Diagnostic Assessment — Left Knee - Plica Syndrome
Example 1 of 1 · fictitious patient (Veteran Y)
Diagnostic Assessment
Left Knee - Plica Syndrome
BOP Code: 8 of 2019 (Internal Derangement of the Knee)
RH Code: 7 of 2019 (Internal Derangement of the Knee)
ADF History
Veteran Y, date of birth 27 October 1983, Royal Australian Air Force, Airfield Defence Guard, enlisted 15 April 2002, medically discharged 06 June 2017. Operational service: Afghanistan, 04 February 2008 to 29 September 2008 (warlike); Afghanistan, 12 March 2012 to 19 November 2012 (warlike).
Occupational History
Airfield defence guards are the Air Force's ground combat specialists. The veteran conducted foot and vehicle patrols around air bases and forward locations carrying 35 to 45 kilograms of body armour, weapon, ammunition and radio, dismounted repeatedly from protected mobility vehicles, and trained in close-quarters combat, obstacle courses and fast roping. These tasks load the knee in flexion under weight and expose it to twisting, landing and direct-impact injuries.
On operations the work was performed over broken, rocky ground, irrigation ditches and compound walls at night under night-vision equipment, with limited ability to stop for injuries. Deployed health support is usually confined to a medic or regimental aid post, with no MRI or orthopaedic surgery available in theatre.
History
Veteran Y, an RAAF airfield defence guard, sustained a medial collateral ligament sprain and an acute medial meniscal tear of the left knee when he fell into an irrigation ditch on a night patrol in Afghanistan on 16 March 2008, and developed a chronic left knee disorder with a symptomatic, fibrosed medial plica from 23 June 2008. The condition was confirmed at arthroscopy in 2009 and worsened in 2013 after a further ligament sprain and meniscal tear of the same knee on his second Afghanistan deployment.
Timeline
- 21 Nov 2007 — Pre-deployment health assessment for Afghanistan. The veteran reported no knee symptoms. Examination of both knees was normal, with full range of motion, no effusion, stable ligaments and negative meniscal tests. He completed his fitness assessment, including a loaded pack march, without difficulty. "knees normal, ligaments stable"
- 16 Mar 2008 — On a night foot patrol in Afghanistan, carrying about 40 kilograms, the veteran stepped into an unseen irrigation ditch and his left knee was forced into valgus and twisted as he fell. He felt a pop on the inside of the knee and could not continue without assistance. The medic recorded medial joint line tenderness, swelling within two hours, pain on valgus stress at 30 degrees with a soft end point, and a positive McMurray test. He was treated with ice, compression and a hinged brace and placed on base duties. "valgus twist, medial pop, swelling"
- 02 Apr 2008 — Review at the role 2 facility recorded a grade 2 medial collateral ligament sprain with 5 to 7 millimetres of medial opening and an acute medial meniscal tear with locking episodes. MRI was not available in theatre and he was returned to modified patrol duties in a brace after four weeks because of manning pressures. No orthopaedic review was possible until his return to Australia. "grade 2 MCL sprain, meniscal tear"
- 24 Jun 2008 — The veteran re-presented with a new pattern of symptoms that had begun the day before: anteromedial left knee pain on stairs and squatting, painful clicking and catching as the knee moved through 30 to 60 degrees of flexion, and pain after prolonged sitting in vehicles. A tender, mobile band was palpable over the medial femoral condyle and the medial plica test was positive. The medic noted that the symptoms differed from his acute injury. "painful click, palpable medial band"
- 12 Nov 2008 — After return to Australia, MRI of the left knee showed a thickened medial patellar plica with surrounding synovitis, a healing grade 2 medial collateral ligament injury and a horizontal-oblique tear of the posterior horn of the medial meniscus with bone bruising consistent with acute injury. An orthopaedic surgeon diagnosed symptomatic medial plica syndrome following the March 2008 injury, with an associated meniscal tear. "thickened medial plica, synovitis"
- 17 Mar 2009 — Left knee arthroscopy by an orthopaedic surgeon found a thickened, fibrosed and inflamed medial plica impinging on the medial femoral condyle, with a groove of chondral softening beneath it, and an unstable posterior horn medial meniscal tear. The plica was resected and a partial medial meniscectomy performed. Histology confirmed fibrotic synovium with chronic inflammation. Medial collateral ligament laxity of grade 1 was recorded under anaesthesia. "fibrosed plica resected, meniscectomy"
- 05 Jul 2012 — During his second warlike deployment to Afghanistan the veteran jumped down from a compound wall under fire while carrying 42 kilograms and landed with his left knee flexed and rotated. He had immediate pain and swelling, a positive Lachman test with a firm end point, valgus pain and a locked knee that was manipulated free by the medical officer. A partial anterior cruciate ligament sprain and a new acute meniscal tear were recorded. MRI and surgery were not available in theatre. "partial ACL sprain, locked knee"
- 14 Feb 2013 — Orthopaedic review in Australia recorded recurrent painful catching and snapping across the anteromedial knee, persistent effusion and giving way. Repeat MRI showed regrowth of thickened synovial plica tissue with synovitis, a partial thickness anterior cruciate ligament tear and a new radial tear of the body of the medial meniscus. His knee pain score had risen from 3 out of 10 after the 2009 surgery to 7 out of 10, and he had been unable to run since July 2012. "plica regrowth, new meniscal tear"
- 22 Apr 2013 — Repeat arthroscopy found recurrent fibrotic plica and synovitis with grade 3 chondral change of the medial femoral condyle, a partial anterior cruciate ligament tear and a displaced radial medial meniscal tear. The plica and synovium were debrided and a further partial meniscectomy performed. He remained on restricted duties and was later medically discharged with a permanent restriction against loaded marching and patrolling. "recurrent plica debrided, chondral change"
Symptoms
At onset the veteran had anteromedial left knee pain on stairs, squatting and kneeling, a painful click or catch as the knee bent through mid-range, pain and stiffness after sitting for long periods in vehicles, and intermittent swelling. These symptoms differed from the acute medial pain of his March 2008 injury and persisted after the ligament sprain had settled.
After the 2012 injury the catching became frequent, with recurrent effusions, giving way on uneven ground and inability to run. He now reports daily left knee pain, worse on stairs and after kneeling or sitting, intermittent catching and swelling, and he cannot run, carry loads or squat fully.
Imaging
- 12 Nov 2008 — MRI left knee: "Thickened medial patellar plica measuring 3 mm with adjacent synovitis. Healing grade 2 medial collateral ligament sprain. Horizontal-oblique tear of the posterior horn of the medial meniscus with medial femoral condyle bone bruising consistent with acute injury."
- 14 Feb 2013 — MRI left knee: "Recurrent thickened synovial plica tissue over the medial femoral condyle with synovitis and joint effusion. Partial thickness tear of the anterior cruciate ligament. New radial tear of the body of the medial meniscus. Focal chondral thinning of the medial femoral condyle."
- 03 Mar 2017 — X-ray left knee, weight-bearing: "Mild medial joint space narrowing. No fracture or loose body."
Onset Date
The most likely date of onset of this condition is 23 Jun 2008.
At that date the veteran was on warlike service in Afghanistan as an airfield defence guard, back on modified patrol duties in a hinged brace after his left knee injury of 16 March 2008. On 23 June 2008 he developed a new pattern of anteromedial knee pain with painful catching through mid-range flexion and pain after sitting in vehicles, which has persisted since.
This date is appropriate because his pre-deployment examination of 21 November 2007 recorded normal knees, the acute injury records of March and April 2008 describe only medial ligament and meniscal signs, and he presented the next day, 24 June 2008, with the palpable, tender medial plica and catching that characterise the chronic disorder. MRI in November 2008 and arthroscopy in March 2009 confirmed it. The date falls within his warlike service and within uninterrupted full-time service.
For the onset factors, the one year before onset runs from 23 Jun 2007 to 23 Jun 2008. The grade 2 medial collateral ligament sprain and the acute tear of the posterior horn of the medial meniscus were both sustained on 16 March 2008, three months before onset, on a loaded night patrol in Afghanistan.
For the worsening factors, the condition worsened from 05 July 2012, with recurrence of the plica, a new meniscal tear, persistent effusion and loss of the ability to run, documented on 14 February 2013. The one year before the worsening runs from 14 Feb 2012 to 14 Feb 2013. The partial anterior cruciate ligament sprain and the new acute medial meniscal tear were sustained on 05 July 2012, within that window, during warlike service in Afghanistan.
1. What is the formal diagnosis of the condition claimed above?
The formal diagnosis is Left Knee Plica Syndrome (ICD-10 M67.52), a chronic disorder of the left knee that followed a torn medial meniscus and a sprained medial collateral ligament. It is assessed under the Statements of Principles concerning internal derangement of the knee, Balance of Probabilities No. 8 of 2019 and Reasonable Hypothesis No. 7 of 2019, because the chronic disorder of the knee is due to the torn meniscus and stretched ligaments documented at injury, on MRI and at arthroscopy.
A plica is a fold of the synovial lining of the knee left over from fetal development. Most plicae cause no symptoms, but after a twisting injury, haemarthrosis or ligament and meniscal damage the medial plica can become inflamed, thickened and fibrotic. The stiffened band then snaps or rubs over the medial femoral condyle as the knee bends, causing anteromedial pain, painful clicking and catching, pain after prolonged sitting and recurrent swelling, and it can erode the underlying articular cartilage. Plica syndrome commonly coexists with the meniscal and ligament injuries that trigger it, and symptoms persist until the plica is resected.
The condition began on 23 June 2008, three months after a ligament sprain and acute meniscal tear of the left knee on warlike service in Afghanistan, was confirmed on MRI and at arthroscopy in 2008 and 2009, and worsened after a further ligament sprain and meniscal tear of the same knee in July 2012.
2. For each diagnosis identified, please also provide the following dates:
When did the veteran first experience symptoms attributable to this condition?
23 June 2008.
When did the veteran first present to a health / medical provider for this condition?
24 June 2008.
When was the condition confirmed / formally diagnosed?
12 November 2008.
When did the veteran first present to you (or your practice) for this condition?
06 May 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 surgeon on 12 November 2008 on the clinical findings of anteromedial pain, painful catching through mid-range flexion, a palpable tender medial band and a positive medial plica test, supported by MRI showing a thickened medial plica with synovitis, a healing grade 2 medial collateral ligament sprain and a tear of the posterior horn of the medial meniscus with acute bone bruising. Arthroscopy on 17 March 2009 confirmed a thickened, fibrosed medial plica impinging on the medial femoral condyle with chondral softening, an unstable meniscal tear and grade 1 medial collateral ligament laxity, and histology confirmed fibrotic synovium.
Because the chronic disorder of the knee is due to a torn meniscus and a torn or stretched collateral ligament, it falls within limb (a) of the Statement of Principles definition of internal derangement of the knee. The meniscal tear was acute and traumatic, with bone bruising on MRI, and not a degenerative tear excluded by limb (b). The worsening was confirmed by MRI on 14 February 2013 and repeat arthroscopy on 22 April 2013, which showed recurrent fibrotic plica, a partial anterior cruciate ligament tear, a new displaced radial meniscal tear and progression to grade 3 chondral change.
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.
Legislation: the clinical onset of this condition was on 23 June 2008, 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 and the Statements of Principles apply. The Balance of Probabilities instrument applies to peacetime service. The Reasonable Hypothesis instrument applies to the veteran's warlike service in Afghanistan in 2008, where the injury that caused the condition occurred, and in Afghanistan in 2012, where the injury that worsened it occurred. Factors 9(3) to 9(5) of each instrument apply to aggravation of the condition.
Each factor must be related to the person's relevant 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.
Balance of Probabilities — Statement of Principles concerning Internal Derangement of the Knee, No. 8 of 2019
Causative factors
Factor 9(1): having a sprain involving a ligament of the affected knee within the one year before the clinical onset of internal derangement of the knee; — MET
- On 16 March 2008, while carrying about 40 kilograms on a night patrol, the veteran stepped into an irrigation ditch and his left knee was forced into valgus and rotation. The medic recorded medial tenderness, early swelling and valgus laxity with a soft end point, and the role 2 review on 02 April 2008 recorded a grade 2 medial collateral ligament sprain with 5 to 7 millimetres of medial opening, later confirmed on MRI. The sprain occurred three months before onset, within the one year from 23 June 2007 to 23 June 2008, in the course of his duties during continuous full-time service.
Factor 9(2): having an acute meniscal tear of the affected knee within the one year before the clinical onset of internal derangement of the knee; — MET
- The same injury of 16 March 2008 caused an acute tear of the posterior horn of the left medial meniscus, with a pop, early swelling, a positive McMurray test and locking episodes recorded on 02 April 2008. MRI on 12 November 2008 showed the tear with bone bruising consistent with acute trauma, and arthroscopy on 17 March 2009 confirmed an unstable tear. The tear occurred within the one year before onset, from 23 June 2007 to 23 June 2008, during his duties.
Worsening factors
Factor 9(3): having a sprain involving a ligament of the affected knee within the one year before the clinical worsening of internal derangement of the knee; — MET
- On 05 July 2012 the veteran landed awkwardly on his left knee after jumping from a compound wall carrying 42 kilograms. The medical officer recorded a positive Lachman test with a firm end point and valgus pain, and MRI on 14 February 2013 showed a partial thickness anterior cruciate ligament tear. The sprain occurred within the one year before the worsening, from 14 February 2012 to 14 February 2013, in the course of his duties.
Factor 9(4): having an acute meniscal tear of the affected knee within the one year before the clinical worsening of internal derangement of the knee; — MET
- The 05 July 2012 injury locked the left knee, which had to be manipulated free, and MRI on 14 February 2013 and arthroscopy on 22 April 2013 showed a new displaced radial tear of the body of the medial meniscus. The acute tear occurred within the one year before the worsening, from 14 February 2012 to 14 February 2013, during his duties.
Factor 9(5): inability to obtain appropriate clinical management for internal derangement of the knee; — MET
- After both injuries the veteran could not obtain MRI or orthopaedic assessment in theatre. In 2008 he was returned to modified patrol duties in a brace after four weeks, and definitive investigation was delayed eight months to November 2008 and surgery to March 2009. In July 2012 the locked knee was manipulated by a medical officer and he continued patrolling in a brace for four months without imaging. The plica recurred and the chondral damage progressed during these delays. Under Brew v Repatriation Commission (1999) this is an inability to obtain appropriate clinical management.
Reasonable Hypothesis — Statement of Principles concerning Internal Derangement of the Knee, No. 7 of 2019
Causative factors
Factor 9(1): having a sprain involving a ligament of the affected knee within the one year before the clinical onset of internal derangement of the knee; — MET
- The grade 2 left medial collateral ligament sprain was sustained on 16 March 2008 on a loaded night foot patrol during warlike service in Afghanistan, when the veteran fell into an irrigation ditch. It occurred three months before onset, within the one year from 23 June 2007 to 23 June 2008, and was recorded by the medic on the day and at the role 2 facility on 02 April 2008.
Factor 9(2): having an acute meniscal tear of the affected knee within the one year before the clinical onset of internal derangement of the knee; — MET
- The acute posterior horn medial meniscal tear was sustained in the same fall on warlike service in Afghanistan on 16 March 2008, within the one year before onset, and was confirmed by MRI with acute bone bruising in November 2008 and at arthroscopy in March 2009.
Worsening factors
Factor 9(3): having a sprain involving a ligament of the affected knee within the one year before the clinical worsening of internal derangement of the knee; — MET
- The partial anterior cruciate ligament sprain of the left knee was sustained on 05 July 2012 when the veteran jumped from a compound wall under fire during warlike service in Afghanistan. It occurred within the one year before the worsening, from 14 February 2012 to 14 February 2013.
Factor 9(4): having an acute meniscal tear of the affected knee within the one year before the clinical worsening of internal derangement of the knee; — MET
- The new acute radial medial meniscal tear was sustained in the same incident on warlike service on 05 July 2012, presenting with a locked knee, and was confirmed on MRI on 14 February 2013 and at arthroscopy on 22 April 2013, within the one year before the worsening.
Factor 9(5): inability to obtain appropriate clinical management for internal derangement of the knee; — MET
- On warlike service in Afghanistan in both 2008 and 2012 no MRI or orthopaedic care was available in theatre, and operational manning required the veteran to keep patrolling in a brace on an injured knee. Investigation was delayed eight months after the first injury and seven months after the second, and the plica recurred and the cartilage damage progressed during those delays.
The % contribution of the causes is 100% and significant.
Sequelae
The left knee plica syndrome is a sequela of the medial collateral ligament sprain and acute meniscal tear sustained on warlike service on 16 March 2008, and its worsening is a sequela of the further ligament sprain and meniscal tear of 05 July 2012. The plica impingement and repeated meniscectomies have caused chondral damage of the medial femoral condyle, which is now progressing to early medial compartment osteoarthritis on weight-bearing X-ray of 03 March 2017. Altered gait has contributed to right knee and lower back pain recorded from 2015.
Unintended Consequence
Met. The return to modified patrol duties on an unassessed injured knee in 2008, and the manipulation and continued patrolling in a brace without imaging in 2012, were treatment decisions made by ADF health providers and paid for by the Commonwealth (section 6A of the DRCA and the equivalent provisions of the MRCA). The repeated loading of the knee under these arrangements contributed to the plica becoming fibrotic and to the progression of the cartilage damage.
Inability to Attain Appropriate Medical Management
MET. After both left knee injuries on warlike service in Afghanistan, in 2008 and 2012, the veteran could not obtain MRI, orthopaedic assessment or surgery in theatre and was kept on patrol duties in a brace. Definitive investigation was delayed eight months after the first injury and seven months after the second, during which the medial plica became fibrotic, recurred and eroded the underlying cartilage. Applying the objective and subjective tests in Brew v Repatriation Commission (Full Federal Court, 10 September 1999, Merkel J), the absence of specialist care in the operational area, combined with the operational requirement to keep working on the injured knee, amounted to an inability to obtain appropriate clinical management.
5. Please provide a Health Summary and a medication / prescribing history.
See attached report.
References
- 21 Nov 2007, Pre-deployment health assessment, Medical Officer, RAAF base health centre
- 16 Mar 2008, Patrol medic casualty record, Afghanistan
- 02 Apr 2008, Role 2 facility consultation, Medical Officer, Afghanistan
- 24 Jun 2008, Deployed health record, Medical Officer, Afghanistan
- 12 Nov 2008, MRI left knee report and orthopaedic consultation, Radiologist and Orthopaedic surgeon
- 17 Mar 2009, Operation report and histology, Orthopaedic surgeon and Pathologist
- 05 Jul 2012, Regimental aid post record, Medical Officer, Afghanistan
- 14 Feb 2013, MRI left knee report and orthopaedic review, Radiologist and Orthopaedic surgeon
- 22 Apr 2013, Operation report, Orthopaedic surgeon
- 03 Mar 2017, X-ray left knee report, Radiologist
- Statement of Principles concerning Internal Derangement of the Knee (Balance of Probabilities) No. 8 of 2019, Repatriation Medical Authority
- Statement of Principles concerning Internal Derangement of the Knee (Reasonable Hypothesis) No. 7 of 2019, Repatriation Medical Authority
