Tibial hemimelia-polysyndactyly-triphalangeal thumb syndrome: Case report and review of literature

Adnan Anwer; Yasir Salam Siddiqui; Mazhar Abbas; Madhav Chowdhry

doi:10.4103/jbjd.jbjd_12_23

CASE REPORTS

Year : 2023 | Volume : 38 | Issue : 1 | Page : 120-124

Tibial hemimelia-polysyndactyly-triphalangeal thumb syndrome: Case report and review of literature

Adnan Anwer, Yasir Salam Siddiqui, Mazhar Abbas, Madhav Chowdhry
Department of Orthopaedic Surgery, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India

Date of Submission	04-Mar-2023
Date of Acceptance	15-Mar-2023
Date of Web Publication	20-Apr-2023

Correspondence Address:
Madhav Chowdhry
Department of Orthopaedic Surgery, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jbjd.jbjd_12_23

Abstract

Triphalangeal thumb (TPT) is a rare clinical entity, with majority of cases being hereditary in origin. Two syndromes associated with TPT are triphalangeal thumb-polysyndactyly syndrome (TPTPS) and tibial hemimelia-polysyndactyly-triphalangeal thumb syndrome (THPTTS). Hypoplasia or aplasia of tibia is the primary difference between them. Although having many common clinical features, TPTPS and THPTTS are considered two different entities. Here, we report a rare situation of these two conditions occurring in the same family: a mother with TPTPS and her son with THPTTS. A 4-month-old male child presented to outpatient clinic with complaints of 2.5 cm shortening and clubfoot present on the right side. The child had five-fingered hands without thumbs or thenar muscles along with preaxial polydactyly with seven toes in the left foot and six toes in the right foot. Radiographic examination revealed hypoplasia of the right tibia (tibial hemimelia) with thickened and superolaterally displaced fibula. While applying cast for club foot to the child, his mother’s hands came into notice. The lady was 26 years old, born to nonconsanguineous parents, with no similar history in parents or siblings. Clinical examination of hands revealed TPTs in both hands. She had no difficulty in her activities of daily living. Her legs appeared normal. Her feet were normal except for the duplicated right great toe with fused nails and duplicated left great toe floating separately. TPTs, polydactyly of hands, and feet along with syndactyly of digits are cardinal findings seen in both TPTPS and THPTTS. Both can also be traced to 7q36. The presence of a tibial defect seems to be the only difference between the two disorders. In this case report, we highlight the occurrence of two seemingly different clinical entities within the same family, suggesting the possibility of an overlying common entity with a wide spectrum of clinical presentations.

Keywords: Congenital, hereditary, polydactyly, syndactyly, tibial hemimelia, tibial hemimelia-polysyndactyly-triphalangeal thumbs syndrome (THPTTS), triphalangeal thumb polydactyly syndrome (TPTPS), triphalangeal thumb

How to cite this article:
Anwer A, Siddiqui YS, Abbas M, Chowdhry M. Tibial hemimelia-polysyndactyly-triphalangeal thumb syndrome: Case report and review of literature. J Bone Joint Dis 2023;38:120-4

How to cite this URL:
Anwer A, Siddiqui YS, Abbas M, Chowdhry M. Tibial hemimelia-polysyndactyly-triphalangeal thumb syndrome: Case report and review of literature. J Bone Joint Dis [serial online] 2023 [cited 2023 Jun 7];38:120-4. Available from: http://www.jbjd.in/text.asp?2023/38/1/120/374422

Introduction

The first case of triphalangeal thumb (TPT) was reported by Columbi in 1559.^[1] This is a rare anomaly whose true incidence, although unknown, is estimated to be 1:25,000 live births.^[2] Two-thirds of these patients have a hereditary component and are characterized by an autosomal dominant transmission (mutation on chromosome 7q36).^[3] Such TPTs are mostly nonopposable, bilateral, and generally occur with other malformations of the hand or foot.^[4] Nonhereditary cases have been found to be linked to thalidomide and are usually unilateral and opposable.^[5] For proper coordination and manipulation of small objects in hand, adequate opposition of thumb with the long fingers of hand is required. Thumb length is an important factor in determining this. If the thumb is long, fine motor skills could be impeded.

Triphalangeal thumb-polysyndactyly syndrome (TPTPS) is an autosomal dominant disorder comprising TPT, polydactyly, and syndactyly. The malformations are usually bilateral and asymmetric. Hands are more severely affected than feet. TPT is a consistent finding and the index finger is almost always normal. The gene responsible for TPTPS was assigned to chromosome band 7q36 by linkage analysis.^[6]

Tibial hemimelia-polysyndactyly-triphalangeal thumbs syndrome (THPTTS) is another autosomal dominant disorder characterized by tibial hemimelia, polysyndactyly, and TPTs. TPT and tibial hemimelia are consistent findings of this syndrome. Children are usually affected more than those in their affected parents, suggesting genetic anticipation. It has also been mapped to the gene locus 7q36.^[7]

Although having many common clinical features, TPTPS and THPTTS are considered two different entities. Hypoplasia or aplasia of tibia is the primary difference between them. Also, THPTTS has not been present in large pedigree families. Here, we report a rare situation of these two conditions occurring in the same family: a mother with TPTPS and her son with THPTTS.

Case Report

In February 2022, a young lady presented to pediatric orthopedics clinic with a complaint of shortening of the right lower limb and inward deviation of the right foot of her son. The baby was the firstborn child, full term, delivered per vaginum with no antepartum or postpartum complication. On clinical examination, there was a shortening of 2.5 cm present on the right side with polydactyly as well as syndactyly present.

Patient 1

At 4 months of age, a male child of length 63 cm (between median to -2 standard deviation) and weight, 7.4 kg (between median to -2 standard deviation) presented to outpatient department. The child had five-fingered hands without thumbs or thenar muscles [Figure 1]a. His right leg was 2.5 cm shorter compared with the opposite side. There was a club foot present on the right side with cavus, adductus, and varus deformity with no equinus. He had preaxial polydactyly (PPD) with seven toes in the left foot and six toes in the right foot. The great toes were movable and appeared small and shorter than the supernumerary and the second toes. The supernumerary toes were well-formed and movable. The left preaxial polydactylous toes were webbed with the great toe. The rest of the toes of the left foot were normal. The right polydactylous second toe was webbed with the great toe, whereas the rest of the toes were normal [Figure 1]b and c. To establish hereditary cause, karyotyping was indicated; however, it was not available at the institution.

Figure 1: Clinical photographs of a 4-month-old male child. (a) Clinical photograph of both hands showing five fingers without thumbs. (b and c) Clinical photographs of bilateral feet displaying preaxial polydactyly with seven toes in the left foot and six toes in the right foot

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Radiographically, the first digit of both the hands showed a normally shaped additional middle phalanx (Wood’s type 3) [[Figure 2]a]. Radiograph of right leg [Figure 2]b showed hypoplasia of right tibia (tibial hemimelia). Fibula was thick and superolaterally displaced. Its metaphysis appeared small on both ends. [Figure 2]c shows anteroposterior (AP) radiograph of bilateral feet with the right foot showing second polydactylous great toe. Left foot showed two supernumerary metatarsal bones preaxially and with fused second and third proximal phalanx. Both great toes were found to be smaller.

Figure 2: Radiographs of bilateral hands, legs, and feet of a 4-month-old male child. (a) anteroposterior-radiograph of bilateral hands showing normally shaped additional middle phalanx in the first digit of both hands. Anteroposterior radiographs of right leg show hypoplasia of the right tibia (tibial hemimelia), with thickening and superolateral displacement of fibula. (c) anteroposterior radiograph of bilateral feet with right foot showing second polydactylous great toe. Left foot showed two supernumerary metatarsal bones preaxially and with fused proximal phalanx of the great toe and first supernumerary toe. Both great toes were found to be smaller

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Patient 2

While applying cast for club foot, as the mother used to hold the baby in her lap, her hands came in to notice. The lady was 26 years old, born to nonconsanguineous parents, with no similar history in parents or siblings. She had one child. Her height was 143 cm and weight was 61 kg. Clinical examination of hands revealed TPTs in both hands [Figure 3]a and [Figure 3]b. Visually, they appeared as hands with no thumbs. The fifth finger was opposable, ulnar deviated, and possessed normal carpometacarpal joint motions. She had no difficulty in her activities of daily living (ADL). Her legs appeared normal. Her feet were normal except for the duplicated right great toe with fused nails and duplicated left great toe floating separately [Figure 3]c and [Figure 3]d. To rule out other genetic abnormalities, karyotyping was indicated; however, it was not available at the institution.

Figure 3: Clinical photographs of the 26-year-old mother of the patient. (a and b) Clinical photograph of both hands showing four fingers and bilateral triphalangeal thumbs. Clinically, they appeared as hands with no thumbs. (c and d) Clinical photographs of bilateral feet demonstrating duplicated right great toe with fused nails and duplicated left great toe floating separately

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AP radiograph of bilateral hands demonstrated TPT in the left hand with well-developed middle phalanx, whereas the right hand demonstrated TPT with trapezoid-shaped middle phalanx [Figure 4]a. AP radiograph of the right foot demonstrated fused proximal phalanx with two separate distal phalanx of the second toe, whereas the left foot demonstrated separate first and second toes with fused distal phalanx of the second toe [Figure 4]b.

Figure 4: Radiographs of bilateral hands and feet of the 26-year-old mother of the male child. (a) anteroposterior radiograph of bilateral hands showing triphalangeal thumb of the left hand with well-developed middle phalanx, whereas the right hand demonstrated triphalangeal thumb with a trapezoid-shaped middle phalanx. (b) anteroposterior radiograph of the right foot demonstrated fused proximal phalanx with two separate distal phalanx of the second toe, whereas the left foot demonstrated separate first and second toes with fused distal phalanx of the second toe

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Discussion

TPT is associated with a wide range of clinical presentations. The functional problem that arises in many patients with this malformation is deficient opposition resulting in difficulty with activities such as writing and picking up smaller objects. When radial polydactyly is present along with it, the function of the best thumb of the two or three is blocked by the presence of the other(s), especially if syndactyly is present between the thumbs.

There are many theories in the literature regarding the origin of TPT. Some authors believe that, in human hand, each finger (including thumb) normally holds three phalanges and the metacarpus of the first ray evolves into the modern trapezium. This could explain the curved shape of the first metacarpal bone, which resembles the shape of the phalanges. The nutrient foramen of the first metacarpus is also similar to the one seen in phalanges. Other school of thought is that fusion occurs between the first metacarpus and the proximal phalanx. Windle’s theory of a shortened first ray is based on the absence of the distal phalanx.^[8]

TPT is classified using Wood’s classification based on the shape of the extra phalanx. The three types are type 1 (delta type) is found with ulnar deviation at the interphalangeal joint (type 1), the trapezoid type (type 2), and a fully developed extra phalanx (type 3).^[9] De Mas and Mele classified TPT according to the amount of thumb opposition in relation to the long fingers. It ranged from complete opposition to lateral pinch, that is, adduction in the same plane of the fingers (nonfunctional opposition). Buck-Gramcko^[10] used additional parameters such as intrinsic musculature, web space, and length. International Federation for Societies for Surgery of the Hand simply suggests considering TPT as a group III of the congenital hand malformation classification, that is, polydactyly.^[11]

In this case report, we highlight the occurrence of two seemingly different clinical entities within the same family, suggesting the possibility of an overlying common entity with a wide spectrum of clinical presentations. This hypothesis is based on the following findings. First, TPTs, polydactyly of hands and feet along with syndactyly of digits are cardinal findings in TPTPS and THPTTS. The presence of a tibial defect seems to be the only difference between the two disorders. Furthermore, it is likely that TPTPS is also causally related to Haas-type syndactyly because both were found in the same pedigrees. TPTPS, THPTTS, and PPD are all assigned to chromosome band 7q36.^[12]

Most people with TPT as hereditary disease are present with bilateral malformations.^[13] They generally do not show limitations in range of motion, and only in a few cases, the metacarpophalangeal joint (MCPj) remains unstable. Intrinsic movements of the thumb (anteposition, opposition, and MCPj flexion) along with grip and pinch strength are affected negatively. Self-reported function is not impeded but the presence of uni- or bilateral TPT influences the social aspects of patients.^[14],[15]

Our TPT patient, as mentioned earlier, was brought to our attention for club foot secondary to tibial hemimelia and could not return for extensive assessment as she became unreachable for follow-up once club foot got corrected by casting. We, therefore, could not fully subjectively and objectively assess the patient with standardized tools. Similar to most patients with this malformation, our patient was male with a family history of TPT with bilateral deformities and reported full function. On examination of his mother, no abnormal movements or instability were noticeable. His mother never sought medical attention for her TPT as all her ADLs were within normal limit. Appearance also did not seem to be an issue in our patient, unlike most other cases found in the literature, but we could not truly investigate on, possibly the most important aspect of TPT. Karyotyping forms the essential tool to further evaluate the association of two syndromes on a genetic level. In conclusion, it is likely that TPTPS and THPTTS are the same disorder with a wide variability of clinical presentation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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