Case report  ·  Open access  ·  Peer reviewed

Bilateral palmar degloving and anterior glenohumeral disruption in an adolescent male following attempted tethered pendular transit: a case report

Jonathan P Vane,¹ Aisha N Karim,² Robert Tilney,³ Eleanor Whittaker⁴

¹Trauma and Orthopaedics ²Emergency Medicine ³Plastic and Reconstructive Surgery (Hand Service) ⁴Radiology
Hull University Teaching Hospitals NHS Trust, Hull, UK

Correspondence to Mr Jonathan P Vane,  [email protected]

Abstract

Background

The figure of the “superhero” — a costumed individual who traverses cities by means of suspended filaments — is a fixture of popular entertainment. The biomechanics of this mode of transit have been examined in the educational literature, with force estimates in the order of 1.5–2 kN repeatedly derived for a pendular swing of ordinary urban scale. ¹ Despite the predictability of these estimates, the literature contains no detailed clinical description of the injuries they would produce in a human participant. We present such a case.

A separate question — whether the preceding arachnid envenomation, which appears to have conferred on this patient the genuine ability to produce a tensile biological filament, in any way mitigated the injury — is addressed under Discussion. It did not.

Case presentation

A 16-year-old male was brought by ambulance to the major trauma centre at Hull Royal Infirmary at approximately 21:40 on a Saturday in June 2026, having fallen from the roof of a disused commercial building. According to the pre-hospital record and the account of two witnesses, the patient — who in the six weeks since an arachnid bite had demonstrated the ability to produce and project a strong biological filament from glands at both wrists — secured a line of this filament to a stone parapet and stepped from the parapet intending to swing across a gap of roughly ten metres to the adjacent building.

The filament held. The patient did not.

Timeline (from pre-hospital and ward records)

Examination

On arrival the patient was alert, oriented (GCS 15), and in severe pain. Both hands were still partially wrapped in the filament he had produced, beneath which the palmar surfaces had undergone circumferential degloving: the skin and superficial fascia of both palms had been avulsed from the underlying flexor tendon sheaths, remaining attached only by a narrow proximal bridge at the wrist. The flexor tendons themselves were exposed but intact. The right shoulder sat in an obvious anterior dislocation. Both heels were tender and deformed, and the left knee was swollen and held in flexion.

A small, healing bite mark was noted on the patient’s right forearm, which he attributed to a spider some six weeks earlier. Both wrists bore the orifices of the filament-producing glands (approximately 2 mm, volar aspect), quiescent on arrival but patent. Samples of the filament were retrieved from the scene by police and from the patient’s hands, and submitted for analysis (see Investigations).

Investigations

CT of the hands confirmed bilateral full-thickness soft-tissue loss to the palmar surfaces with preserved metacarpal and phalangeal architecture. CT of the right shoulder confirmed an anterior glenohumeral dislocation with a bony Bankart lesion. CT of the lower limbs showed bilateral displaced intra-articular calcaneal fractures (Sanders type III) and a left tibial plateau fracture (Schatzker II). No spinal injury was identified. Tensile testing of the retrieved filament (materials science, University of Hull) returned a breaking load in excess of 2.4 kN — well above the estimated peak in-vivo load. The filament was not the structure that failed.

Biomechanical analysis

The mechanism is well approximated by a simple pendulum of length L carrying a mass m, released from rest at horizontal. Taking the patient’s mass at 63 kg and the effective length from parapet to hands at 8.0 m, the linear speed at the lowest point of the arc is:

v = √(2gL) = √(2 × 9.81 × 8.0) ≈ 12.5 m·s⁻¹  (≈ 28 mph)

The centripetal requirement at this point yields a tensile load in the filament — and through the patient’s hands — of three times body weight:

T = m·g + m·v²⁄L = m·g + 2m·g = 3m·g ≈ 1850 N ≈ 417 lbf

Distributed across the palmar contact area of the adhered filament (of the order of 15 cm²), this load corresponds to a shear stress on the dermofascial plane of roughly 1–1.5 MPa — comfortably in excess of its in-vivo tolerance, which is consistent with the observed pattern of failure (de-gloving rather than fracture of the metacarpals or rupture of the filament).

The same 1850 N load acts as a distractive force across the glenohumeral joint, which dislocates under a small fraction of this value; anterior dislocation of the weight-bearing shoulder was therefore expected, and occurred.

It is worth stating what did not fail. The filament did not fail (breaking load > 2.4 kN). The patient’s grip did not fail — his hands remained closed on the line until the skin they closed with was no longer attached to them. The metacarpals did not fail. Failure was confined to the dermofascial plane of the palm: the one structure in the chain the patient’s anomalous capability had done nothing to reinforce.

These figures agree closely with the educational estimate of Minetti and others for a swing of comparable scale.¹ The patient’s injuries are, in effect, the experimental confirmation of a calculation previously assumed to be self-evidently theoretical.

Management

The patient was resuscitated per ATLS protocol. He was taken to theatre on the night of admission for wound debridement and split-thickness skin grafting to both palms (Mr Tilney, Hand Service), and closed reduction and stabilisation of the right shoulder under general anaesthesia. Bilateral calcaneal fractures were managed by orthopaedics with delayed open reduction and internal fixation; the left tibial plateau fracture was treated operatively within the same admission. He received tetanus prophylaxis and broad-spectrum antibiotics given the contaminated mechanism.

Outcome and follow-up

At the time of writing the patient remained an inpatient undergoing rehabilitation. He has undergone two further debridements of the right palm. Prognosis for grip recovery is guarded; prognosis for independent mobility is good but protracted, with a minimum of six months’ non-weight-bearing on the lower limbs anticipated. A further report will follow his rehabilitation.

Discussion

The central observation of this case is a mundane one: a calculation is not rendered safer by being performed by the person it endangers. The patient had, by his own account, “worked it out” and was confident the filament would hold. The filament did hold. His confidence was, in this narrow and crucial sense, correct, and entirely beside the point.

The pattern of integumentary failure — skin before tendon, tendon before bone, bone before filament — is worth recording. Popular depictions of this activity imply that grip is the limiting factor. It is not. The palm gives way first, and does so at a load independent of the participant’s effort or conviction.

On the anomalous capability. The patient’s ability to produce a biological filament of extraordinary tensile strength from the wrists is, in the authors’ view, beyond the scope of a case report to explain. We note it only insofar as it bears on the injury.

It bears on the injury in the following way. A filament strong enough to suspend a human will, by that property, generate forces sufficient to destroy the human hand that grips it. The capability selected for exactly the failure mode it then produced. Whatever the source of the filament — and we record the patient’s history of a preceding Steatoda nobilis bite without venturing a mechanism — it provided the means of injury without providing any of the means to survive it. The Noble false widow is, in its own ecology, a web-builder of modest scale; the apparatus suited to suspending a nine-milligram arachnid is, it appears, transferred without modification to a sixty-three-kilogram adolescent, with the results described above.

The bite, in short, gave the patient the silk and nothing else. For the spider that is a complete solution. For the boy it was the single component most likely to harm him.

Learning points

• The limiting structure in tethered pendular suspension of a human body is the palm’s dermofascial plane, not grip, bone, or filament.
• Peak tensile load approaches three times body weight even for a modest swing.
• An anomalous ability to produce a strong filament offers no protection against the load it generates, and may guarantee injury by ensuring the filament does not fail first.
• Apparatus suited to a 9 mg arachnid does not scale to a 63 kg adolescent. The silk alone is the most dangerous single component to possess.

References

1. Minetti AE, Minetti C. The biomechanics of spider-man: a teaching estimate of the peak loading in tethered urban transit. Phys Educ (educational correspondence) and similar derivations variously reproduced in the lay physics literature. Figures cited herein re-derived independently by the authors. [↩ return to the news report]
2. Dugon MM, Dunbar JP, Afoufa M, et al. The Noble false widow (Steatoda nobilis): a public health risk in the built environment, with notes on its expanding range in north-western Europe. Clin Toxicol / urban ecology literature, various years.
3. Bayat A, McGrouther DA, Ferguson MWJ. Skin wound healing: the clinical and pathological spectrum of palmar soft-tissue loss and degloving injury management.
4. Sanders R. Operative treatment of displaced intraarticular calcaneal fractures. (Classification referenced for the lower-limb injuries.)
5. Williams RL, Doe J. “Superhero physiology” and the seasonal literature of improbable injury. A recognised, if lightly regarded, subgenre.

To cite: Vane JP, Karim AN, Tilney R, Whittaker E. Bilateral palmar degloving and anterior glenohumeral disruption in an adolescent male following attempted tethered pendular transit. BMJ Case Rep 2026;19:e123456.