Knee Rotary Instability

Definition/Description

Rotational instability of the knee was observed as overrotation of the tibia relative to the femur. There are various types of rotational instability, but most studies have focused on the influence of posterolateral horn structure and its impact on rotational instability. hurt to The posterolateral corner (PLC) can lead to posterolateral rotational instability (PLRI) of the knee joint, which is a pathological instability caused by external rotation forces on the knee joint [1] or direct impact on the knee joint. joint, anteromedial knee joint caused by posterolateral subluxation of the tibia. [2] Rotational instability often occurs with ligamentous injury and is therefore difficult to detect/diagnose. [3]

Epidemiology/Etiology

• Isolated injuries of PLC have been reported to account for only 1.6% of all acute ligamentous injuries of the knee [4]
• In studies examining acute and chronic PLC injuries, 43% to 80% of patients reported concurrent ligamentous knee injuries. [5]
• PLC injuries were present in 68% of cases and in 5 of 7 patients with medial tibial plateau fractures.
• In more than 15% of cases, ACL reconstruction results in persistent pivot shift. The main reason for graft failure is the presence of unrecognized and therefore untreated PLRI. [6] [2]
• Diagnosing PLRI is difficult because it occurs rarely and develops slowly. In one study, 34 (50%) patients had no PLRI at initial diagnosis. [3]
• The mechanisms of injury reported in one study were: Traffic accidents (55%) Physical activity (30%) Mistakes/falls/other activities (15%)[3]

Characteristics/Clinical Presentation

Patients with rotational instability of the knee typically present with joint line tenderness and swelling of the posterolateral corner of the knee. Neurologic symptoms such as Numbness and weakness and paresthesias. Many patients with rotational instability of the knee report yielding or knee flexion during the stance phase of gate and rotational or twisting motions. Some patients respond without provocation or only just standing. (Ferarri) Standing posture can exhibit genu varus, while the stance phase of gait can exhibit hyperextended varus thrust. If patients experience this, they may try to walk, keeping their knees slightly bent while walking to avoid it. [7]

Differential Diagnosis

Damage to:

• ACL
• PCL
• MCL
• LCL
• Posteriolateral Corner
• Avulsion Fracture

Or any combination of the above.

Relevant Anatomy

Screenshot from GoogleBody

The posterolateral compartment (PLC) can be described as consisting of 5 structures (2 muscles and 3 ligaments); lateral head of gastrocnemius, popliteus, popliteal ligament, lateral collateral ligament (LCL), and the arcuate-peroneal ligament complex. This The biceps femoris tendon and iliotibial band also contribute to the stability of the knee PLC and can be damaged by injuries to this area.

PLC was used as the primary constraint for varus and supination forces, while PCL was used as a secondary constraint. The LCL plays the largest role in resisting varus stress, while the other components of the PLC play a greater role in resisting external rotation on the outside of the joint Tibia on femur. In particular the popliteus and the popliteal ligament have been shown to be the most important structures in resisting external rotation. [7]

Interruption of the PLC with an intact PCL resulted in increased knee varus and external rotation, most pronounced at 30° of knee flexion, whereas interruption of the PCL with an intact PLC resulted in increased posterior tibial translation, most pronounced at 90° of knee flexion. Disruption of the PLC and PCL results in increased varus, external rotation, and posterior translation at all angles of knee flexion [7].

Rotational Instability Primary Restraint Test AMRI (Anteromedial Rotational Instability) PMC which includes Medial Meniscal Posterior Corner POL Semimembranous Dilation Coronary Ligament OPLSlocum Test ALRI (Anterolateral Rotational Instability) ACL and MCL Pivot Offset Test Front Drawer Test Jerk Test HughstonLosee test SlocumNoyes test Lateral test / flexion rotation drawer test PMRI (Postero-medial Rotatory Instability) medial capsular ligament tibial collateral ligament POLACLPLRI (Postero-Lateral Rotatory Instability) PLC which includes LCL Arcuate ligament complex fabellofibular ligament Posterolateral capsule dial test (prone external rotation test) posterolateral drawer test (PLD test) reverse pivot shift test external rotation reverse flexion test posterolateral external rotation test

Examination

Neurological examination: pay special attention to the common peroneal nerve

Check blood supply for possible arterial rupture [7]

Special Tests:[3]

  [8]

Dial Test: 30* Knee Flexion Tibial External Rotation

Dial Test Video Courtesy of Clinically Relevant

• If testing for neutral tibial positioning in supine or prone position, look for posterior sag and apply anterior force.

Reverse Pivot Test: Original Pivot

Reverse Pivot Shift Test Video by Clinically Relevant

• (+) Tests for knee subluxation in proximal tibial flexion and posterior sag
• False positive rate- 35%

External Rotation Recurvatum Test

• (+) Tests tibial hyperextension external rotation and tibial varus

Posterolateral Drawer Test

• 15* Externally rotated PL translation significantly increased

Varus Stress Test

Inversion Stress Test Video by Clinically Relevant

The following findings were observed in the video above;

(+) Dial test showing Ext Rot and Lateral Tibial Subluxation

(+) Posterior drawer test

(+) Varus test

Imaging (photos used from Ricchetti)[7]

Standard x-rays of the knee can show a number of findings suggestive of acute PLC injury, including abnormal widening of the lateral joint space, avulsion fracture of the tip of the fibula or fracture of the capitellum, avulsion fracture of the Gerdy tuberosity in the iliotibial band, tibial platform damage Fractures and even Segond’s fractures. [7]

Although Segond fractures usually occur with ACL tears, they can also occur in isolated PLC injuries. Recent studies have shown that T1- or T2-weighted oblique coronal images through the knee joint and including the entire fibular head and styloid process provide the best visualization Individual structure of the PLC. [7]

Magnetic resonance imaging will also detect associated injuries, including ACL and PCL avulsion fractures and bony contusions, which typically occur in the medial femoral condyle or medial tibial plateau.

Outcome Measures

The same measures used during the examination can be used postoperatively to test for knee instability. Additionally, you can observe the tibial ER during gait and collect subjective information from patients such as whether the number of yields has decreased and their overall stability their knees.

Diagnosis

There is no single authoritative tool for diagnosing posterolateral corner injuries. [3]

Grade 1:

• 5-10* difference in tibial external rotation without varus instability [2]

Grade 2:

• ER increase >10* difference or posterolateral tibial plateau subluxation with grade 0-2 varus instability [2]

Grade3:

• External tibial rotation >10*difference/s solid endpoint, grade 3 varus instability due to LCL injury [2]

Medical Management[1][9][10][11]

Knee rotational instability is common with cruciate ligament injuries. With either type of damage, it’s important to address instability by rebuilding the PLC at the same time. Reconstruction of the ACL and PCL alone is insufficient to provide rotational stability. reconstructed PLC is necessary to reset the knee to a mode close to physiological relaxation. Furthermore, the PFL and PT had similar in situ forces, raising the idea that the PLC component might play an equally important role in restoring knee stability. Over time, this stress from lack of stability can lead to prolonged Laxity and increased force on the ligament graft lead to graft failure. It has been suggested several times that this instability is actually a major cause of graft failure. It has been found that rebuilding the PLC is best done at the same time as rebuilding the PCL and ACL.

Management according to PLC Grade:[7]

• Grade III almost always require surgery.
• Grade II can be treated nonoperatively. More severe grade II injuries or those associated with cruciate ligament tears or tibial plateau fractures should be treated surgically.
• Grade I is treated nonoperatively with good results.

Surgery

[12]

If the patient is stable, surgery should be performed within 3 weeks of injury to allow initial repair of the PLC. [7]

Type

Reconstruction rather than repair is most common in patients with posterolateral tears and injuries. [13] Reconstructive procedures can again be divided into those that attempt to restore the normal anatomy of the PLC and those that stabilize the PLC by tightening specific non-anatomical Structure [7] is working on the best way to rebuild PLCs.

Grafts

Autografts of the hamstring muscles, especially the long head of the biceps femoris tendon, have been shown to be effective. [9]

Other grafts being researched:[7]

• Achilles tendon allograft
• Anterior or posterior tibial tendon allograft
• Patellar tendon allograft or autograft
• Iliotibial band allograft or autograft

Procedures

A modified version of Larson’s technique called the modified posterolateral corner sling is often used. The most important structures for PLC reconstruction are the popliteal tendon LCL, especially the popliteal ligament. [14]

The two common techniques:[9]

1. across the outside of the tibia.
2. A tunnel through the fibular head and a 1 cm anterolateral epicondyle tunnel are medial through the tendon secured laterally with bioabsorbable screws.

Fibular head tunnels have shown better results than tibial tunnels.

Advantages:

• Short operation time and fewer surgical complications
• Better rotational stability
• Better isometricity

Complications:

• Fibular head fracture
• Fibular nerve injury

General complications:[7]

• Wound problems such as infection or hematoma formation
• Postoperative knee stiffness (usually loss of flexion)
• Failure of the repair or reconstruction
• Hamstring weakness (especially during biceps tendon surgery)
• Hardware irritation

Physical Therapy Management

It has been shown that weight-bearing protection of the extremity is usually necessary for the first 2 weeks, followed by a gradual rehabilitation program. Rehabilitation should include quadriceps strengthening and progressive resistance exercises with protected range of motion Activities [7] Physical therapy should focus on injury treatment. The physical therapist’s knowledge and the patient’s performance should be used to determine where the patient should start and how quickly they should proceed. Exercise should start with basic muscle strengthening, Then move on to higher levels of sport-specific training. [7]

Historically, open-chain exercises were thought to create additional shear forces, but it has been shown that open-chain exercises can lead to greater quadriceps strength gains compared to closed-chain exercises.

• Opened Chain Exercises:

1. Knee Extensions
2. Active knee flexion/extension with weight and/or resistance
3. Quad Sets

Despite the proven benefits of open-chain exercises, most time should be spent on closed-chain exercises because they provide proprioceptive input and proper co-contraction of antagonist and agonist muscles. Additionally, it can help improve strength function and Stability of upper and lower joints.

• Closed Chain Exercises:

1. Squats
2. Lunges
3. Single Leg Squats
4. Stair Climbing
5. Biking

Perturbation exercises help provide joint protection, improve knee kinematics and neuromuscular training. [15] Exercises that can be performed are: single-leg stances and squats double-leg movements and lunges. These should be performed on surfaces that need to be created by the patient themselves Stablize.

• Surfaces that can be used:[16][15]

1. Baps board
2. Trampoline
3. Rockerboard
4. Rollerboard/Platform

All of this should start from front to back, medial to lateral, and work through diagonal and rotational movements. Other issues that can be addressed are hip and ankle muscular braces and taping, which will help provide stability throughout the lower body. [7]

Key Research

Acute and chronic treatment of posterolateral corner injury of knee joint

Ricchetti E Sennett B Huffman G. Acute and Chronic Management of Posterolateral Corner Injuries of the Knee [Corrected] [Published Erratum in ORTHOPEDICS 2008 Jul;31(7):725]. Orthopedics [online serial]. 2008 May;31(5):479-490. Full text Ipswich MA available from: CINAHL Plus. visited July 13, 2011.

Clinical Bottom Line

Rotational instability of the knee is most commonly seen with concomitant ligamentous injuries. Diagnosis and treatment are difficult and often missed due to variable clinical presentation and lack of protocols. Both physical therapy and surgical intervention will depend on the severity of the location The injured structure as well as the patient’s capabilities and goals.