Injuries of the knee extensor apparatus
Injuries in this location typically occur via two mechanisms: as a result of direct mechanical impact (trauma) or due to excessively abrupt contraction of the quadriceps femoris muscle (m. quadriceps femoris).
Regardless of the specific structure damaged, the patient exhibits pronounced pain and swelling in the knee region. A characteristic functional impairment is a decrease in muscle strength or the total inability to actively extend the leg at the knee (this sign is tested with the patient in a sitting position). In daily life, patients frequently complain of the leg involuntarily buckling while descending stairs.
In the early post-injury period, surgical management consists of suturing the torn tissues followed by limb immobilization for a period of 4 to 6 weeks. However, in neglected injuries, secondary scarring deformations develop, making primary repair unfeasible. In such situations, reconstructive surgery using the patient's own tissues or specialized synthetic materials is employed. Following these reconstructive procedures, a more prolonged immobilization in a brace is required — from 6 to 8 weeks. In the post-immobilization period, it is critically important to conduct physical therapy (PT) and physiotherapy aimed at progressively increasing the knee flexion range of motion and restoring quadriceps strength.
Differential diagnosis of knee injuries
To select the correct surgical strategy in the early period, it is necessary to clearly differentiate between a tear of the quadriceps tendon expansion and a rupture of the patellar ligament (ligamentum patellae).
Signs of quadriceps tendon injury:
- The localization of maximum pain, tissue depression, or decreased tone is determined strictly above the patella.
- The patella does not displace proximally upon muscle contraction; high riding of the patella is absent.
- There is hypermobility of the patella distally (in both directions).
- The distance between the patella and the tibial tuberosity remains unchanged during knee flexion.
- Surgical treatment: the injured structure is sutured and fixed to the superior pole of the patella.
Signs of patellar ligament injury:
- The zone of greatest tenderness and depression is located below the patella.
- Pathologically high riding of the patella is revealed, which is aggravated when attempting to contract the quadriceps muscle.
- Hypermobility of the patella is directed proximally (in both directions).
- Upon knee flexion, the distance from the patella to the tibial tuberosity pathologically increases.
- Surgical treatment: the ruptured ligament is sutured and anchored either to the inferior pole of the patella or directly to the tibial tuberosity (tuberositas tibiae). Percutaneous (closed) suturing is also an option.
Achilles (calcaneal) tendon ruptures
Injuries to the calcaneal tendon are divided into open (resulting from direct wounds) and closed. Closed ruptures traditionally occur against the background of pre-existing degenerative changes in the tendon tissue. The typical mechanism is a powerful, forced contraction of the triceps surae muscle at the time of strong resistance to a plantarflexor (e.g., during an abrupt jump or an awkward landing on the forefoot). Morphologically, the injury is characterized by severe fraying of the torn ends.
At the exact moment of injury, the individual feels a sharp, shooting pain and hears a distinct snap. Patients often describe this condition as the sensation of a heavy "blow with a stick" to the posterior aspect of the lower leg. At the same time, the ability to bear weight on the leg is usually preserved, but gait is severely impaired due to the pain syndrome and a critical drop in plantarflexion strength. An absolutely pathognomonic sign is the patient's inability to stand on tiptoe on the injured extremity.
Local inspection reveals specific tissue depression. In a complete rupture, it is bounded by the ends of the damaged tendon and becomes much more noticeable if the patient attempts to contract the calf muscle while weight-bearing on the forefoot. In a partial injury, the depression may be smoothed out, does not increase with muscle contraction, and part of the tendon that tightens during active movement can be palpated in the injury zone.
Briefly: answers to topical questions
What clinical tests are used for the physical diagnosis of an Achilles tendon rupture?
For the physical diagnosis of an Achilles tendon rupture, tests evaluating the plantarflexion function of the foot are used.
- Toe-stand test — the patient cannot stand on tiptoe on the injured leg (pathognomonic sign).
- Simmonds' (Thompson) test — the physician compresses the calf muscle laterally in the upper third of the leg in a patient lying prone or kneeling. Normally, spontaneous plantarflexion of the foot occurs, and its absence indicates a complete injury of the tendon or the triceps surae muscle.
What is the treatment strategy for a subcutaneous rupture of the extensor tendon at the level of the distal interphalangeal joint (mallet finger)?
In the early stages, a conservative treatment method is used, the optimal strategy of which is a combination of immobilization with percutaneous Kirschner wire fixation.
- Immobilization without a wire — a plaster cast is applied in the position of maximum extension of the terminal phalanx, or a Rozov splint is used for 6–8 weeks.
- Immobilization with a wire — transarticular fixation lasts 3–4 weeks, after which the wire is removed and active range-of-motion exercises are initiated.
If conservative therapy fails or in late presentations, surgical treatment is indicated — reconstruction of the tendinous-aponeurotic expansion using local tissues.
What are the clinical manifestations of the boutonnière finger deformity?
Clinically, the boutonnière deformity (Weinstein's double contracture) manifests as a characteristic forced position of the finger phalanges.
- Proximal interphalangeal joint — is in a state of flexion contracture (middle phalanx is flexed).
- Distal interphalangeal joint — is in a state of hyperextension (terminal phalanx is hyperextended).
When attempting active extension of the middle phalanx, the deformity only worsens. The pathology occurs because the joint slips between the displaced lateral bands of the tendon, and at the level of the middle phalanx, the extensor begins to act as a flexor.
For differential diagnosis of knee injuries: the localization of pain and depression directly points to the ruptured structure. ABOVE the patella — the muscle is injured (which is located superiorly), BELOW the patella — the ligament is injured (which attaches inferiorly).
What else to study on this topic
- Technique of percutaneous suturing for the patellar ligament
- Physiotherapy treatment regimens following prolonged immobilization
- Physical therapy (PT) protocols for quadriceps femoris rehabilitation
- Materials and autografts used for the reconstruction of neglected injuries
- Anatomic features of the plantaris muscle and its role in diagnostic errors
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