Knee dislocation is the displacement of the articular surfaces of the bones forming the knee joint relative to each other. Two types of dislocations can occur in the knee joint: displacement of the tibia relative to the femur and displacement of the patella relative to the tibia and femur. Pathology is manifested by sharp pain, swelling and deformation of the injury zone. Movements in the joint are impossible. Treatment – immediate reduction followed by immobilization. With dislocations of the tibia, reconstructive operations are often required in the long term.
ICD 10
S83.0 S83.1
Meaning
Knee dislocation is a pathological condition in which the articular surfaces of the bones shift and cease to be congruent. This term in traumatology and orthopedics means two types of dislocations that differ significantly in severity: dislocation of the tibia and dislocation of the patella. Dislocations of the tibia occur extremely rarely, are the result of a significant traumatic impact and often entail severe long-term consequences (arthrosis). Dislocation of the patella is a fairly common injury, the prognosis for this pathology is favorable.
Causes
Knee dislocations can be acquired (traumatic) or congenital. The cause of traumatic dislocation of the tibia can be natural or industrial disasters, road accidents, falling from a height, etc. Combinations with other lesions are not uncommon: fractures of the bones of the skeleton, TBI, damage to the chest, injury to the genitourinary organs. The type of dislocation of the tibia is determined by the mechanism of injury:
- Anterior dislocation occurs due to forcible overextension of the knee with a fixed lower leg or direct rough impact on the lower part of the thigh in front or on the upper part of the lower leg from behind.
- A posterior dislocation is formed as a result of forced pressure or a strong push from behind on the lower thigh or from the front on the upper leg.
- External and internal dislocations develop with intense sharp pressure on the lateral surfaces of the thigh with fixed lower extremities or, conversely, on the lateral parts of the lower leg with a fixed hip.
The reason for the acquired dislocation of the patella, as a rule, is a fall or a side blow to the knee, combinations with other injuries are observed infrequently. Congenital dislocations of the knee are rare, due to adverse effects at the stage of embryogenesis.
Pathogenesis
The femur and tibia are connected to each other, forming a knee joint, which has a capsule and is strengthened by powerful ligaments. Between the articular ends of the bones are elastic pads – menisci. A significant displacement of the articular surfaces of bones is possible only with high-energy injuries accompanied by a violation of the integrity of many elements of the joint, therefore knee dislocations are combined with ligament ruptures, meniscus injuries, fractures of the epiphyseal and metaphyseal zones.
The patella is located in front, is a sesamoid bone (the ossified part of the tendon), does not connect with other bones, is fixed from above by the tendons of the quadriceps femoris muscle, from below by its own patellar ligament. With dislocation, the patella can move sideways (inside or outside), turn around its axis or wedge into the articular gap between the tibia and femur. The main structures of the knee often remain intact or are slightly damaged.
Symptoms
Anterior knee dislocation
It is considered the most common dislocation of the tibia. Accompanied by a rupture of the cruciate ligaments and the posterior parts of the articular bag. Often there is also a rupture of the lateral, median ligaments. Compression or damage of popliteal vessels, fibular and tibial nerves is possible. If the vessels are damaged, the lower leg is pale, cold, cyanotic, the pulse is weakened or not determined. With nerve damage, sensitivity disorders and paralysis are possible.
The patient notes intense pain in the affected area. The knee is swollen, sharply deformed, hematomas and hemorrhages are detected during examination. Active movements are impossible, when attempting passive movements, a spring resistance is determined. Support is impossible. With complete dislocations of the leg in a state of extension or slight flexion, a shortening of the limb is detected.
With incomplete dislocations, the limb is in a position of slight flexion, there is no shortening. There is a significant increase in the knee in the anteroposterior direction. The tuberosity and condyles of the tibia protrude along the anterior surface, the condyles of the femur stand on the posterior surface. The patella occupies an oblique position and “lies down” on the articular surface of the tibia.
Posterior dislocation of the knee
It is accompanied by damage to the cruciate ligaments, often the lateral and median ligaments are also torn. It is possible to tear off its own patellar ligament at the place of attachment (in the area of tuberosity of the tibia). The patient complains of unbearable pain. In the area of damage, significant swelling, cyanosis, areas of hemorrhage, pronounced deformation are determined. There are no movements in the knee, the supporting function of the limb is lost.
With a complete dislocation, the leg is in the extension position, shortened. With incomplete dislocation, the lower limb is bent, there is no shortening. The condyles of the femur will stand in front, the articular surface of the tibia will stand behind. The patella is located obliquely and lies on the condyles of the thigh. Nerve and vascular injuries are often observed, manifested by appropriate symptoms.
Lateral dislocations of the knee
Internal and external knee dislocations are rare and usually incomplete. Accompanied by a rupture of the lateral and median ligament. The knee is deformed, edematous, sharply painful. The impossibility of support and movement is noted. The leg is in the flexion position, the foot is turned. The patella shifts to the side opposite to the dislocation and occupies an oblique-transverse position.
Dislocation of the patella
The damage is accompanied by sharp pain. The knee joint is swollen, slightly bent. Deformity is detected in the anterior sections. The most common is the variant in which the patella is displaced outward (external dislocation), displacement inward and wedging between other bones are less common. The volume of the knee is increased, as a rule, hemarthrosis is determined. There are no active movements, passive ones are significantly limited. Palpation – patella is displaced, feeling the area of damage is sharply painful.
Congenital dislocations of the knee
This type of congenital anomaly of the joint is detected at birth or at an early age. Dislocation of the patella is more common in boys, combined with underdevelopment of the patella and the external condyle, other anomalies of the knee joint may be detected. The main manifestations are unsteadiness of gait, instability and rapid fatigue of the limb.
Congenital dislocation of the lower leg often occurs from two sides, at the same time, underdevelopment of the knee and ankle joints is revealed. Hypoplasia or aplasia of the tibia is possible. Without surgical treatment, the pathology worsens with age, congenital dislocations of the patella and tibia cause the development of severe arthrosis.
Complications
Early complications of patellar dislocation are rare. In the long term, sometimes there is instability, habitual dislocations. The displacement of the tibia is accompanied by massive damage to other structures, with such dislocations of the knee, a rupture of ligaments is always detected, often a violation of the integrity of blood vessels and nerve trunks is revealed. After recovery, there is a possibility of the formation of joint instability, early development of progressive gonarthrosis.
Diagnostics
Diagnostics is performed in the emergency room, the nature of the damage is determined by the results of the examination of the traumatologist and the data of additional studies. The examination plan for knee dislocations includes:
- External inspection. Visual recognition of tibia dislocations is not difficult due to a gross violation of the contours of the joint, pathognomonic for dislocations lack of movement against the background of spring resistance. The displacement of the patella is also well recognized by visual inspection due to the deformation of the front of the knee.
- Knee x-ray. It is the main instrumental method of research. According to the radiographs, the type (anterior, posterior, lateral) and severity (complete, incomplete) of the dislocation of the tibia are determined, concomitant fractures are diagnosed. In case of dislocations of the patella, the option of displacement is specified in the pictures (sideways, with a turn, with a wedge).
- Other visualization techniques. They are among the auxiliary ones, used if necessary to clarify the nature and severity of soft tissue damage and choose the optimal treatment tactics. To assess the condition of the capsule and ligaments, MRI and ultrasound of the knee can be prescribed.
- Arthroscopic examination. Arthroscopy is not used at the initial examination stage. It can be prescribed after reduction if the results of conservative treatment are ineffective and surgical intervention planning is necessary.
If vascular damage is suspected, a vascular surgeon’s consultation is necessary, with possible compression or rupture of nerves, a consultation of a neurosurgeon or neurologist is required.
Treatment
First aid
At the first aid stage, the victim’s leg is fixed with a splint from the foot to the hip joint in the position in which it is located. Attempts to forcibly change the position of the limb are strictly prohibited, as they can aggravate the injury. The patient is given an analgesic drug, cold is applied to the knee area to reduce swelling, and immediate delivery to a specialized medical institution is organized.
Treatment of patellar dislocation
The management of the patient is usually conservative. An orthopedic traumatologist performs patellar reduction under local anesthesia (anesthesia is used in children), in the presence of hemarthrosis, performs a puncture of the knee. Then a plaster splint is applied and a control radiography is performed. Immobilization is continued for 4-6 weeks, the patient is prescribed UHF and massage.
In some cases, especially with early termination of immobilization, relapses are possible, therefore, in recent years, to improve long-term results, active treatment tactics are increasingly used not only with the development of habitual dislocations, but also prophylactically. Surgical techniques include:
- Arthroscopic stabilization. It is a minimally invasive intervention, performed with external dislocations at an early stage of treatment to prevent relapses, subluxations and instability of the joint. It includes a transosseous suture of the medial ligament in combination with laterorelesis (dissection) of the lateral ligament.
- Open commit. It is performed with the usual dislocations of the knee using a traditional incision. It provides for the fixation of the patella by stitching a muscle flap, a section of the fascia of the quadriceps muscle or a joint capsule.
In the postoperative period, bandages are performed, antibiotic therapy is prescribed, rehabilitation measures are carried out.
Treatment of tibia dislocation
It is carried out in the conditions of the traumatology department. To prevent the consequences of possible damage to blood vessels and nerves, immediate reduction is necessary. The manipulation is performed under spinal anesthesia or general anesthesia. Then a puncture of the joint is performed, a plaster cast is applied and mandatory X-ray monitoring is carried out. The following surgical interventions can be performed:
In case of rupture of blood vessels, nerves, complicating knee dislocation, surgical treatment is indicated. It is possible to suture a nerve with the involvement of a neurosurgeon, suture or ligation of an artery with the participation of a vascular surgeon.
Due to significant damage to the handbag-ligamentous apparatus, the outcome of a dislocation of the tibia often becomes a dangling knee, so many specialists from the very beginning choose active surgical tactics, carrying out not closed, but open reduction and stitching of ligaments.
After the knee dislocation is corrected, the patient is sent to UHF. Plaster is preserved for 4-6 weeks, then walking is allowed. In the recovery period, physical therapy and massage are prescribed.
Treatment of congenital dislocations
The main method of treatment is surgical operations. The choice of the technique and the age of the intervention are determined by the nature of the dislocation:
- Dislocations of the patella. Operations are performed in childhood or adolescence. The method involves moving one’s own ligament with its subsequent fixation.
- Dislocations of the lower leg. Surgical correction is recommended to be carried out after the age of 2 years. The scope of interventions varies greatly, depends on the features of pathology, may include bone grafting, ligament grafting and other manipulations.
Forecast
The outcome is determined by the type of knee dislocation. After dislocations of tibia, relapses rarely occur. Unsteadiness of gait and limitation of the volume of movements may be detected. Instability of the joint is often observed, early development of deforming arthrosis is possible. Many patients require reconstructive ligament surgeries to fully restore their ability to work.
In case of patellar injuries, the prognosis is considered favorable, but in some patients, after recovery, a habitual dislocation is formed that requires surgical treatment. The completeness of the restoration of limb functions in congenital malformations is determined by the severity of the anomaly, the timeliness and adequacy of treatment.
Prevention
Measures to prevent traumatic dislocations of the knee include compliance with safety regulations at work, following the rules of the road, prevention of domestic and sports injuries. Prevention of congenital dislocations has not been developed.
Literature
- Prearthrotomy diagnostic evaluation of the knee: review of 100 cases diagnosed by arthrography and arthroscopy. Levinsohn EM, Baker BE. AJR Am J Roentgenol. 1980 Jan;134(1):107-11 link
- Traumatic dislocation of the knee: a review of the literature. Ghalambor N, Vangsness CT Jr. Bull Hosp Jt Dis. 1995;54(1):19-24. link
- Traumatic dislocation of the knee joint. A study of eighteen cases. Meyers MH, Harvey JP Jr. J Bone Joint Surg Am. 1971 Jan;53(1):16-29. link
- Reconstruction of the athlete’s injured knee: anatomy, diagnosis, treatment. Collins HR. Orthop Clin North Am. 1971 Mar;2(1):207-30. link