PTFJ & Lateral Knee Pain: The Science Skip to main content

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PTFJ & Lateral Knee Pain: The Science


El Paso, TX. Chiropractor, Dr. Alexander Jimenez looks at the role of the proximal tibiofibular joint in the etiology of lateral knee pain.

Pain about the lateral aspect of the knee is usually attributed to ailments such as iliotibial band compression/friction syndrome, lateral meniscus lesions and patellofemoral pain, and the encouraging patella lateral retinaculum. In the absence of those conditions, other less frequent presentations could be sinus plica, fabella syndrome, biceps tendinosis, or popliteus tendinosis.

One of the more unusual kinds of lateral knee pain in the athlete might be the proximal tibiofibular joint (PTFJ) -- either as hypomobility or instability(1-4). This injury occurs in various sports involving twisting forces around the ankle and knee like football, wrestling, softball, gymnastics, long jumping, dancing, judo and skiing. The variety of symptoms it can cause, contain external knee pain (particularly on weight bearing), locking and 'popping' in the knee and also transient nerve symptoms. This makes this harm a significant one to recognize and speech, particularly in large demand athletes.

Anatomy Of The Proximal Tibiofibular Joint (PTFJ)

The PTFJ is an inherently stable ‘plane like’ joint on the posterolateral part the knee, and is stabilized by a host of primary and secondary stabilizers(5,6). The primary stabilizers (see figure 1 below) include(7):

  • Biceps femoris tendon
  • Lateral collateral ligament
  • The principal capsule and ligament associated with the joint.
  • The secondary stabilizers contain:
  • Arcuate ligament
  • Popliteofibular ligament
  • Popliteus muscle and tendon
These soft tissues work together to stabilize the PTFJ. Kinematic studies have suggested that the lateral collateral ligament serves as the major stabilizer of this PTFJ in extension(1,2). Because of the resistance supplied from the lateral collateral ligament, the majority of the joint injuries are thought to occur while the knee is in flexion. This may explain the association between multi-ligamentous knee injuries which occur in flexion and PTFJ disruptions.

The joint is surrounded by a fibrous capsule, which can be further strengthened by notable attachment ligaments which blend in the capsule. Posteriorly, it's a thick single band, which runs in an oblique direction from the head of the fibula to the rear of the lateral tibial plateau. This can be coated with the popliteus tendon. Furthermore, a single feeble band runs from the fibular head into the anterior element of the popliteus tendon. Anteriorly two or three bands run obliquely in the very front of the fibular head to the lateral condyle of the tibia(7).

A synovial membrane -- like that found inside the knee joint -- lines the interior surface of the capsule of the PTFJ. In 10 percent of the populace, this synovial space is continuous with that of the knee joint. The joint is closely connected with the frequent peroneal nerve, moving forwards by the popliteal fossa around the fibula head, and here it is vulnerable to injury. Such an injury to the nerve with injury to the PTFJ may cause foot fall and loss of sensation in parts of the feet and leg.

There are different anatomic variants of the PTFJ which can be classified into three types:

1. Type I includes PTFJs with a nearly
horizontal articular surface (less than 30° of inclination) and a surface area of less than 20mm(1,2).

2. Type II includes PTFJs with a large, elliptical surface, concave on the fibula, and frequently having a joint communication to the knee.

3. Type III includes PTFJs with a small articular surface (less than 15 mm) and a steep inclination (more than 30°)(8).

These anatomic variations have to be considered when treating patients with an injury to the PTFJ.

Biomechanics Of The PTFJ

The anatomy of the PTFJ directly relates to its functional stability. It can withstand stresses applied in either a longitudinal or axial manner. Roughly one-sixth of this static load applied in the ankle is transmitted across the fibula into the PTFJ(9,10). Thus, the primary functions of this PTFJ are as follows:
  • Dissipation of torsional stresses applied at the ankle
  • Dissipation of lateral tibial bending moments
  • Tensile, rather than compressive, weight bearing(1,2).
As the ankle dorsiflexes, the PTFJ receives a torsional stress via external rotation and anterior glide of the fibula(4,8). Thus, decreased mobility of the PTFJ may subsequently limit ankle dorsiflexion assortment of motion.

When the knee bends, the fibula moves anteriorly, and with knee expansion the fibula head moves posteriorly. It was found that with the knee bent, the mobility of the proximal fibula increased and the fibular head may be moved approximately 1 cm in both anterior and posterior directions. With the knee extended, the trip of the fibular head was minimal as a result of stabilizing character of the supporting soft tissues(1,2). There's also a slight upward movement of the fibula due to forced expansion of the malleolar mortise during maximal dorsiflexion of the ankle(11).

The shape and orientation of this PTFJ may also influence the way the PTFJ works. In a horizontal PTFJ, both articulating surfaces are both curved and planar, and their place provides some stability against displacement. From the oblique type of joint, the articulating surfaces are far more variable in place, configuration and inclination. Because this kind of joint is not as able to rotate and accommodate torsional stresses than a horizontal joint, it is thought to be more likely to dislocate.

PTFJ Dislocation

PTFJ dislocations have been classified as follows(1,2):
  • Type 1 (subluxation only)
  • Type 2 (anterolateral)
  • Type 3 (posteriosuperior)
  • Type 4 (superior)
Associated peroneal nerve injuries are more likely to be associated with types 2 and 3. The mechanism of injury was described as a surprising inversion and plantar flexion of the foot and ankle, with a simultaneous knee flexion and external rotation of the leg. For this reason, it is commonly related to lateral ankle injuries, and therefore usually related to a traumatic event in the athletic context. Normal mechanisms of injury would be twisting injuries, hard landings or slipping together with the knee flexed under the body.

Sports doctors should also be alert to subluxation of the joint (excessive forward to backward motion of the fibular head, causing symptoms), which is frequently related to ligamentous laxity.

The nature of the traumatic event dictates the manner in which the PTFJ will dislocate. Even though there are four types of dislocation, the usual person in sporting contexts is anterolateral (type 2). This, together with the external rotational torque of the tibia on the foot through twisting of the body, springs the head of the fibula outside cartilage. At this point, a violent contraction of the peroneal nerves, the extensor digitorum longus and the extensor hallucis longus (caused by abrupt inversion and plantar flexion of the foot), pulls the fibula forward.

Signs & Symptoms

Identification of the harm is generally based on clinical history and clinical suspicion. Because of the nature of this presentation, it's often mistaken for a meniscal injury. Common signs and symptoms which may alert a sports medicine practitioner to a PTFJ injury are as follows:

1. Outer-knee pain, which is aggravated by pressure over the fibular head.

2. Anterolateral prominence of the fibula head in type 2 injuries.

3. Usually minimal effusion.

4. Limited knee extension.

5. Crepitus (grinding) on knee movement

6. Pain on weight bearing.

7. Visible deformity.

8. Locking or popping.

9. Ankle movements provoking lateral knee pain.

10. Temporary peroneal nerve palsy (pins and needles on the outside of the leg). This is more likely in the athlete who suffers a type-2 anterolateral dislocation as the nerve courses close to the front of the fibula head.

Plain X-ray imaging is generally not helpful, but may show the subtle signs of increased interosseous distance and displacement of the fibula from its regular position. But a CT scan may be needed to verify the diagnosis(16, 17). The main abnormality is lateral displacement on the anteroposterior view, and possibly slight anterior or posterior displacement on the lateral view(18). It has been suggested that computed tomography of the knee could be proper in patients where this diagnosis is suspected, due to the poor analytical value of plain radiology (16). MRI has the benefit of revealing ligament injuries in addition to the dislocation.

Injury Management

Currently, there is not any definitive option for surgical treatment of severe dislocations of this PTFJ. The options are:

1. Closed reduction and immobilization in plaster cast.

2. Closed reduction without immobilizing.

3. Temporary operative stabilization of the joint and repair of the joint capsule.

4. Immediate joint fusion (arthrodesis).

5. Resection of the fibular head.

The treatment options also change with the pattern of dislocation. The management of type 1 and 2 injuries is reduction by anteroposterior pressure over the fibula head, together with the knee slightly flexed and the ankle everted. There is often an audible and/or palpable movement with rapid improvement in symptoms.

There's insufficient evidence to support or refute the use of immobilization after a decrease of a type 1 or 2 injury, although several previous case reports have recommended immobilization for varying periods together with the knee in extension or minor flexion for 2-3 months(1,2,19,20). It is controversial whether weight bearing ought to be performed after the process(21). It's more difficult to reduce type 3 and 4 accidents, and these can require open reduction and fixation. However attempting a closed reduction initially is an alternative. Several techniques have been described involving fixation and supplementing using a portion of the biceps femoris tendon(22, 23).

PTFJ injury is usually missed, and a number of individuals present with chronic lateral knee pain or joint uncertainty. Unrecognized dislocations often present with peroneal nerve symptoms like pins and needles in the leg or feet, or weakness of foot motions. There is absolutely no function for attempted closed reduction within this circumstance.

Surgical stabilization is needed in around 57 percent of late or recurrent instances because of persistent pain and chronic instability(1,2,24). Normal ligament reconstructions include iliotibial band or the biceps femoris tendon(25, 27-29). Resection of the fibular head is believed to affect knee stability and gait. The decision to eliminate hardware after arthrodesis remains contentious. It has been discovered that PTFJ arthrodesis with early screw removal at three to six months has got good results in athletes(30).

Conclusion

Injuries to the PTFJ are uncommon in the sporting knee. This injury type may manifest as instability and dislocation, or as a hypomobile joint following ankle sprains. Early identification and treatment are essential to enable prompt rehabilitation. Treatment options vary according to the time of injury, nature of injury and associated morbidity. A return to sport is possible after effective treatment.

References
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