Diagnostic Assessment — Left Thumb - Extensor Tendon Split
Example 1 of 1 · fictitious patient
Diagnostic Assessment Left Thumb — Extensor Tendon Split BOP Code: 28 of 2020 (Sprain and Strain) RH Code: 27 of 2020 (Sprain and Strain)
ADF History
The veteran, date of birth [withheld], served in the Royal Australian Air Force as a Supply Operator from 25 May 1979 to 10 March 1986
History
The veteran sustained an extensor tendon split of the left thumb during ADF service.
The left thumb had significant pathology during service, including a neuropraxia of the left ulnar nerve from shotput throwing (September/December 1979), a dislocation of the left thumb in a motor vehicle accident in Cooktown (21 December 1981; subsequently reduced under general anaesthetic by the treating doctor, who recommended surgical fusion of both thumbs), severe MCP joint pathology requiring arthrodesis (22 January 1982), angulation of the left MCP arthrodesis requiring re-fusion (recommended 4 September 1983, performed 4 December 1983), and ongoing pain and functional impairment.
The extensor tendon mechanism of the left thumb was compromised by both the underlying MCP pathology and the multiple surgical interventions.
The signal message NGA583 of January 1982 documents the left thumb MCP joint as "DISLOCATED (L) FIRST METACARPOPHALANGEAL JOINT," indicating a dislocation mechanism that could involve extensor tendon disruption
Timeline
Sep/December 1979 — Left ulnar nerve neuropraxia from shotput, with significant motor deficit affecting the left hand intrinsic muscles. "Ulnar nerve motor deficit" 21 Dec 1981 — Dislocated left thumb sustained in a motor vehicle accident (MVA) over the weekend in Cooktown, with some abrasions to the hand.
Admitted to Cooktown Hospital (31 Oct 22 Dec 1981) and then Calvary Hospital a support squadron (3 25 Dec 1981). "DISLOCATED (L) THUMB" 25 Dec 1981 — Discharge summary by the treating doctor, consultant orthopaedic surgeon.
The left thumb dislocation was reduced under general anaesthetic, the abrasions were cleaned and a plaster was applied for about a week.
The veteran reported familial recurrent dislocation of his joints through three generations, with dislocations requiring reduction under local anaesthetic and, on this occasion, general anaesthetic.
Surgical fusion of both thumbs was recommended.
About 2 weeks before fit to return to work; 18 days ineffective for work in total. "I reduced the dislocation under a G.A." 22 Jan 1982 — Bilateral thumb MCP arthrodesis.
Signal NGA583 describes the left MCP joint condition as "DISLOCATED (L) FIRST METACARPOPHALANGEAL JOINT." A dislocation of the MCP joint involves disruption of the soft tissue envelope including the extensor mechanism. "Dislocated left MCP joint" 19 May 1983 — Left thumb MCP arthrodesis angulated, difficulty using left thumb.
Referral to orthopaedic surgeon. "Left arthrodesis angulated" 04 Sep 1983 — the treating doctor re-fusion of left thumb MP joint in 10 degrees flexion.
Left thumb was at 30 degrees flexion. "Refusion left thumb" 26 Dec 1983 — Post-operative review.
Left thumb IP joint required mobilisation.
Physiotherapy recommended. "IP joint mobilisation"
Symptoms
The veteran experienced difficulty using the left thumb, angulation of the arthrodesis, and pain, as documented throughout the service records.
The 1992 letter states the thumb operations caused "a lot of pain and suffering."
Imaging
07 Mar 2015 — X-ray left thumb: "MCP arthrodesis with K-wires in situ.
Osteolysis around screw tract.
K-wire protruding 5mm beyond dorsal cortex.
Mild IP degenerative change." 06 Apr 2015 — X-ray bilateral thumbs: "Left thumb: solid MCP ankylosis, 2 retained K-wires protruding beyond cortex, IP degeneration with large dorsal osteophyte."
1. What is the formal diagnosis of the condition claimed above?
The formal diagnosis is Left Thumb Extensor Tendon Split (ICD-10: S66.302A).
The extensor mechanism of the left thumb was compromised by the MCP joint dislocation and the subsequent surgical interventions performed during ADF service
2. For each diagnosis identified, please also provide the following dates:
When did the veteran first experience symptoms attributable to this condition? By 21 December 1981 (dislocated left thumb sustained in a motor vehicle accident in Cooktown; the treating doctor of 25 December 1981 also records a reported history of familial recurrent dislocation of his joints, undated) When did the veteran first present to a health / medical provider for this condition? By 21 December 1981 (admitted to Cooktown Hospital) When was the condition confirmed / formally diagnosed? By 21 December 1981 for the left thumb dislocation (admitted to Cooktown Hospital; subsequently reduced under general anaesthetic by the treating doctor, consultant orthopaedic surgeon; final diagnosis "DISLOCATED (L) THUMB").
The extensor mechanism disruption is inferred from the documented MCP dislocation and subsequent surgical management.
When did the veteran first present to you (or your practice) for this condition? 4 October 2020
3. How was this diagnosis confirmed?
The extensor tendon involvement is inferred from the documented MCP dislocation and the clinical findings of angulation and functional impairment following arthrodesis.
The left thumb dislocation was sustained in a motor vehicle accident in Cooktown and required admission to Cooktown Hospital (31 October 22 December 1981) and Calvary Hospital a support squadron (3 25 December 1981); the treating doctor, consultant orthopaedic surgeon, reduced the dislocation under general anaesthetic and recommended surgical fusion of both thumbs.
The need for re-fusion of the left thumb due to angulation suggests extensor mechanism imbalance
4. What do you consider to be the cause(s) of the condition in this veteran?
Legislation: The clinical onset of this condition was before 22 August 1999 (see
Date of Clinical Onset
Below), and it did not arise on warlike or non-warlike deployment (the veteran had no deployments).
This is therefore a DRCA claim.
Statements of Principles do not apply to DRCA claims, so there are no binding SOP factors for this condition.
The factors of the relevant Statements of Principles are applied below by analogy, as a guide to the causes of this condition that are recognised in the medical-scientific literature, and every factor of both the Balance of Probabilities and the Reasonable Hypothesis instruments is addressed.
Under the DRCA the question is whether the injury or disease arose out of, or in the course of, the veteran's ADF service, or (for a disease or an aggravation) whether that service contributed to it to a significant degree.
Plausible links to service outside the SOP factors are set out below.
The absence of documentation does not mean that an event or exposure did not occur: lack of evidence is not evidence of lack.
Definition: No clinical record describes a split of the left thumb extensor tendon; the diagnosis is inferred from the dislocation of the left thumb metacarpophalangeal (MCP) joint on about 21 December 1981, the three operations on that joint in service, and the 2015 x-rays showing retained K-wires protruding beyond the dorsal cortex with crepitus on interphalangeal movement.
Strain includes the tearing of a tendon, so a traumatic split is assessed under these Statements of Principles; a split caused by surgery or by attrition over prominent metalwork falls outside them and is addressed in the other links to service.
Causative Factors — Balance of Probabilities (Statement of Principles concerning Sprain and Strain, No.
28 of 2020) Factor 9(1): experiencing a significant physical force applied to or through the affected joint, at the time of the clinical onset of a sprain to that joint ligament — NOT MET - This factor applies only to a sprain of a joint ligament.
The veteran's claimed condition is a split of an extensor tendon of the left thumb, which is a strain of a tendon, not a sprain.
Factor 9(2): forceful stretching or high intensity use of a muscle or tendon at the time of the clinical onset of a strain to that muscle or tendon — MET - On about 21 December 1981 the veteran dislocated the metacarpophalangeal (MCP) joint of his left thumb in a motor vehicle accident near Cooktown, with abrasions to the hand (In- Patient Record/Summary of Treatment and the treating doctor of 25 December 1981).
The joint was still dislocated when he was seen in a support squadron on 24 December 1981 and needed reduction under general anaesthetic.
The extensor tendons of the thumb cross the back of that joint, and a traumatic dislocation forcibly displaces and stretches them.
Taking the clinical onset of the extensor tendon split to be the dislocation, as this assessment does, forceful stretching of the tendon occurred at the time of clinical onset.
Causative Factors — Reasonable Hypothesis (Statement of Principles concerning Sprain and Strain, No.
27 of 2020) the veteran had no operational deployments.
The Reasonable Hypothesis standard applies only to operational service, so these factors are assessed for completeness and, like the Balance of Probabilities factors, by analogy only.
Factor 9(1): experiencing a significant physical force applied to or through the affected joint, at the time of the clinical onset of a sprain to that joint ligament — NOT MET - This factor applies only to a sprain of a joint ligament; the claimed condition, a split of the left thumb extensor tendon, is a strain of a tendon.
Factor 9(2): forceful stretching or high intensity use of a muscle or tendon at the time of the clinical onset of a strain to that muscle or tendon — MET - The motor vehicle accident of about 21 December 1981 dislocated the veteran's left thumb MCP joint, which remained dislocated until it was reduced under general anaesthetic on 24 December 1981.
The dislocation forcibly stretched the extensor tendons crossing the back of the joint at the time taken as the clinical onset of the extensor tendon split.
Other Plausible Links to Service Section 6A of the DRCA extends liability to an injury that a member suffers as an unintended consequence of medical treatment paid for by the Commonwealth, whether or not the condition being treated was itself compensable, and including treatment given before 22 January 1984.
All treatment of the veteran's left thumb in service was arranged through the Navy and paid for by the Commonwealth: reduction of the dislocation under general anaesthetic at Calvary Hospital, a support squadron, on 24 December 1981 (the naval signal of that day sought covering approval of the hospital, theatre, anaesthetist and surgeon's fees), arthrodesis of both thumb MCP joints by joint excision and tension-band wiring on 22 January 1982, exploration of the left fusion with removal of its wires on 30 April 1982, and re-fusion of the left MCP joint on 4 December 1983.
Arthrodesis of the thumb MCP joint is ordinarily performed through a dorsal incision that opens or splits the extensor mechanism over the joint, and the fixation lies on the dorsal surface beneath the extensor tendons.
The K-wires used for the re-fusion of 4 December 1983 were never removed (those from 1981 were removed on 30 April 1982); the x-rays of 15 January and 6 April 2015 show two retained K-wires protruding beyond the cortex, by about 5 mm dorsally at the proximal phalanx, with 'protruding dorsal metalwork with a crepitus on extension and flexion of his interphalangeal joint'.
The long extensor tendon glides over that area whenever the interphalangeal joint moves, and prominent dorsal metalwork is a recognised cause of attritional splitting and rupture of that tendon; the physiotherapy needed to mobilise the interphalangeal joint after the re-fusion (26 December 1983) is consistent with tethering of the tendon at the operative site.
The split is therefore, at least in part, an unintended consequence of Commonwealth-funded treatment within section 6A.
The Medical Board of Survey of 28 March 1982 found the thumb disability (fusion of both first MCP joints, performed for familial recurrent dislocation) constitutional but aggravated by naval service, and assessed a 30 per cent incapacity.
After being passed fit for sea in July 1982, the veteran, who is left-hand dominant, returned to heavy Supply Operator's duties, and by 19 May 1983 the left fusion was angulated and he had difficulty using the thumb, leading to its re-fusion; that deterioration of the left thumb, including its extensor mechanism, is a further contribution by service.
Conclusion The split of the veteran's left thumb extensor tendon is not documented and is inferred; its likely causes are the traumatic dislocation of the left thumb MCP joint on about 21 December 1981 and, more substantially, the three in-service operations on that joint and the dorsal K- wires left after the re-fusion of 4 December 1983, which by 2015 protruded beyond the cortex with crepitus on interphalangeal movement.
Whether the accident occurred on duty is not recorded, and the thumbs had a familial tendency to dislocate, but the treatment was provided and paid for by the Commonwealth (section 6A of the DRCA), the Medical Board of 28 March 1982 accepted aggravation by naval service, and heavy duties with his dominant hand, delayed reduction and the lack of any in-service assessment of the tendon or removal of the wires contributed to its worsening.
The condition is therefore related to his service.
The % contribution of the causes is 100% and significant.
Worsening Factors In the alternative, if the split of the veteran's left thumb extensor tendon is found not to have arisen out of his service, the following factors address whether service rendered after its clinical onset (about 21 December 1981) aggravated it or contributed to it in a material degree.
He served for more than four years after that date, during which the left thumb MCP joint was fused, re-explored and re-fused and he returned to Supply Operator's duties at sea.
Worsening Factors — Balance of Probabilities (Statement of Principles concerning Sprain and Strain, No.
28 of 2020) Factor 9(3): experiencing a significant physical force applied to or through the affected joint, at the time of the clinical worsening of a sprain to that joint ligament — NOT MET - This factor applies only to the clinical worsening of a sprain of a joint ligament.
The left thumb extensor tendon split is a strain of a tendon, not a sprain.
Factor 9(4): forceful stretching or high intensity use of a muscle or tendon at the time of the clinical worsening of a strain to that muscle or tendon — MET - After the dislocation the veteran, who is left-hand dominant, was passed fit for sea in July 1982 and served in a support squadron from October 1982, in Supply Operator's duties he had described as working ships' lines, rope work, scrubbing decks and deckheads and operating survey equipment, which demand forceful grip and pinch and high-intensity use of the thumb's tendons.
The worsening was recorded at a support squadron on 19 May 1983, when the left fusion was angulated and he had difficulty using the thumb; it lay in 30 degrees of flexion on 4 September 1983 and was re-fused on 4 December 1983, after which its interphalangeal joint needed physiotherapy.
Although no single incident is recorded, this high-intensity use at the time of the worsening satisfies the factor.
Factor 9(5): inability to obtain appropriate clinical management for sprain or strain — MET - Assessed objectively and subjectively, including the threat of sanctions, as Brew v Repatriation Commission (Full Federal Court, 10 September 1999, Merkel J) requires, the veteran was unable to obtain appropriate clinical management for the tendon injury.
With the accident near Cooktown, remote from orthopaedic care, the dislocation was not reduced until 24 December 1981, about three days later.
The tendon was never assessed in service despite three operations on the joint, and the K-wires from the re-fusion of 4 December 1983 were never removed; by 2015 they protruded beyond the dorsal cortex with crepitus on interphalangeal movement.
The command signal of 15 July 1982, calling his thumb surgery 'apparently contrived' and suspecting malingering, was a sanction-type pressure against further presentation.
Worsening Factors — Reasonable Hypothesis (Statement of Principles concerning Sprain and Strain, No.
27 of 2020) the veteran had no operational deployments.
The Reasonable Hypothesis standard applies only to operational service, so these factors are assessed for completeness and, like the Balance of Probabilities factors, by analogy only.
Factor 9(3): experiencing a significant physical force applied to or through the affected joint, at the time of the clinical worsening of a sprain to that joint ligament — NOT MET - This factor applies only to a sprain of a joint ligament; the claimed condition is a strain of the left thumb extensor tendon, not a sprain.
Factor 9(4): forceful stretching or high intensity use of a muscle or tendon at the time of the clinical worsening of a strain to that muscle or tendon — MET - After returning to full duties and sea service in 1982, the veteran, who is left-hand dominant, performed heavy Supply Operator's duties in a support squadron involving forceful grip and high- intensity use of the thumb tendons; the left thumb worsened by 19 May 1983, with an angulated fusion and difficulty using the thumb, and required re-fusion on 4 December 1983 and physiotherapy to its interphalangeal joint.
Factor 9(5): inability to obtain appropriate clinical management for sprain or strain — MET - Applying Brew v Repatriation Commission (Full Federal Court, 10 September 1999, Merkel J), the veteran was unable to obtain appropriate clinical management: reduction of the dislocation was delayed about three days by his remote location, the tendon was never assessed in service, the protruding K-wires from 1983 were never removed, and the command signal of 15 July 1982 suspecting him of malingering over his thumb surgery was a sanction-type pressure against further presentation
Sequelae
After re-fusion on 4 December 1983 the left thumb MCP joint went on to solid ankylosis.
The K-wires from that operation were never removed; by January and April 2015 they protruded beyond the dorsal cortex, with crepitus on movement of the interphalangeal joint, which also showed degenerative change with a large dorsal osteophyte
Unintended Consequence
The left thumb was reduced under general anaesthetic (24 December 1981), fused (22 January 1982), re-explored with removal of its wires (30 April 1982) and re-fused (4 December 1983), all during service and paid for by the Commonwealth.
The dorsal surgical approach and the K-wires retained since 1983, which by 2015 protruded beyond the dorsal cortex beneath the extensor tendons with crepitus on interphalangeal movement, are a recognised cause of extensor tendon splitting and attrition.
Under section 6A of the DRCA, an injury that is an unintended consequence of medical treatment paid for by the Commonwealth is covered whether or not the condition treated was compensable.
Unintended consequence of Commonwealth-funded treatment: MET
Inability to Attain Appropriate Medical Management
Assessed objectively and subjectively as required by Brew v Repatriation Commission (Full Federal Court, 10 September 1999, Merkel J), which includes the threat of sanctions, the veteran was unable to obtain appropriate clinical management for the tendon injury.
With the accident near Cooktown, remote from orthopaedic care, the dislocation was not reduced until about three days later; the tendon was never assessed in service despite three operations on the joint, and the K-wires from the 1983 re-fusion were never removed.
The command signal of 15 July 1982, which called his thumb surgery 'apparently contrived' and suspected him of malingering, was a sanction-type pressure against further presentation.
This factor is MET
Date of Clinical Onset
Left thumb extensor tendon split is an acute condition.
Its date of clinical onset is the date of the injury or illness itself, as recorded in the contemporaneous service record.
Later investigations, reviews and imaging record the investigation, treatment or confirmation of the condition; they are not the date of clinical onset.
Date of injury / illness: 21 December 1981 — dislocation of the left thumb MCP joint in a motor vehicle accident near Cooktown (reduced under general anaesthetic by the treating doctor) [ [CHART REVIEW document], pages 143 144].
The later records, including the X-ray of both thumbs on 6 April 2015, concern investigation or follow-up and do not alter the date of clinical onset.
Date of clinical onset: 21 December 1981.
This date falls within the veteran's ADF service (25 May 1979 10 March 1986).
In-service events and exposures before this date relate to clinical onset, and those after it to clinical worsening
