Left Ankle - Os Trigonum Syndrome — DVA claim example

Diagnostic Assessment — Left Ankle - Os Trigonum Syndrome

Example 1 of 1 · fictitious patient (Veteran BM)

Diagnostic Assessment

Left Ankle - Os Trigonum Syndrome

No Statement of Principles applies to this condition (non-SOP claim).

ADF History

Veteran BM, date of birth 19 August 1981, Australian Army, Infantry Soldier (Paratrooper, later Corporal), enlisted 08 May 2000, medically discharged 30 March 2014. Operational service: Solomon Islands, 24 July 2003 to 28 November 2003 (non-warlike); Afghanistan, 11 September 2006 to 26 April 2007 (warlike); Afghanistan, 03 May 2010 to 14 December 2010 (warlike).

Occupational History

As a paratrooper in a parachute-capable infantry battalion the veteran made static-line parachute descents, often at night and with equipment containers of 30 kilograms or more, and conducted long loaded marches, airfield seizure drills and helicopter and vehicle insertions. Parachute landings, jumping from vehicle tailgates and helicopter ramps, and patrolling over broken ground repeatedly force the ankle into end-range plantarflexion and inversion under load.

Infantry patrolling in Afghanistan involved carrying 40 to 55 kilograms over rocky, terraced and irrigated ground, climbing and dropping from compound walls, and running for cover under fire. Ankle sprains and fractures are among the most common injuries in this trade, and on operations they are usually managed by strapping and early return to duty, without imaging or specialist review.

History

Veteran BM, an Army paratrooper, developed posterior impingement from an os trigonum of the left ankle on 19 March 2007 during warlike service in Afghanistan, after a distal fibular fracture on a parachute landing in 2005, chronic lateral ankle instability and a forced plantarflexion sprain while dropping from a compound wall in February 2007. The condition worsened on his 2010 Afghanistan deployment after a further hyperplantarflexion injury and months of heavily loaded patrolling, and he required arthroscopic excision of the os trigonum in 2011.

Timeline

• 14 Aug 2005 — On a night training parachute descent in Australia the veteran landed heavily on uneven ground with his left foot plantarflexed and inverted, carrying a 32 kilogram equipment container. X-ray showed an undisplaced avulsion fracture of the tip of the left lateral malleolus (Weber A) and a moderate lateral ligament sprain. He was immobilised in a walking boot for six weeks. "Weber A fibular avulsion fracture"
• 20 Apr 2006 — Physiotherapy review recorded three further left ankle inversion sprains since the fracture, on runs and parachute landings, with a positive anterior drawer test, increased talar tilt and a sensation of the ankle giving way on uneven ground. The physiotherapist diagnosed chronic lateral ankle instability and he was fitted with a lace-up brace for parachuting and field work. "chronic lateral instability, giving way"
• 28 Aug 2006 — Pre-deployment health assessment for Afghanistan. The veteran reported intermittent lateral ankle giving way but no posterior ankle pain. Examination showed full painless plantarflexion, a negative posterior impingement test and lateral ligament laxity. "no posterior pain, impingement negative"
• 06 Feb 2007 — On warlike service in Afghanistan the veteran dropped about 2 metres from a compound wall carrying 48 kilograms and landed on the ball of his left foot, forcing the ankle into extreme plantarflexion and inversion. The medic recorded posterior and lateral ankle swelling, pain at the back of the ankle on pointing the foot and an inability to bear weight for a day. The ankle was strapped and he returned to patrolling after five days. "hyperplantarflexion injury, posterior swelling"
• 20 Mar 2007 — The veteran presented with deep posterolateral left ankle pain that had begun the previous day on a long loaded patrol, worse with downhill walking, pushing off and kneeling with the feet pointed, and pain on the big toe moving. Forced passive plantarflexion reproduced the pain and there was tenderness behind the peroneal tendons. The medical officer suspected posterior ankle impingement. Imaging was not available in theatre. "posterior pain on forced plantarflexion"
• 05 Jun 2007 — After return to Australia, X-ray and MRI of the left ankle showed a large os trigonum with bone marrow oedema on both sides of the synchondrosis, posterior synovitis and fluid around the flexor hallucis longus tendon. An orthopaedic foot and ankle surgeon diagnosed os trigonum syndrome triggered by the February 2007 injury. A diagnostic and therapeutic ultrasound-guided corticosteroid injection gave complete temporary relief. "os trigonum syndrome, injection relief"
• 17 Aug 2010 — On his second warlike deployment to Afghanistan the veteran jumped from a helicopter ramp at a landing zone carrying 52 kilograms and again forced his left ankle into hyperplantarflexion. Over the following four weeks of daily loaded patrols his posterior ankle pain became constant, with night pain, swelling and locking of the big toe. He could no longer run and was placed on base duties. "constant posterior pain, base duties"
• 26 Jan 2011 — Orthopaedic review after return recorded worsening since August 2010. Repeat MRI showed increased marrow oedema of the os trigonum and posterior talus, a fluid-filled, unstable synchondrosis, extensive posterior synovitis and flexor hallucis longus tenosynovitis. Repeat injection gave only two weeks of relief, and on 14 April 2011 the os trigonum was excised arthroscopically, with release of the flexor hallucis longus tendon. "unstable synchondrosis, excision planned"

Symptoms

At onset the veteran had deep pain at the back and outer side of the left ankle, brought on by pointing the foot, pushing off, walking downhill, descending stairs and ladders and kneeling, with pain at the back of the ankle when the big toe moved. The pain eased with rest but recurred with every loaded patrol.

From August 2010 the pain became constant, with night pain, posterior swelling and catching of the big toe, and he could not run. After the 2011 excision he improved but has persisting posterior and lateral ankle pain with prolonged walking, stiffness of plantarflexion and recurrent giving way on uneven ground. He cannot run, jump or carry loads.

Imaging

• 14 Aug 2005 — X-ray left ankle: "Undisplaced avulsion fracture of the tip of the lateral malleolus. Incidental large os trigonum posterior to the talus."
• 05 Jun 2007 — X-ray and MRI left ankle: "Os trigonum measuring 11 millimetres with bone marrow oedema of the ossicle and the adjacent posterior talus across the synchondrosis. Posterior capsular synovitis and fluid in the flexor hallucis longus tendon sheath. Healed lateral malleolar avulsion. Attenuated anterior talofibular ligament."
• 26 Jan 2011 — MRI left ankle: "Increased oedema of the os trigonum and posterior talus. Fluid signal across the synchondrosis indicating instability. Extensive posterior synovitis and flexor hallucis longus tenosynovitis. Chronic tear of the anterior talofibular ligament."

Onset Date

The most likely date of onset of this condition is 19 Mar 2007.

At that date the veteran was on warlike service in Afghanistan with an infantry task group, conducting daily patrols carrying 40 to 55 kilograms over rocky and terraced ground. He had injured his left ankle in a hyperplantarflexion fall from a compound wall on 06 February 2007, and on a long loaded patrol on 19 March 2007 he developed deep posterolateral ankle pain on pushing off and downhill walking that has persisted since.

This date is appropriate because his pre-deployment examination of 28 August 2006 recorded full painless plantarflexion and a negative posterior impingement test, and he presented the following day, 20 March 2007, with pain reproduced by forced plantarflexion. MRI on 05 June 2007 confirmed active os trigonum syndrome. The date falls within warlike service and within continuous full-time service.

For the injury causes, the 1 year before onset runs from 19 Mar 2006 to 19 Mar 2007 and contains the hyperplantarflexion sprain of 06 February 2007; the 2 years before onset run from 19 Mar 2005 to 19 Mar 2007 and contain the lateral malleolar fracture of 14 August 2005. Chronic lateral ankle instability was diagnosed on 20 April 2006 and present at onset. For the loading causes, the 3 months before onset run from 19 Dec 2006 to 19 Mar 2007, during which he patrolled with 40 to 55 kilograms for 25 to 35 hours a week and repeatedly dropped from walls, vehicle tailgates and helicopter ramps.

For the worsening, the documented clinical worsening began on 17 Aug 2010 during warlike service in Afghanistan, with constant pain, night pain, locking of the big toe and removal from patrol duties, confirmed by MRI on 26 January 2011 showing an unstable synchondrosis. The 1 year before the worsening runs from 17 Aug 2009 to 17 Aug 2010 and contains the helicopter ramp injury of that day, and the 3 months before the worsening run from 17 May 2010 to 17 Aug 2010, during which he patrolled with 45 to 55 kilograms for more than 30 hours a week.

1. What is the formal diagnosis of the condition claimed above?

The formal diagnosis is Os Trigonum Syndrome of the left ankle (ICD-10 M25.872), a form of posterior ankle impingement. No Statement of Principles has been determined for os trigonum syndrome.

The os trigonum is a small accessory bone behind the talus, present in about one in ten people, joined to the lateral tubercle of the posterior talar process by a fibrous or cartilaginous synchondrosis. It usually causes no symptoms. Os trigonum syndrome develops when the ossicle is compressed between the posterior tibia and the calcaneus in forced plantarflexion, or when the synchondrosis is disrupted by injury, producing posterior ankle pain, swelling, synovitis and often inflammation of the adjacent flexor hallucis longus tendon. It is typically triggered by an acute hyperplantarflexion or inversion injury, or by repetitive end-range plantarflexion under load, as in parachuting, jumping, ballet, kicking and running downhill, and is made more likely by lateral ankle instability. Treatment is activity modification and injection, and excision of the ossicle when these fail.

The condition began on 19 March 2007 during warlike service in Afghanistan, six weeks after a hyperplantarflexion injury on a background of a service-related fibular fracture and chronic lateral instability, was confirmed by MRI and a foot and ankle surgeon on 05 June 2007, and worsened during warlike service in Afghanistan from August 2010, leading to excision in April 2011.

2. For each diagnosis identified, please also provide the following dates:

When did the veteran first experience symptoms attributable to this condition?

19 March 2007.

When did the veteran first present to a health / medical provider for this condition?

20 March 2007.

When was the condition confirmed / formally diagnosed?

05 June 2007.

When did the veteran first present to you (or your practice) for this condition?

19 June 2025.

3. How was this diagnosis confirmed? i.e. what were the key symptoms and signs, investigation results, specialist opinions?

The diagnosis was made by an orthopaedic foot and ankle surgeon on 05 June 2007 on the basis of posterolateral ankle pain reproduced by forced passive plantarflexion, tenderness behind the peroneal tendons and pain with movement of the big toe, supported by MRI showing a large os trigonum with bone marrow oedema across the synchondrosis, posterior synovitis and flexor hallucis longus tenosynovitis. Complete temporary relief after an ultrasound-guided injection into the posterior recess confirmed the os trigonum as the source of pain.

The worsening was established clinically from 17 August 2010, with constant pain, night pain, posterior swelling, catching of the big toe and removal from patrolling, and by MRI on 26 January 2011 showing increased oedema, an unstable fluid-filled synchondrosis and extensive synovitis. The failure of a repeat injection and the need for arthroscopic excision of the os trigonum on 14 April 2011, where an unstable, inflamed ossicle was found, confirm the worsening.

4. What do you consider to be the cause(s) of the condition in this veteran? Give consideration to constitutional and common risk factors, pre-existing injuries or diseases, and occupational or lifestyle risks, as well as direct causative mechanisms.

No Statement of Principles has been determined for os trigonum syndrome, so the claim is decided on the sound medical-scientific evidence of what causes and worsens the condition, without the limits a Statement of Principles would impose. The recognised causes below are drawn from the medical literature on os trigonum syndrome and posterior ankle impingement, and each is set out in the form used by the Repatriation Medical Authority.

Legislation: the clinical onset of this condition was on 19 March 2007, after 1 July 2004, during continuous full-time service that included warlike service in Afghanistan. This is a Military Rehabilitation and Compensation Act 2004 (MRCA) claim. Operational service is relevant to the veteran's warlike service in Afghanistan in 2006 to 2007, where the condition began, and in 2010, where it worsened, and his peacetime service covers the 2005 parachute training fracture and the ankle instability that followed. Each cause must be related to service. Under the beneficial approach required by the legislation, the absence of documentation does not mean that an event or exposure did not occur: lack of evidence is not evidence of lack.

Recognised causes on the medical-scientific evidence (no Statement of Principles)

Causative factors

Cause 1: having an acute hyperplantarflexion injury of the affected ankle within the 1 year before the clinical onset of os trigonum syndrome; — MET

- On 06 February 2007, during warlike service in Afghanistan, the veteran dropped about 2 metres from a compound wall carrying 48 kilograms and landed on the ball of his left foot, forcing the ankle into extreme plantarflexion. The medic recorded posterior ankle swelling and pain on pointing the foot. This was six weeks before onset, within the 1 year from 19 March 2006 to 19 March 2007, and MRI in June 2007 showed oedema across the synchondrosis consistent with this injury.

Cause 2: having a sprain of the lateral or posterior ligaments of the affected ankle within the 1 year before the clinical onset of os trigonum syndrome; — MET

- The 06 February 2007 fall also inverted the left ankle, with lateral swelling and tenderness over the lateral ligaments and inability to bear weight for a day. In addition, two inversion sprains on loaded patrols in Afghanistan were recorded in November 2006 and January 2007. All three sprains fell within the 1 year before onset, during warlike service.

Cause 3: having a fracture of the distal tibia, distal fibula, talus or posterior talar process of the affected ankle within the 2 years before the clinical onset of os trigonum syndrome; — MET

- On 14 August 2005, on a night training parachute descent with a 32 kilogram equipment container, the veteran sustained an avulsion fracture of the left lateral malleolus, shown on X-ray that day. The fracture was 19 months before onset, within the 2 years from 19 March 2005 to 19 March 2007, and it occurred in the course of his parachute duties during peacetime service.

Cause 4: having chronic lateral instability of the affected ankle at the time of the clinical onset of os trigonum syndrome; — MET

- After the 2005 parachuting fracture and sprain the veteran had three further inversion sprains, and on 20 April 2006 a physiotherapist recorded a positive anterior drawer test, increased talar tilt and giving way, diagnosing chronic lateral ankle instability. The instability was confirmed at the pre-deployment examination of 28 August 2006 and by an attenuated anterior talofibular ligament on MRI in June 2007, so it was present at onset. Lateral instability allows abnormal posterior talar movement that loads the os trigonum.

Cause 5: undertaking repetitive activities involving forced or end-range plantarflexion of the affected ankle, including parachute landings, jumping from a height, kicking or running on steep or uneven ground, for at least 10 hours per week for at least the 3 months before the clinical onset of os trigonum syndrome; — MET

- Throughout the 3 months before onset, from 19 December 2006 to 19 March 2007, the veteran patrolled for 25 to 35 hours a week over terraced and rocky ground in Afghanistan, repeatedly climbing down terraces, dropping from compound walls and jumping from vehicle tailgates and helicopter ramps under load, recorded in patrol reports and the task group duty records. These activities repeatedly compress the os trigonum between the tibia and calcaneus.

Cause 6: carrying loads of at least 20 kilograms while marching or patrolling for a cumulative total of at least 200 hours within the 6 months before the clinical onset of os trigonum syndrome; — MET

- From 19 September 2006 to 19 March 2007 the veteran patrolled carrying 40 to 55 kilograms of body armour, weapon, ammunition, water and electronic countermeasures equipment for about 30 hours a week, a cumulative total of more than 600 hours, during warlike service in Afghanistan. Heavy loads increase the plantarflexion forces through the posterior ankle at push-off and on descent.

Cause 7: undertaking at least 20 parachute descents within the 5 years before the clinical onset of os trigonum syndrome; — MET

- The veteran's parachute log records 47 static-line descents between March 2002 and July 2006, many at night and with equipment containers, all within the 5 years before onset, from 19 March 2002 to 19 March 2007. Parachute landing falls repeatedly load the ankle in combined plantarflexion and inversion, and his 2005 fracture occurred on one of these descents.

Cause 8: having flexor hallucis longus tenosynovitis or posterior ankle synovitis of the affected ankle at the time of the clinical onset of os trigonum syndrome; — MET

- The veteran had pain behind the medial and lateral malleoli with movement of the big toe on 20 March 2007, and MRI on 05 June 2007 showed fluid in the flexor hallucis longus tendon sheath and posterior capsular synovitis. The tenosynovitis arose from the same repetitive loaded plantarflexion on warlike service and was present at onset, crowding the posterior recess around the os trigonum.

Worsening factors

Worsening 1: having an acute hyperplantarflexion injury of the affected ankle within the 1 year before the clinical worsening of os trigonum syndrome; — MET

- On 17 August 2010, during warlike service in Afghanistan, the veteran jumped from a helicopter ramp at a landing zone carrying 52 kilograms and forced his left ankle into hyperplantarflexion. His pain became constant over the following four weeks, and MRI on 26 January 2011 showed an unstable synchondrosis. The injury was at the start of the worsening, within the 1 year from 17 August 2009 to 17 August 2010.

Worsening 2: carrying loads of at least 20 kilograms while marching or patrolling for a cumulative total of at least 200 hours within the 6 months before the clinical worsening of os trigonum syndrome; — MET

- From 17 February 2010 to 17 August 2010, through his pre-deployment training and his warlike service in Afghanistan from 03 May 2010, the veteran marched and patrolled with 45 to 55 kilograms for a cumulative total of more than 450 hours, recorded in training and patrol records.

Worsening 3: undertaking repetitive activities involving forced or end-range plantarflexion of the affected ankle, including parachute landings, jumping from a height, kicking or running on steep or uneven ground, for at least 10 hours per week for at least the 3 months before the clinical worsening of os trigonum syndrome; — MET

- From 17 May 2010 to 17 August 2010, on warlike service in Afghanistan, the veteran patrolled for more than 30 hours a week over steep terraced ground and irrigation ditches, with repeated helicopter insertions and drops from compound walls, as recorded in patrol reports.

Worsening 4: inability to obtain appropriate clinical management for os trigonum syndrome. — MET

- On warlike service in Afghanistan in 2010 the veteran could not obtain imaging, a guided injection or orthopaedic review for his known os trigonum syndrome, and no non-patrolling role was available until his pain made patrolling impossible in September 2010. Excision was not possible until April 2011, eight months after the worsening began, by which time the synchondrosis was unstable and the flexor hallucis longus tendon required release. Under Brew v Repatriation Commission (1999) this is an inability to obtain appropriate clinical management.

The % contribution of the causes is 100% and significant.

Sequelae

The left os trigonum syndrome is a sequela of the veteran's accepted left ankle conditions: the lateral malleolar fracture sustained parachuting in 2005, the chronic lateral ankle instability that followed it, and the hyperplantarflexion sprain sustained on warlike service on 06 February 2007. The condition and its surgery have left persisting posterior ankle pain and stiffness, and the altered gait has contributed to left knee pain and lumbar pain recorded from 2012.

Unintended Consequence

Met. After the 06 February 2007 injury and again after the August 2010 injury, ADF health providers strapped the ankle and returned the veteran to loaded patrolling within days, without imaging, a treatment decision provided and paid for by the Commonwealth (section 6A of the DRCA and the equivalent provisions of the MRCA). Continued loaded plantarflexion on the injured synchondrosis contributed to the onset and to the instability found at surgery.

Inability to Attain Appropriate Medical Management

MET. On warlike service in Afghanistan in 2007 and 2010 there was no imaging, no guided injection and no orthopaedic review available, and the veteran was returned to loaded patrolling on an injured ankle until he could no longer walk on patrol. Definitive investigation was delayed eleven weeks after onset and excision eight months after the worsening, during which the synchondrosis became unstable and the flexor hallucis longus tendon became involved. Applying the objective and subjective tests in Brew v Repatriation Commission (Full Federal Court, 10 September 1999, Merkel J), the absence of investigation and specialist treatment in the operational area amounted to an inability to obtain appropriate clinical management.

5. Please provide a Health Summary and a medication / prescribing history.

See attached report.

References

1. 14 Aug 2005, Emergency treatment record and X-ray left ankle report, Medical Officer and Radiologist
2. 20 Apr 2006, Physiotherapy assessment, Physiotherapist, Garrison health centre
3. 28 Aug 2006, Pre-deployment health assessment, Medical Officer, Garrison health centre
4. 06 Feb 2007, Patrol medic casualty record, Afghanistan
5. 20 Mar 2007, Deployed health record, Medical Officer, Afghanistan
6. 05 Jun 2007, X-ray and MRI left ankle report and orthopaedic consultation, Radiologist and Orthopaedic foot and ankle surgeon
7. 17 Aug 2010, Deployed health record, Medical Officer, Afghanistan
8. 26 Jan 2011, MRI left ankle report and orthopaedic review, Radiologist and Orthopaedic foot and ankle surgeon
9. 14 Apr 2011, Operation report, Orthopaedic foot and ankle surgeon