Hip Replacement: Understanding Pain in Your Unoperated Hip

Why does my good hip hurt after hip replacement?

Pain in the unoperated hip after a total hip replacement (THR) is a surprisingly common experience, often stemming from the body's complex biomechanical adjustments, altered gait patterns, and compensatory movements made during recovery and adaptation to the new joint.

Understanding the Body's Compensation Mechanisms

Following a hip replacement, your body undergoes a significant period of adaptation. While the surgical hip is healing and regaining function, the "good" or contralateral hip often takes on an increased load and experiences changes in its biomechanical environment. This is a natural, albeit sometimes painful, response to maintain mobility and stability.

Biomechanical Shifts and Increased Load

The most significant reason for pain in the unoperated hip often relates to altered weight-bearing and movement patterns:

• Altered Gait Mechanics: Post-surgery, individuals frequently adopt a protective gait, favoring the operated leg or altering their stride to reduce discomfort. This can lead to an uneven distribution of weight, placing excessive stress on the "good" hip during walking, standing, and other daily activities.
• Increased Load Bearing: The unoperated hip may bear a disproportionately higher percentage of your body weight and impact forces. This increased, repetitive strain can irritate the joint capsule, cartilage, tendons, and bursae around the good hip.
• Pelvic Tilting and Rotation: To compensate for stiffness, weakness, or pain in the operated hip, the pelvis may tilt or rotate. This compensatory movement places abnormal stresses on the sacroiliac (SI) joint, the lumbar spine, and the unoperated hip joint itself.
• Spinal Alignment Changes: The kinetic chain is interconnected. Changes in hip and pelvic alignment can propagate up the spine, leading to compensatory curves or rotations in the lumbar region, which can, in turn, refer pain to the hip or buttock.

Muscular Imbalances and Overuse

Muscles surrounding both hips and the core play a critical role in stability and movement. Post-surgery, these can become imbalanced:

• Weakness on the Operated Side: The muscles surrounding the surgically repaired hip, particularly the gluteal muscles (gluteus medius, minimus, maximus), are often weakened due to surgery-related trauma, disuse, or nerve inhibition.
• Overuse of Contralateral Muscles: To compensate for this weakness, the gluteal muscles and other hip stabilizers on the unoperated side must work harder and more frequently. This chronic overuse can lead to muscle fatigue, strain, trigger points, and tendinopathy (e.g., gluteal tendinopathy, trochanteric bursitis) around the "good" hip.
• Core Instability: A weakened core can exacerbate pelvic instability, forcing hip muscles to work harder to stabilize the trunk, further contributing to overuse and pain.

Pre-existing Conditions and Referred Pain

Sometimes, the pain isn't entirely new but rather an exacerbation of an underlying issue or referred from another source:

• Contralateral Hip Arthritis: The "good" hip may already have early or moderate degenerative changes (osteoarthritis) that were overshadowed by the severe pain of the hip that underwent replacement. The increased load and altered mechanics simply accelerate the symptomatic progression of this pre-existing condition.
• Lumbar Spine Issues: Low back pain, disc herniations, spinal stenosis, or facet joint arthritis can refer pain to the hip and buttock region. Altered posture and gait post-THR can aggravate these spinal conditions.
• Sacroiliac Joint Dysfunction: Increased stress on the SI joint due to pelvic asymmetry or altered gait can lead to localized pain that may radiate to the hip.
• Bursitis or Tendinopathy: Inflammation of the bursae (fluid-filled sacs that cushion joints) or tendons around the "good" hip (e.g., greater trochanteric bursitis, iliopsoas tendinopathy) can arise from increased friction and overuse.

Rehabilitation and Management Strategies

Addressing pain in the unoperated hip requires a comprehensive approach, often involving your surgical team, physical therapist, and a commitment to your rehabilitation:

• Targeted Physical Therapy: A skilled physical therapist can assess your gait, muscle strength, and flexibility on both sides. They will design exercises to:
  • Restore Symmetrical Gait: Re-educate your body to walk with an even stride and weight distribution.
  • Strengthen Core and Gluteal Muscles: Crucial for pelvic stability and reducing the burden on hip joints.
  • Improve Flexibility and Range of Motion: Address any stiffness or tightness in hip flexors, extensors, and rotators.
  • Address Specific Imbalances: Correcting muscle weaknesses or overactivity on either side.
• Pain Management: Over-the-counter anti-inflammatory medications (NSAIDs), ice, or heat can help manage acute pain and inflammation. Always consult your doctor before starting new medications.
• Activity Modification: Temporarily reducing activities that exacerbate pain can provide relief and allow tissues to heal. Gradually reintroduce activities as tolerance improves.
• Footwear Assessment: Appropriate, supportive footwear can significantly impact gait mechanics and joint loading.
• Ergonomic Adjustments: Ensuring proper posture and body mechanics during daily tasks can prevent undue stress.

When to Seek Medical Advice

While some discomfort is normal during the post-operative period, certain symptoms warrant immediate medical attention:

• Persistent or Worsening Pain: If the pain in your "good" hip does not improve with rest or rehabilitation, or if it intensifies.
• Sharp, Sudden Pain: Especially if it's accompanied by a sensation of instability or a "giving way."
• New or Worsening Numbness or Weakness: In the leg or foot.
• Signs of Infection: Redness, warmth, swelling, or fever.
• Inability to Bear Weight: If you suddenly cannot put weight on the unoperated leg.

In conclusion, pain in the unoperated hip after a total hip replacement is a common and often understandable consequence of the body's adaptive processes. By understanding the underlying biomechanical, muscular, and neurological factors, and by diligently engaging in a targeted rehabilitation program, most individuals can effectively manage and resolve this discomfort, ensuring a more balanced and comfortable recovery.