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HIP

The hip joint

Osteoarthritis, avascular necrosis and dysplasia; primary hip replacement and revision of failed implants.

Most hip replacements are performed for osteoarthritis — the progressive loss of the cartilage covering the femoral head and the socket. It causes groin pain that can radiate to the thigh and knee, morning stiffness, and growing difficulty walking, putting on shoes and climbing stairs. It does not resolve on its own: conservative treatment controls symptoms, while replacement remains the definitive solution once pain limits daily life.

Other conditions I treat

  • Avascular necrosis of the femoral head — the death of bone tissue caused by interrupted blood supply, which can lead to collapse of the head and secondary arthritis. Early diagnosis by MRI matters, because in the initial stages there are options that may avoid replacement.
  • Developmental dysplasia of the hip — a socket too shallow to contain the femoral head properly, concentrating load on a reduced surface and causing early arthritis. In adults, replacement requires careful planning because the altered anatomy changes where the components must sit.
  • Periprosthetic fracture and implant failure — see revision surgery below.

The direct anterior approach

Surgical technique

The direct anterior approach reaches the hip by passing between muscles rather than cutting through them. It follows the Hueter interval, a genuine internervous plane: laterally the tensor fasciae latae, supplied by the superior gluteal nerve; medially the sartorius and rectus femoris, supplied by the femoral nerve. Between two different nerve territories there is always a natural boundary, and this approach uses it. No muscle is divided or detached — they are simply retracted apart.

The patient lies supine rather than on their side. That keeps the pelvis in a stable, neutral position, which makes it easier to control cup orientation and leg length, allows intraoperative fluoroscopy, and lets the two legs be compared directly.

Cross-section of the right hip showing the femoral nerve territory in green and the superior gluteal nerve territory in purple, with the direct anterior approach passing between them
Cross-section of the right hip. The green area is the territory of the femoral nerve, the purple area that of the superior gluteal nerve. The blue arrow follows the direct anterior approach: it runs exactly along the boundary between the two and reaches the joint without crossing any muscle belly.
Compared with the posterior approachFindingWhat it means
Pain in the first 72 hoursin favourConsistently lower pain scores over the first three days.
Function at 2–6 weeksin favourBetter functional scores in the early weeks — the most consistent advantage.
Length of stayin favourShorter hospital stay on average.
Function at 3 months and beyondno differenceAt three months, six months and one year the two groups are equivalent. The advantage is in the speed of recovery, not the final result.
Dislocation risknot demonstratedThe anatomical rationale is strong — the posterior structures are left intact — but meta-analyses of randomised trials have not confirmed a statistically significant reduction.
Operating timeagainstLonger on average, particularly during the learning curve.
Thigh numbnessagainstA complication specific to this approach, involving the lateral femoral cutaneous nerve. Purely sensory: it never affects strength or walking.

The approach is not right for everyone. Significant obesity, severe deformity, previous hip surgery, poor bone quality or the need for wide exposure all point towards a different route. The approach is a means to a result, not a goal in itself.

Femur First and revision

Further techniques

Femur First

A planning philosophy that reverses the usual order: the femoral component is positioned first, and the socket is then oriented to match it. Because the combined orientation of the two components determines how far the hip can move before impingement, starting from the femur — whose anatomy cannot be altered — allows the cup to be adapted to the individual rather than placed at a standard angle.

Revision hip replacement

Revision surgery replaces an implant, wholly or in part, once it has stopped working. The main causes are loosening of the components, wear of the bearing surfaces, recurrent dislocation, periprosthetic fracture and infection. It is more demanding than primary surgery: it needs dedicated planning, specific implants, and — in infection — a staged protocol.

Periprosthetic infection is the hardest scenario. Treatment usually involves two stages: removal of the implant with placement of an antibiotic-loaded spacer, a course of targeted antibiotic therapy, and reimplantation once the infection is controlled.

PL
Dott. Pierattilio Lupi
Consultant Orthopaedic Surgeon

Medical degree and specialist training in Orthopaedics and Traumatology (with honours) at the University of Parma. Head of the Orthopaedics and Traumatology Unit at Casa di Cura Figlie di San Camillo in Cremona, Italy. His practice covers hip, knee and shoulder replacement, revision surgery and personalised alignment in knee arthroplasty. Full profile →

Registered with the Medical Council of Cremona, no. 2707
Consultations in Italian and English
Written and reviewed by the author · Last updated: