Achilles tendon injuries are the most common tendon injury in the lower extremity. The majority of acute ruptures is seen amongst the “weekend warrior” in their fourth to fifth decade of life.
The Achilles tendon is derived from both the gastrocnemius muscle and the soleus muscle. 15cm proximal to the calcaneal insertion, the tendinous contributions become confluent as a single tendon. The Achilles tendon is enveloped by a paratenon that serves the function of allowing the tendon to glide freely as well as providing the majority of the blood supply to the tendon. Distally, the blood supply is mainly derived from osseous contributions. Because of the organization of the blood supply, there is a watershed area approximately 2-6cm from the insertion point on the calcaneus.
The Achilles tendon provides the mechanism for plantarflexion of the ankle. Contraction of the gastrocnemius/soleus complex provides the force necessary to generate toe-off during the late stance phase of the gait cycle. It additionally functions in an eccentric manner to prevent excessive dorsiflexion and to prevent forward lurching during the gait cycle. As is the case with all tendons, the viscoelastic properties are non-linear. This allows the Achilles tendon to become stiffer as force is applied more rapidly. The biomechanical strength of the tendon decreases with senescence which accounts for the increased incidence of Achilles tendon ruptures in the middle aged population.
A number of risk factors have been identified in association with Achilles tendon ruptures. While certain medications (fluoroquinolones, corticosteroids), medical conditions (renal insufficiency, autoimmune diseases, arteriosclerosis, hyperuricemia, genetic disorders of collagen), and activities have all been implicated, ruptures of the Achilles tendon are most likely multi-factorial.
The majority of Achilles tendon ruptures occur during injuries sustained while performing athletic activity. Most of those sustaining ruptures are middle-aged episodic athletes termed weekend warriors.
While the vast majority of injuries are acute, there is a small group – up to 15% – who experience prodromal symptoms of pain, swelling, and stiffness prior to rupturing their Achilles tendon.
The exact mechanism for injury usually falls into one of three patterns. The most common is that of forceful plantarflexion with the knee extended such as seen in sprinting and jumping activities. The typical presentation is that of a palpable/audible pop or the sensation of being struck in the back of the lower leg.
After this sensation patients commonly complain about weakness with push-off. Pain scales are variable amongst patients sustaining Achilles tendon ruptures and are not reliable in the history of an acute rupture. Sudden unexpected dorsiflexion of the ankle as seen in falling down stairs or slipping into a hole is also commonly reported. The least common mechanism reported is that of violent dorsiflexion of a plantarflexed ankle. This is usually related to falls from a height.
The optimal treatment of Achilles tendon ruptures remains controversial. While both nonoperative and surgical interventions have been advocated, both treatments offer advantages and potential complications. Each case should be evaluated individually with the overall health, activity level, and expectations of the patient carefully weighed with the potential benefits and risks of the treatment modality decided upon.
Non operative treatment remains a viable option for those choosing to avoid the risks of surgery or in those patients who are not suitable surgical candidates. Patients who undergo nonoperative treatment avoid the risks associated with surgery. This includes wound problems, nerve damage, and the inherent risks of surgery in general. Numerous studies have looked at the rates of re-rupture in patients undergoing non-operative treatment. Recent studies demonstrate a re-rupture rate approximately three times that of patients treated with surgery. However, there is conflicting data on re-rupture rates when an early range of motion protocol is employed. Certain studies have shown the rate of rupture to be nearly identical when patients treated non-operatively undergo an early range of motion protocol while others have shown no benefit of early range of motion compared with cast immobilization.
For more information regarding surgical management, please click here* (hyperlink to treatment page regarding achilles tendon repair)