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Rupture of the patella ligament: causes, symptoms, diagnosis, treatment
Last reviewed: 05.07.2025
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ICD-10 code
S83.6 Sprain and rupture of other and unspecified elements of knee joint
What causes a patellar tendon tear?
Most often, a rupture of the patellar ligament occurs with a direct mechanism of injury.
Closed injuries of the ligamentous apparatus are in most cases the result of indirect violence - a movement that exceeds the functional capabilities of the joint. A distinction is made between sprains and ruptures of ligaments. Since sprains have already been considered, we will focus on ruptures.
Isolated closed ligament ruptures most often occur in the knee, ankle, and first metacarpophalangeal joints. Ligament injuries in other joints are usually accompanied by bone fractures and dislocations.
When one or more ligaments of the knee joint are torn, its supporting function is disrupted - instability and dislocation appear, which is referred to as “joint instability”.
Symptoms of a Patellar Ligament Tear
Patients complain of pain and instability in the knee joint.
Patellar ligament rupture classification
Ruptures of the patellar ligament can be partial or complete.
Based on the degree of morphofunctional disorders of all anatomical formations of the functional system of the knee joint, G.P. Kotelnikov identified three forms of its instability: compensated, subcompensated and decompensated.
- In patients with compensated posttraumatic instability of the knee joint, most qualitative indicators are usually close to the norm. Clinically, muscle atrophy is almost not detected, their strength is estimated at 5 points. Only the use of a device for detecting instability in the joint allows us to establish pathology. Arthroscopy helps to detect damage to specific anatomical structures. Biopsy and the study of functional and biomechanical examination indicators (electromyography, rheovasography, podography, etc.) indicate that the existing changes only slightly deviate from the norm.
- In patients with subcompensated joint instability, qualitative indicators are altered. Periodically, pain and crunching in the joint occur, and the thigh muscles atrophy. The difference in hip circumference reaches 3-4 cm. Instability manifests itself with significant loads and running. In half of the patients, instability is detected clinically, in almost all - with the help of special devices for diagnosing ligament rupture. The strength of the flexors and extensors of the lower leg is up to 4 points. X-rays show changes corresponding to gonarthrosis stage I - II. Additional research methods confirm the presence of pathology in the joint.
- In the decompensated form of instability, all indicators of clinical and morphofunctional examination significantly deviate from the norm. Patients complain of constant pain, instability in the knee joint even when walking, sensations of crunching, clicking, and the appearance of lameness. Some patients use a cane. During examination, sharp muscle atrophy with a decrease in strength of less than 4 points is revealed. Pathological mobility in the knee joint is clinically noted by all patients, so there is no need for additional devices to determine instability. X-ray and microscopic studies reveal changes in the joint characteristic of arthrosis of the II-III degree.
The proposed classification allows solving tactical problems in choosing the necessary treatment method.
[ Diagnosis of patellar ligament rupture
Anamnesis
The anamnesis indicates a corresponding injury.
Inspection and physical examination
On examination, swelling and bruising are found below the patella. When the quadriceps muscle of the thigh is strained, the tone of the patellar ligament is absent. The patella is located above the usual place. Movements in the knee joint are moderately limited due to pain, except for active flexion, which is absent - a positive "sticking heel" symptom.
Laboratory and instrumental studies
X-rays of the knee joint reveal a high position of the patella, and sometimes avulsion fractures of the tibial tuberosity.
Treatment of patellar ligament rupture
Conservative treatment of patellar ligament rupture
In case of incomplete rupture, conservative treatment of patellar ligament rupture is possible.
Surgical treatment of patellar ligament rupture
In case of complete ruptures, the ligaments are restored surgically using classic sutures or their combinations used for suturing tendons.
After the intervention, a circular plaster cast is applied from the inguinal fold to the tips of the fingers for 6-8 weeks. In case of old ruptures of the patellar ligament, auto- or alloplasty is used.
An 8-10 cm long incision is made in the projection of the patellar ligament. Old scar tissue is separated bluntly and sharply, and a bed for the graft is formed. Transverse canals are formed in the middle of the patella and the tibial tuberosity with an awl. The graft is taken from the broad fascia of the thigh on a “feeding leg”. It is carried out sequentially: from the outside inward through the patellar canal, then down through the canal in the tuberosity from the inside out, then up. The graft is stretched after the maximum lowering of the patella and sutured with the beginning of the graft at the entrance to the first canal. In the middle part, both portions of the graft are sutured together, immersed in the scar and in the remaining remnants of the ligament, and sutured above the graft.