Short answer

Why the current plan is failing

• The modalities only give temporary relief. IFT and ultrasound have little lasting effect on their own. Your pattern fits this: improvement for about 20 days, then a return to baseline within 5 days of stopping.
• Extension exercises may not suit this patient. The MRI shows disc protrusions, and the patient has a left hip problem. Extension helps only if he has a directional preference for extension. If it is not helping, or is irritating the hip or facets, stop it.
• The MRI is mild and may not explain all the symptoms. The L4-5 protrusion touches the left traversing (L5) root. L5-S1 has no neural compression. Modic type II change at the L5 inferior endplate suggests chronic discogenic pain. These findings are common in people without symptoms, so they need to match your clinical exam.
• The hip is a likely contributor. AVN of the hip often presents as groin, buttock or referred knee pain (Comprehensive Clinical Nephrology, 7th Edition, Avascular Necrosis). Hip pain can also be referred from the lumbar spine, and the reverse is true (Textbook of Family Medicine 9e, Key Points). An AVN that is progressing toward collapse can cause pain that keeps returning and does not respond to physiotherapy.

Step 1: Re-assess in the next session

• Where is the pain, and is it worse on weight-bearing or after first steps?
• Look for groin pain, pain with FADIR and FABER, and painful or limited hip internal rotation and flexion.
• Check for a Trendelenburg sign and gait pattern.
• Check leg length discrepancy and pelvic obliquity. This is common after a THR and strains the lumbar spine and the left hip.

• Test for a directional preference (repeated flexion and extension, McKenzie style).
• Do SLR and slump tests.
• Check L4 to S1 myotomes, dermatomes and reflexes.
• Do the SIJ provocation cluster. SIJ pain is common after THR and with asymmetric loading.

• Ask about night pain, weight loss, fever, bladder or bowel change, and saddle numbness.
• Ask about steroid use or alcohol (AVN risk factors), and why the right hip needed a THR.
• Screen fear-avoidance, sleep and mood.
• Record baselines: NPRS, Oswestry (ODI), PSFS, a hip score such as HOOS, and walking tolerance.

Step 2: What to start

• Explain that the MRI findings are common and that hurt does not always mean harm.
• Give pacing advice, avoid prolonged sitting, and have him change position every 30 minutes.
• Aim to get him off painkiller dependence by building his tolerance step by step.

• If extension reduces leg or back pain and centralizes it, keep it.
• If flexion or neutral positions feel better, use that direction.
• Add trunk stabilization: McGill big 3 (modified curl-up, side bridge, bird-dog), then dead bug and glute bridge.
• Teach hip-hinge training and lifting mechanics.
• If L5 radicular signs are present, add gentle neural sliders (not tensioners).

• Strengthen the hip abductors and gluteus maximus on both sides. Start with side-lying or bridging, then standing and band work.
• On the right THR side, follow any precautions from the surgeon. Strengthen the abductors and train gait.
• On the left AVN hip, use pain-free strengthening and range of motion.
• Avoid deep squats, impact, jumping, forced end-range rotation, and prolonged single-leg loading.
• Consider a cane in the right hand to unload the left hip, and check footwear or a shoe lift if there is a leg length difference.

• Start low-impact aerobic work: hydrotherapy or pool walking, cycling, or progressive walking.
• Most trials show exercise is more effective than passive care for long-term relief. Recent reviews support this: systematic review 2025 and the Cochrane review on acute low back pain.

• Use these only as a short-term aid: gentle lumbar and hip mobilization, soft tissue work, or TENS and heat before exercise.
• Do not rely on them as the main treatment.

Step 3: When to refer

• Orthopaedics, now: he should have a repeat hip X-ray or MRI of the left hip. Grade 2 AVN can progress to collapse, and the left hip may be the main pain source. Ask the surgeon about weight-bearing advice and treatment options.
• Pain physician or spine specialist: if pain is unresponsive after 6 weeks of properly targeted exercise, if radicular pain is disabling, or if he is still on regular painkillers. A targeted epidural or root block may help, and it can also show you whether the L5 root is the source.
• Urgent: any progressive weakness, foot drop, bladder or bowel change, saddle anaesthesia, or fever with severe night pain.
• Medical review: if bone health, vitamin D, or steroid or alcohol use are concerns for the AVN.

Suggested timeline