Pertinent Anatomy and Classifications
The upper limb develops early and rapidly during development, beginning at approximately 28 days after fertilization and completed by day 56. Development in three axes involves the apical ectodermal ridge, the zone of polarizing activity, and the dorsal ectoderm through a complex feedback mechanism, regulated by fibroblast growth factor, sonic hedgehog, and the wingless-type pathway. Disruption in any of these during development can lead to longitudinal, central, or transverse deficiencies.
The etiology of many of the hand differences we see clinically are not fully recognized. However, Ogino and colleagues induced radial and ulnar longitudinal deficiencies in a rat model by administering a chemotherapy agent at different points in fetal development of the upper limb. Interestingly, high rates of fetal demise occurred at a similar time point as the induction of ulnar longitudinal deficiencies, suggesting a mechanism for the 10:1 ratio in the incidence of radial-to-ulnar longitudinal deficiencies seen clinically. Transverse deficiencies have not been induced in an animal model, but are thought to be due to subclavian artery disruption during early development.
Radial longitudinal deficiency (RLD) is the most common upper limb longitudinal deficiency, with an incidence reported between 1:5000 and 1:100,000 live births and a 3:2 ratio of males to females. Bilateral cases present equivalently to unilateral cases; however, the right is more often affected than the left. Clinical presentation is greatly varied from mild shortening to complete absence of the radius and with, or without, thumb hypoplasia. In the classification system proposed by Swanson, RLD falls under IB1, failure of formation, longitudinal arrest, and radial ray. In the expanded Oberg–Manske–Tonkin classification system, RLD is classified as I.A.2.i if there is thumb hypoplasia and forearm involvement and I.B.2.i if there is thumb hypoplasia without forearm involvement.
Bayne and Klug initially classified RLD into four types. As understanding of the disease process evolved, this was expanded to include types 0/N for patients with a normal distal radius as well as type V, reflecting proximal involvement of the radius as seen with phocomelia ( Table 9.1 ). The thumb involvement in radial longitudinal deficiency was classified by Blauth into types I–V. Manske subsequently added subtypes IIIA and IIIB to reflect the stability of the carpometacarpal joint, which importantly helps drive our reconstructive algorithm. ( Table 9.2 ).
| Type | Thumb | Carpus | Distal Part of Radius | Proximal Part of Radius |
|---|---|---|---|---|
| N | Hypoplastic or absent | Normal | Normal | Normal |
| 0 | Hypoplastic or absent | Absence, hypoplasia, or coalition | Normal | Normal, radioulnar synostosis, or congenital dislocation of radial head |
| 1 | Hypoplastic or absent | Absence, hypoplasia, or coalition | >2 mm shorter than ulna | Normal, radioulnar synostosis, or congenital dislocation of radial head |
| 2 | Hypoplastic or absent | Absence, hypoplasia, or coalition | Hypoplasia | Hypoplasia |
| 3 | Hypoplastic or absent | Absence, hypoplasia, or coalition | Physis absent | Variable hypoplasia |
| 4 | Hypoplastic or absent | Absence, hypoplasia, or coalition | Absent | Absent |
| Feature | Type I | Type 2 | Type 3A | Type 3B | Type 4 | Type 5 |
|---|---|---|---|---|---|---|
| Thumb size | Normal or small | Normal or small | Small | Small | Very small | Absent |
| First web | Normal size and location | Distal and tight | Distal and tight | Distal and tight | APB, OP, FPB, and adductor absent | APB, OP, FPB, and adductor absent |
| Intrinsic muscles | APB and OP hypoplastic | APB and OP hypoplastic or absent | APB and OP absent or severely hypoplastic | APB and OP absent or severely hypoplastic | APB, OP, FPB, and adductor absent | APB, OP, FPB, and adductor absent |
| Extrinsic muscles | Normal | Normal or nearly normal | Abnormal: FPL and/or EPL absent or FPL–EPL connection or pollex abductus | Abnormal: FPL and/or EPL absent or FPL–EPL connection or pollex abductus | Absent | Absent |
| Ligaments | Normal | MP UCL lax | MP UCL and possibly RCL lax | MP UCL and possibly RCL lax | Absent | Absent |
| Bones and joints | All bones present, may be hypoplastic | All bones present, may be hypoplastic | All bones present, may be hypoplastic | Proximal metacarpal absent | Metacarpal, trapezium, and scaphoid absent | Phalanges, metacarpal, trapezium, and scaphoid absent |
Preoperative Evaluation and Treatment
A thorough history and complete physical examination of the patient is imperative. In addition to the upper extremities, the initial evaluation should include an assessment of the lower extremities, hips, back, head, and neck area. Although most cases of RLD are the result of sporadic mutations, some are related to underlying inherited conditions including Holt–Oram syndrome, thrombocytopenia absent radius, Fanconi’s anemia, and Blackfan–Diamond anemia ( Table 9.3 ). The frequency of association with a syndrome has been reported to range from 33% to 44% and nearly three quarters of patients have an accompanying medical or musculoskeletal anomaly. Therefore, it is imperative that the surgeon be aware of associated conditions and make certain that appropriate tests are completed at presentation, as often he or she is the first provider to accurately make the diagnosis ( Table 9.4 ).
| Associated Syndrome | Presentation | Inheritance Pattern |
|---|---|---|
| Holt–Oram | Radial longitudinal deficiency and a cardiac anomaly, most commonly a ventricular septal defect. | Autosomal dominant |
| TAR | Thrombocytopenia that manifests during infancy and can be fatal. Will resolve spontaneously with age. | Autosomal recessive |
| Fanconi anemia | Presents after age 3, commonly around 8–9 years old, with aplastic anemia. Historically, this condition was fatal; however, bone marrow transplants have been performed successfully to treat the anemia and prolong the life expectancy | Autosomal recessive |
| VACTERL association | A sporadic collection of anomalies consisting of vertebral deformity, anal atresia, cardiac anomalies, tracheoesophageal fistula, renal agenesis, and limb deformities | Sporadic |
|
|
|
|
Evaluation of the upper limb typically reveals some degree of radial deviation at the wrist and varying degrees of thumb hypoplasia. Importantly, there is little or no correlation between the severity of the thumb hypoplasia and radius involvement. Active and passive range of motion of the shoulder, elbow, wrist, and fingers should be recorded as well as the resting position of the radius and degree of obtainable passive correction. In the initial evaluation of a newborn with radial longitudinal deficiency, radiographs may not provide much additional information and are usually deferred until 6–12 months old.
Therapeutic intervention for these children begins within the first few months of life with passive stretching. As soon as these children are medically stable, a referral for occupational therapy should be made. Therapists lay early groundwork to promote best outcomes of complex surgeries and overall future functional independence. Potential functioning is optimized through interventions such as Active/Passive Range of Motion (A/PROM), developmentally appropriate activities of daily living (ADLs), engaging children in age appropriate play, and instructing parents how to safely stretch each joint of their child’s upper extremity. Parents, often, are hesitant and timid to stretch their child without a good understanding of their child’s anatomy, joint location, and attainable goals for increased range of motion (ROM). Each child is unique in their presentation, and thus a standardized approach is insufficient. It is important to understand the extent of each child’s individual abilities and functions, as many will need assistive devices or alternative techniques to become independent with ADLs early on.
During the initial therapy evaluation, as well as subsequent visits, it is important that the following items be noted:
- 1.
Is there a shoulder joint? How much ROM is available?
- 2.
Is there an elbow joint? How much ROM is available?
- 3.
What is the ROM of the wrist at rest? (How radially deviated is the wrist?)
- 4.
What is the available passive ulnar deviation of the wrist (typically a negative number)?
- 5.
Does the patient have a thumb?
- 6.
Is the thumb helpful in functional tasks?
- 7.
What position is the index finger in (Has it started to pronate)?
- 8.
How does the child hold objects (rattle, bottle, toys, etc.) … is it between the thumb and fingers, index and long, or ring and small?
- 9.
Look at Function—depending on the age of the child … is the child developmentally on target or are they having difficulty with certain tasks?
- 10.
Is there a need for an orthosis? (The need for orthotic fabrication depends on anatomy and presentation of the upper extremity. Orthoses will be discussed further in regards to specific joints throughout this chapter.)
All of these questions help the therapist plan therapeutic interventions to increase ROM, improve function, and help the surgeon plan for future surgery as the child grows.
It is important to assess all of these data points on a regular basis and communicate such with the treating surgeon so that changes in ROM and function are observed throughout development and patterns of decline or concern can be appropriately addressed.
As children grow, orthotic fabrication may become an important component of treatment. However, parent readiness, understanding of the purpose of the orthosis, and follow through is paramount before initiating an orthosis. Activities of daily living are also addressed at each of these stages, and children are instructed on the use of adaptive equipment or educated on an alternate method if completion is unobtainable.
Newborns less than 6 months old are typically easy to fabricate orthoses on; however, these orthoses are exceptionally small and require patience and precision to fabricate correctly. Encouraging caregivers to hold their baby during the fabrication process while maintaining a quiet and dimly lit atmosphere helps to soothe the child. It is important to remember that crying is a normal form of communication at this age. The typical orthoses for radial dysplasia may be something soft, such as cylindrical foam strapped onto the wrist radially, to act as a block for prevention of radial deviation ( Picture 9.1A and B ), or a custom-molded orthosis to hold the wrist into an ulnar-deviated stretch ( Picture 9.2A and B ). The primary activity of daily living at this age is feeding and parents rarely need assistance, as it is still age appropriate for children to breast or bottle feed. Grasping and reaching for toys is observed during this time, and alterations in the size of the toy or distance from reach can be easily adjusted ( Picture 9.3 ).
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
