90 degrees of flexion and apply a sterile dressing followed by a long-arm splint with a side bar to prevent elbow extension. If the fixation was felt to be tenuous or the child is very active, a triangular wedge can be used to place the arm in a “gunslinger position” ( Figure 39.10 ).
Author’s Preferred Method of Treatment
Alternative approaches to a humeral osteotomy include the posterior and anterolateral approaches. The advantages of the medial approach are primarily cosmetic, because the majority of children keep the shoulders adducted and conceal the scar. We are currently evaluating concomitant elbow release and humeral rotational osteotomy, but early results are not promising. For the time being, it is better to perform the elbow release at a separate time.
- •
Make sure that the patient has internal rotation to spare before considering an external rotation osteotomy.
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Make sure that the internal rotation/pronation posture is truly coming from the shoulder and not from the forearm.
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If there is less than 30 degrees of elbow flexion, consider an elbow release prior to humeral osteotomy.
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For the medial approach, identify and gently retract the ulnar and median nerves.
- •
Apply the plate proximally first to simplify the procedure before making the osteotomy.
- •
Protect the radial nerve with Hohmann retractors deep to the periosteum while making the osteotomy.
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Gently precontour the plate to provide far-side compression.
- •
Test the amount of rotation several times before final fixation to ensure an optimal position.
- •
Use a gunslinger brace if the child is prone to falling or if the fixation is suboptimal.
- •
Use a fracture brace after 4 weeks if the osteotomy has not healed.
- •
Beware of long-term periimplant fractures.
Postoperative Management and Expectations
Expected Outcomes.
Union is typically achieved between 4 and 6 weeks, although occasionally it may take up to 10 weeks. Remove the splint 4 weeks after surgery and outfit the child with a fracture orthosis ( Figure 39.11 ) if union has not been achieved. Begin a passive range-of-motion protocol while maintaining the orthosis at all other times until union. Patients can expect improvements in hand-to-mouth and hand-to-neck activities if there is adequate elbow and shoulder motion. Bimanual tasks are also more easily performed because the hands should face each other after the osteotomy. Bilateral osteotomies may be required, but staging them is preferred.
Complications.
Overrotation or underrotation is the most common complication. Typically, younger children will correct for overrotation but will not correct for underrotation. Older children, particularly those with minimal shoulder rotation, have a lesser margin for error. Neurapraxia of any of the major nerves can also occur, but more considerable nerve injuries are rare. If nerve function has not recovered after 2 to 3 months, electrodiagnostic studies are warranted. Infections and nonunions are rare, but delayed unions do occur, especially if there is a gap at the osteotomy site or if the periosteum was stripped. Fractures at the ends of the plate are an ongoing concern.
Elbow Extension Contracture Release
Indications
Most children with arthrogryposis lack adequate elbow flexion to oppose the working triceps, leading to extension contractures. Some children have active elbow flexion but no extension, leading to flexion contractures; pterygium is common in this group. Other children have only a jog of passive motion at the elbow. If the child cannot flex the elbow more than 30 degrees, the true axis of rotation of the elbow joint can be difficult to determine. Caretakers and health care professionals are discouraged from performing passive range of motion of these elbows because inadvertent collateral ligament damage or physeal injuries can result.
Impressive gains in elbow range of motion can be made in some children who can flex the elbow beyond 30 degrees. Progressive static splinting, as can be accomplished with an hourglass splint ( Figure 39.12 ), will augment and preserve the gains made with therapy. Passive hand-to-mouth motion can allow the child to perform feeding and grooming tasks by pushing the arm against the knee or other arm, a desk, or a table, or by abducting the shoulder and allowing gravity to flex the elbow ( Figure 39.13 ).
Indications for surgical release include less than 30 degrees of elbow flexion by 12 to 18 months of age and failure to achieve sufficient elbow flexion for self-feeding at any age.
Elbow flexion contractures are even more difficult to treat. The paradigm is the same initially, with passive range-of-motion exercises and splinting. Most children with elbow flexion contractures lack triceps function and some also lack active flexion. A pterygium across the antecubital fossa commonly accompanies elbow flexion contractures ( Figure 39.14 ) and is a harbinger of a more recalcitrant problem. There is as yet no reliable surgical or nonsurgical technique to resolve these contractures.
Contraindications
Relative contraindications include (1) having a contralateral side elbow flexion contracture that prohibits perineal care and (2) a requirement of triceps function for ambulation.
Preoperative Planning
No specialized equipment is required.
Technique
Place the patient supine on a standard operating room table without a hand table. Prepare and drape the arm to the axilla. If a tourniquet is being used, a Hemaclear tourniquet (Hemaclear, OHK Medical Devices, Grandville, MI) allows sufficient proximal exposure. If a tourniquet is not being used, inject bupivacaine with epinephrine subcutaneously the length of the intended incision.
Define the anatomic landmarks of the elbow, beginning with the olecranon, by following the subcutaneous border of the ulna in a proximal direction. Confirm the position of the olecranon by identifying the medial and lateral epicondyles. If there is any doubt, fluoroscopic images are obtained.
The incision should run the entire length of the triceps tendon, at least midway up the brachium, curving ulnar to the olecranon. Raise full-thickness subcutaneous flaps both medially and laterally just past the level of the epicondyles. The ulnar nerve is identified just proximal to the cubital tunnel beneath a thick fasciotendinous band of the triceps that inserts onto the medial epicondyle and the ulnar side of the olecranon. Transpose the ulnar nerve anteriorly into a subcutaneous pocket, and suture the subcutaneous fat to the anterior aspect of the medial epicondyle to close the pocket ( Figure 39.15, A ). Make sure that the medial antebrachial cutaneous nerve and its branches are not sutured in the fat. After transposition, confirm that the ulnar nerve is not kinked or compressed anywhere along its new course.
