Hallermann–Streiff syndrome (HSS) is an extremely rare condition, with approximately 200 cases reported globaly ^[1]. First described by Aubry in 1893, and later characterized by Hallermann and Streiff, it is primarily recognized for its craniofacial dysmorphisms, ocular anomalies, and dermatologic features ^[2,3] a recent estimates a prevalence of 1 in 10 million in Japan ^[4]. The syndrome includes features such as bird-like facies, mandibular hypoplasia, microphthalmia, congenital cataracts, blue sclerae, hypotrichosis, cutaneous atrophy, and dental anomalies ^[5,6]. Although the exact etiology remains unknown, some cases have been associated with mutations in the GJA1 gene, suggesting a possible dominant inheritance pattern, though this remains unconfirmed ^[7]. Skeletal abnormalities, including cortical thinning of long bones, poor ossification, and disproportionate stature, are reported. However, no prior documentation exists of traumatic or periprosthetic fractures in patients with HSS. This case highlights such an occurrence, emphasizing the need for awareness of underlying bone fragility and anatomical considerations in surgical planning.

A 12-year-old male with confirmed HSS presented to the emergency department following a fall from standing height during transfer to his wheelchair. He reported immediate right thigh pain, functional limitation, and localized edema without skin lesions. The patient had a prior history of right femoral shaft fracture treated with ORIF using a dynamic compression plate (DCP) in 2020. On physical examination, he exhibited multiple classical features of HSS, including craniofacial dysmorphia, hypotrichosis, nystagmus, strabismus, blue sclerae, mandibular hypoplasia, and syndactyly. Skeletal findings included scoliosis and previous fracture history.

Diagnostic assessment

Plain radiographs of the right femur were obtained (Fig. 1), revealing a diaphyseal mid-third fracture with a simple fracture line located immediately distal to the previous osteosynthesis material, cortical thinning was noted without pathological lesions.

Figure 1: Anteroposterior (AP) X-ray of the right femur, February 26, 2025. AP radiograph of the right femur showing a displaced periprosthetic femoral fracture with varus angulation, displacement, and shortening (red arrows). Previous osteosynthesis material is visible without signs of fatigue or loosening (star). Adequate corticomedullary differentiation is observed in the diaphyseal region, along with cortical thinning (green arrows).

Therapeutic intervention

Surgical intervention involved the removal of the prior DCP and ORIF using a new 10-hole, 4.5 mm narrow DCP. Intraoperative findings included femoral shaft thinning and elongation with adequate cortical consistency and no gross pathological changes. Alignment was restored in axial and sagittal planes, verified by intraoperative imaging. Postoperatively, the patient was managed with restricted weight-bearing and allowed passive and active mobilization.

He was discharged on postoperative day 2 with close follow-up scheduled. At 3 weeks, the patient was asymptomatic, with proper wound healing and functional mobility. Radiographs confirmed maintained reduction and early consolidation (Fig. 2). At 6 months, he remained pain-free with good hip mobility and radiological evidence of Grade IV callus formation (Fig. 3).

Figure 2: X-ray follow-up. Immediate post-operative anteroposterior (AP) (A) and lateral (B) radiographs showing fracture line reduction (green arrow) and placement of osteosynthesis material (red arrow); (C) AP; and (D) lateral radiographs at 3 weeks postoperatively showing maintained reduction and Grade II consolidation (green arrow).

Figure 3: X-ray 6 months follow-up. Anteroposterior (A) and lateral (B) radiographs at 6-month follow-up showing Grade IV consolidation with prominent callus formation (green arrow), osteosynthesis material without signs of fatigue or loosening, and proper alignment without rotation or angular deformities.

The skeletal phenotype in HSS includes craniofacial and axial deformities, but literature on long bone fragility is sparse. Radiologically, features include poor ossification, thin diaphyseal cortices, and narrow medullary canals ^[8,9]. In our patient, cortical thinning was evident, though the corticomedullary differentiation appeared adequate. Existing literature reports congenital fractures in neonates with HSS, typically discovered during the perinatal period or at autopsy (Table 1). These cases often lack a traumatic trigger and are associated with impaired bone remodeling or abnormal ossification. However, no prior reports have documented traumatic or periprosthetic femoral fractures in HSS patients, making this case unique.

Table 1: Summary of reported cases of fracture in patient with HSS

This case suggests that, beyond craniofacial anomalies ^[10], patients with HSS may possess underlying long bone fragility predisposing them to fractures even under low-energy trauma. The presence of previous internal fixation may further increase the risk of peri-implant fractures due to stress shielding and local bone remodeling. From a surgical standpoint, challenges include anatomical abnormalities, altered biomechanics, and limited literature to guide implant selection or weight-bearing protocols. A low-profile DCP was selected to accommodate the narrow femoral diameter and avoid further periosteal damage. The favorable outcome observed supports the use of tailored internal fixation in such patients, along with close monitoring of healing progression. It underscores the importance of multidisciplinary management, involving orthopedic, genetic, and rehabilitation teams.

This is the first reported case of a traumatic periprosthetic femoral fracture in a patient with HSS. The case illustrates the need for heightened clinical awareness of possible bone fragility in these patients, especially in the context of previous fractures or implants. Multidisciplinary management, individualized surgical planning, and vigilant follow-up are essential in ensuring optimal outcomes. Documenting such cases contributes to the scarce literature and may guide future management strategies for similar rare presentations.

HSS, though extremely rare, can present with unanticipated long bone fragility, making patients vulnerable to fractures even after minor trauma. Awareness of these skeletal abnormalities, combined with multidisciplinary evaluation and individualized surgical planning, is critical to prevent complications, optimize recovery, and expand the scarce evidence base to guide management of future cases.