Psoas impingement is a known complication following total hip replacement (THR) . This problem arises from mechanical irritation of the iliopsoas tendon (hip flexor), which often results in an inflammatory response. A crucial factor can be reduced anteversion of the acetabular implant, which restricts the range of motion of the hip flexor muscle.

What is anteversion?

Anteversion ) . It is crucial for ensuring the mobility and stability of the artificial hip joint and for preventing conflicts with surrounding structures. If the anteversion is too small, the front edge of the socket can irritate the iliopsoas tendon, especially during movements such as leg raises. A suboptimal implant position thus increases the likelihood of psoas impingement.

Causes of psoas impingement after hip replacement

Psoas impingement is usually caused by:

• Misposition of the acetabular cup : In particular, a reduced anteversion or an insufficiently deep position of the acetabular cup increases mechanical friction.
• Overhang of the pan rim : An overhang irritates the tendon.
• Muscle atrophy or weakness : A weakened iliopsoas often leads to dysfunctional stress that overstresses the tendon.
• Presence of foreign body reactions : Tissue reactions to the implant material can further promote pain.

Classic symptoms of psoas impingement

Patients with psoas impingement suffer from the following symptoms:

• Groin pain : This occurs particularly when raising the leg (flexion) and when sitting down. The pain can become chronic and worsen the longer the irritation persists.
• Strength limitations : Patients often report a feeling of weakness in the hip flexor muscle, which makes everyday movements difficult, such as climbing stairs or lifting the leg.
• Cracking sounds : Occasionally, those affected feel or hear a snapping sound as the tendon slides over the edge of the acetabulum.
• Limitations in everyday life : The pain can significantly impair the quality of life by limiting sporting activities or longer walking distances.

Diagnosis of psoas impingement

The following methods are used for a reliable diagnosis:

• Clinical examination : The doctor checks for typical symptoms such as groin pain during passive hip flexion and rotation.
• Diagnostic infiltration: The tendon is injected with a local anesthetic. If the symptoms disappear temporarily, psoas impingement is likely.
• Imaging procedures : X-rays and CT scans can reveal misalignments of the acetabular implant or mechanical conflicts.
• Ultrasound examination : May show inflammation or swelling of the tendon.
• MRI : Particularly helpful for visualizing soft tissues and inflammatory processes.

Treatment options for psoas impingement after total hip replacement

There are several approaches to treating psoas impingement:

Conservative therapy:

• Physiotherapy : Specific exercises to strengthen and mobilize the iliopsoas muscle can alleviate symptoms. Professional guidance is crucial to relieve strain on the muscle and avoid incorrect movements.
• Drug treatment : Anti-inflammatory drugs (e.g., NSAIDs) help to reduce swelling and pain.
• Injections : Corticosteroid injections into the iliopsoas tendon can provide short-term pain relief.

Surgical therapy:

• Hip socket replacement : In the case of a suboptimally positioned hip socket, surgical repositioning may be necessary to correct the anteversion.
• Tendon release : In severe cases, the iliopsoas tendon is surgically lengthened or relieved. However, this procedure should be carefully considered, as it can cause functional limitations.

Prevention of psoas impingement

• Optimal implant positioning : Precise planning of the acetabular cup and stem position can prevent complications. The correct anteversion position is particularly important in this regard.
• Rest and rehabilitation : After a hip replacement, a gradual increase in load is crucial to avoid overload and tendon irritation.
• Regular follow-up examinations : Follow-up examinations can detect and treat incipient psoas impingement at an early stage.

Conclusion

Psoas impingement is a frequently underestimated but serious complication following total hip replacement (THR). Early diagnosis and individually tailored therapy are crucial to reducing pain and functional limitations. Thanks to modern surgical techniques and improved implant technologies, many problems can be prevented in advance. The Endoprostheticum Mainz specializes in the optimal care and aftercare of hip replacement patients and offers comprehensive consultation and treatment options.