Signs and Symptoms of a Partial Tear of the Posterior Flexor Tendon
The most common signs and symptoms of a partial tear of the posterior flexor tendon include pain with active plantarflexion, pain with passive dorsiflexion, tenderness on palpation, and persistent symptoms despite conservative treatment. 1
Clinical Presentation
- Posteromedial ankle pain that is reproduced with active plantarflexion and passive dorsiflexion of the affected toe 1
- Tenderness with palpation at the anatomical location where the tendon passes (such as the knot of Henry for flexor hallucis longus) 2
- Pain with prolonged walking and running activities 2
- Sudden "pop" sensation may be reported in acute traumatic cases 3
- Progressive pain and dysfunction that persists despite conservative treatment 1
Mechanism of Injury
- Forced dorsiflexion injury during pivoting movements is a common mechanism 1
- Acute hyperextension of the metatarsophalangeal joint can lead to partial tears 2
- Chronic repetitive hyperextension movements can also cause partial tears over time 2
- Sports activities requiring quick directional changes (tennis, soccer) may predispose to these injuries 1, 4
Diagnostic Challenges
- Diagnosis is primarily based on history and physical examination findings 2
- Partial tears are more difficult to detect than complete ruptures because the tendon can maintain some tension 5
- Ultrasound has limitations in detecting partial tendon tears, with accuracy rates of only 66.7% for partial tears 6
- MRI is more accurate for identifying the type of tendon tear, with sensitivity and specificity of 76% and 50% respectively for partial tears, compared to ultrasound's 62.5% and 20.0% 6
Physical Examination Findings
- Decreased strength in the affected tendon's action (e.g., great toe plantarflexion for flexor hallucis longus) 1
- Pain on resisted testing of the involved tendon 1
- Tenderness along the course of the tendon, particularly at anatomical constraint points 2
- Possible mild swelling in the affected area 1
- No palpable gap (which would suggest complete rupture rather than partial tear) 7
Imaging Findings
- MRI may reveal fluid surrounding the affected tendon 1
- MRI can detect associated tenosynovitis and is superior for identifying partial tears 6
- Ultrasound may be useful for dynamic assessment but has limitations in detecting partial tears 6
- X-rays are not useful for direct visualization of tendon injuries but may help rule out associated fractures 7
Intraoperative Findings
- Longitudinal split tears are common in partial ruptures 1, 2
- Scar tissue and tenosynovitis are frequently present around the affected tendon 1
- Impingement of muscle fibers may be observed in chronic cases 1
- Surrounding soft tissue inflammation is typically present 1
Common Pitfalls in Diagnosis
- Partial tears are often misdiagnosed as tendinopathy or strain due to similar symptoms 6
- Noninvasive imaging studies including ultrasound may not be helpful in establishing the diagnosis in some cases 2
- Symptoms may persist for months despite conservative treatment before a definitive diagnosis is made 1
- The condition can be easily overlooked in cases with associated fractures due to the focus on the more obvious injury 5