While THA is still effective, clinical indications suggest that hip resurfacing may be a more suitable option for younger, active patients who want to run, play tennis, return to heavy work and an active lifestyle.

This need for a more durable, bone-preserving option drove the development of Hip Resurfacing Arthroplasty (HRA).

Unlike a total replacement, resurfacing preserves the femoral head. It simply caps it with a smooth metal covering, much like capping a tooth. But the journey to modern resurfacing wasn’t a straight line. It is a story of ambitious engineering, hard-learned lessons, and rigorous scientific refinement.

A History of Mechanistic Learning

The concept of hip resurfacing isn’t new. Early attempts date back to the 1930s with Smith-Petersen mould hemiarthroplasty¹. However, these early designs often failed. The materials available at the time - Teflon and early plastics - couldn’t withstand the immense forces placed on the hip joint.

By the 1970s, surgeons tried combining metal heads with polyethylene (plastic) cups, but these also faced challenges. The thin plastic shells required for resurfacing wore out quickly, leading to osteolysis (bone loss) and loosening of the implant¹. 

The Metal-on-Metal Breakthrough

The real turning point arrived in the 1990s with the reintroduction of metal-on-metal (MoM) bearings. Engineers realised that highly polished cobalt-chromium alloy could offer the durability that plastic lacked.

This era gave birth to the Birmingham Hip Resurfacing (BHR) system. Designed by Derek McMinn, the BHR demonstrated that resurfacing could work well. It used a specific metallurgy and geometry that maintained a fluid film of lubrication between the ball and socket, significantly reducing wear. 

Lessons from Reported Causes of Failure

The literature on hip resurfacing identifies several key factors that have historically contributed to early implant failure.

Common issues include technical aspects such as suboptimal surgical technique, especially incorrect component positioning or inclination, as well as patient-related variables like small femoral head size, poor bone quality, and underlying conditions such as hip dysplasia or inflammatory arthritis.

Metal sensitivity and adverse local tissue reactions are also recognised causes of earlier complications in certain patients. Large registry studies have repeatedly shown that the best outcomes occur when strict selection criteria are followed - specifically, resurfacing in younger male patients with adequate femoral head size and good bone stock, performed by experienced surgeons using precise technique. These insights have shaped current clinical indications and refined surgical protocols, supporting safer and more durable outcomes in modern practice'. 

The Paradigm Shift: Defining the 'Ideal Candidate'

Today, we know that the device is only half the equation. The other half is the patient. The extensive data from national joint registries in the UK and Australia has allowed surgeons to pinpoint exactly who benefits most from hip resurfacing.

It is no longer a "try it and see" procedure. We now have a strict profile for the "ideal candidate."

Understanding Contraindications

Just as important as knowing who could have the surgery is knowing who could not. Surgeons generally avoid HRA for patients with:

• Gender and Age: Registry data shows that males under 55 years of age achieve the best outcomes. In this group, implant survivorship is exceptional, often exceeding that of standard total hip replacement. 

• Femoral Head Size: Size matters in resurfacing. Larger femoral heads (greater than 50mm) offer better mechanics and lower wear rates. Patients with head sizes smaller than 44mm face a significantly higher risk of revision (around 13.8%)

• Bone Quality: Because the femoral head is preserved, the bone inside it must be healthy. Patients with cysts or necrotic (dead) bone are generally not suitable, as the bone may collapse under the implant. 

Understanding Contraindications 

Just as important as knowing who could have the surgery is knowing who could not. Surgeons generally avoid HRA for patients with: 

• Hip Dysplasia (DDH): Patients with shallow or malformed hip sockets often have poor outcomes with resurfacing, with survival rates dropping to around 78% at 20 years . 

• Inflammatory Arthritis: Conditions like rheumatoid arthritis can weaken the bone, making the femoral neck fragile and prone to fracture. 

• Metal Sensitivity: Since current resurfacing devices use metal-on-metal bearings, patients with known metal allergies are typically excluded to prevent adverse tissue reactions. 

• Female Gender (Historical Context): Historically, women have had higher failure rates with MoM resurfacing (approx. 81.3% survivorship at 21 years vs 92.5% for men). This is largely attributed to smaller average bone size and higher rates of undetected dysplasia, though new ceramic technologies may soon change this outlook. 

The Future is Precise

The evolution of hip resurfacing has moved from a phase of experimentation to one of precision. We have moved past the "design failures" of some Metal-on-Metal devices and honed in on what can work: the BHR design used in young, active males with large bones.

By adhering to strict patient selection criteria and following a precise surgical technique, surgeons can now offer a procedure that preserves bone, restores natural biomechanics, and allows patients to return to high-impact sports without the restrictions of a standard hip replacement.'