Case guide

An overview of the cases and how we classify them.

Understanding our case studies

We’ve chosen cases that represent the range of solutions available during first-time (primary) and repeat (revision) hip replacement. All cases focus either on the pelvis (acetabular) or thigh bone (femoral).

We’ve also added categories of complexity and, for revision cases, we’ve indicated how the National Joint Registry records the reason for revision in each case. Cases are also labelled according to the underlying diagnosis (such as hip dysplasia, infection) and also interesting and topical features (such as use of 3D printed implants or 3D printed guides).

The icons we use

Assessing surgical complexity

We’ve taken a practical approach to assessing the complexity of hip ops. With our ladders of reconstruction we focus on the level of surgical work required. This avoids the complications of incorporating other technical and diagnostic factors.

While there’s is no universally accepted definition of complexity of hip problems, there are classification systems for the severity of certain disease types. For example, relevant to primary hip replacement, there are classifications of severity osteonecrosis (avascular necrosis), hip dysplasia, proximal femoral version (spiralling of the thigh bone), and proximal femoral tapering. And relevant to revision hip replacement there are classifications of bone defects of the acetabulum, bone loss of the femur, and type of periprosthetic fracture. 

However, it is more straightforward to explain the complexity according to the treatment used to solve the problem, as this is how the surgeon needs to approach the problem and how the patient can best understand the problem. This is why we use the ladder of reconstruction to describe complexity according to the treatment category used and ignore the many variables involved in a diagnostic or mechanistic descriptive classification, which make the subject difficult to teach surgeons and difficult for patients to understand.

We use a ladder sequence to help surgeons make sense of the choices faced in carrying out acetabular reconstruction. As you move up the levels or ‘rungs’ of the ladder the size of patient defect, level of surgical exposure and complexity of implant all increase. 

We encourage surgeons to do the detective work first, then identify the appropriate rung of the ladder and plan a solution based on this, always seeking out the minimum level of intervention that will achieve the right outcome. A general principle is to opt for the lowest rung on this ladder, saving higher rungs for later if needed. You’ll find the cases in this chapter organised according to this ladder.

Acetabular reconstruction

THE ACETABULAR LADDER OF RECONSTRUCTION

  • Custom Tri-flange cup acetabulum

  • Anti-protrusion cage and cup

  • Augmented highly porous cup

  • Jumbo-sized highly porous cup

  • Bone graft with highly porous cup

  • Exchange cup for highly porous cup

  • Bearing exchange

  • No action taken

Femoral reconstruction

For our femoral reconstruction courses we use a ladder concept similar to that for acetabular reconstruction, to help surgeons make sense of the choices. Again, as you move up the levels or ‘rungs’ of the ladder, the size of patient defect, level of surgical exposure and complexity of implant all increase. In this way, the principle of bone conservation defines the hierarchy of options available in our ladder of reconstruction of the femur.

THE FEMORAL LADDER OF RECONSTRUCTION

  • Proximal femoral replacement

  • Modular taper fluted stems

  • Long stems

  • Primary components

  • Conservative management

Reasons for hip revision

As with any mechanical device, a hip implant can fail for a number of reasons.

Common reasons for revision surgery include mechanical failure, infection and dislocation. The National Joint Registry provides the most widely used scheme for classifying the reasons for revision surgery.

National Joint Registry

The National Joint Registry (NJR) is a comprehensive database that collects information on joint replacement surgeries across the UK. The NJR uses a standard coding system to categorise the reasons for hip revision surgery. These codes allow for consistent documentation and analysis of the causes behind hip replacements requiring revision. Below are some of the common hip revision reason codes used by the NJR, and below is a summary of the main reasons, with relevant examples from our cases.

THE NJR REASON CODES

  • This code is assigned when the hip replacement components become loose due to a breakdown of the bond between the implant and the bone.

  • This code is used when an infection occurs in the hip joint, either immediately after the replacement surgery or later on.

  • When a fracture is observed around the implanted components of a hip replacement, this code is assigned.

  • This code is used when the ball and socket components of the hip replacement become separated, resulting in hip dislocation.

  • If a patient undergoes hip revision surgery primarily due to persistent pain or discomfort, this code is assigned.

  • When the hip replacement becomes unstable, leading to issues with mobility and functionality, this code is used.

  • This code is assigned when significant wear and tear of the artificial joint surfaces occur, necessitating revision surgery.

  • In cases where the reason for hip revision surgery does not fit into any of the above codes, the NJR assigns the "Other reasons" code.