Achilles tendon anatomy comprises the confluences of fibers from gastrocnemius and soleus which is a strong supporting tendon in erect.
Anatomy
Gastrocnemius and soleus muscle:- Confluence of fibers:- Achilles tendon is strongest and an average of 15 cm in length
Towards its insertion on the posterior tuberosity of the calcaneus, the tendon fibers twist in orientation by 90°
Horse shoe-shaped retro-calcaneal bursa is located deep and proximal to Achilles tendon insertion on Os-Calcis
It lacks a true synovial sheath, instead enveloped by thin membranous paratenon.
An important watershed region of relative hypovascularity exists approximately 2-6 cm proximal to the calcaneal insertion which is commonly involved in the lesion of the Achilles tendon
Blood Supply of the tendon
1. Musculo-tendinous junctions
2. Surrounding connecting tissues
3. Bone tendon units
Vascular supply is disputably precarious in mid-portion of 2-6 cm from the insertion of tendon and skin directly posterior to the tendon is relatively sparely supplied.
Etiology of Achilles tendon rupture
- Collagen disorders
- Inflammatory and autoimmune mechanisms
- Degenerative and repetitive trauma
- Drugs ( corticosteroids, fluoroquinolones)
- Exercise-induced hyperthermia
- Ischemic injury to the tendon
- Mechanical theory: eccentric loading + inefficient plantaris
Investigations
Most specific and sensitive: MRI
Plain X-ray
Loss of posterior border of Kager’s triangle (fat-filled triangular space in front of tendon Achilles) or complete disappearance
Toygar Sign:- Measurement of angle of the posterior skin surface on lateral view: increases to 130°-150°
Classifications
Myerson’s classification
Type 1 defect: 1-2 cm long
End to End repair, Post compartment fasciotomy
Type 2 defect: 2-5 cm long
V-Y lengthening with/out tendon transfer
Type 3 defect: >5 cm long
Tendon transfer + V-Y advancement + Augmentation
Acute Tendon Rupture
All eccentric contraction of the gastrocnemius-soleus complex during sudden/violent dorsiflexion of the plantarflexed foot. It generally gets ruptured in the watershed area.
Notice sudden, painful pop or snap in the calf during recreational activity or exercises that lead to immediate pain, weakness, and alteration of gait
Physical Examination
- Palpable discontinuity/ defect in rupture site
- Thompson test (+)
- Detectable weakness in palmer flexion compared to normal
See also: Foot and ankle examination
Treatment Options
Nonoperative treatment
Optimal treatment is both documented in the nonoperative and operative treatment
POP cast immobilization in plantar flexion for 4 weeks
Followed by exchange casting or splinting to keep the ankle immobilized in the neutral position for 4 more weeks
Operative treatment
Open End to End Repair:
- Krakow’s
- Bunnell
- Kessler’s type suture
Augmentation is done by
- Fascial turndown flaps (gastrocnemius aponeurotic flap)
- Tendon transfer
- Allografts/synthetic grafts
Percutaneous/ Mini open technique
Postoperatively non-weight bearing plaster immobilization is applied
Rupture is common in:
- Native Achilles tendons: Rich in type I collagen
- Healing tendons: Rich in type III collagens with poorly organized, weaknesses and less resistance to stretch
Chronic/Neglected Tendon rupture
Injury duration (4 – 10 weeks)
Palpable defects are commonly appreciable in acute rupture and are either less apparent or absent due to fibrosis
Thompson weakness test (-)
History of trauma, plantar flexion weakness + antalgic gait
Investigation
USG:- Hypoechoic area
MRI:- Extend of rupture and condition of tendon stumps
Treatment Options
Non-Operative Management
Rarely indicated especially in such patients:
- Without functional deficits
- Significant risk of wound complications
- Poor surgical candidates
Operative treatment
Primary end-to-end repair is rarely possible due to retracted tendons
( if the defect is < 3cm following debridement and is less than 12 weeks old direct repair may be possible)
If tendon gap is >3 cm
- Local tissue transfer
- Tissue augmentation
- Synthetic biomaterials +/- allografts
Local tissue transfer
Flexor hallucis longus (FHL) tendon is used as it is a long, reliable tendon, source stronger than either peroneal or FDL tendons.
FHL is near to FDL tendon making local transfer technically easier
Other option: Peroneus brevis
Tissue augmentation
Medial and lateral aponeurotic fascial turndown flaps can be done
Other sources:
- Plantaris
- V-Y advancement of the gastrocnemius-soleus complex aponeurosis
- Fascia lata grafting
Synthetics Biomaterials
- Carbon fibers
- Composite carbon fibers/ absorbable polymers
- Polymers type
- Mesh
Allografts
Large defect non-amendable to tendon transfer
Role of plantaris muscle in mid-portion Achilles tendinopathy
Origin: Lateral supracondylar ridge
Insertion: Posterior calcaneus via calcaneal tendon
Action: weakly assist gastric in plantar flexing ankle and flexing knee
Runs in the inner part of the entire calf Resistant cases of Achilles tendinopathy are associated with plantaris tendon involvement
