Periprosthetic fractures of the proximal femur: beyond the Vancouver classification

Key points

• Most periprosthetic femoral fractures are treated surgically: stem revision, revision combined with open reduction and internal fixation (ORIF), or ORIF alone.
• The key decision is whether the stem is loose, but loose stems are not always identified; Swedish registry data showed that up to 47% of stems in periprosthetic fracture were 'unknown loose'.
• The authors propose an algorithm based on patient history, stem design and plain radiographs to identify loose stems.
• Pain or reduced mobility before the fracture, comminution, stem subsidence, major osteolysis and a fracture at the level of primary fixation all point to a loose stem.
• Around cemented stems, a composite beam stem should be revised, while a polished taper stem can be considered well fixed if the cement/bone interface is intact.

Overview

This EFORT Open Reviews article addresses periprosthetic fractures of the proximal femur after total hip replacement (THR) and the difficulty of telling a well-fixed stem from a loose one. The Vancouver classification guides treatment, but loose stems are not always recognised, which results in unsatisfactory treatment. The authors combine concepts from Ninan et al and Baba et al with their own into a radiograph-based algorithm intended to identify loose stems more reliably.

Why the Vancouver classification is not enough

Periprosthetic femoral fractures have an expected incidence of 0.1–18% after THR, are reported as the third leading cause of revision in the first two years after surgery and the second in the long run, and have increased up to 2.5-fold over the past two decades. The Vancouver system classifies fractures by location (type A in the trochanteric region, type B around or just below the stem, type C well below the stem tip) and divides type B into B1 (well-fixed stem), B2 (loose stem, good proximal bone) and B3 (poor quality or severely comminuted proximal bone). B1 fractures are generally treated with ORIF and B2 fractures revised, yet several authors report higher failure rates of osteosynthesis around stems considered well fixed, suggesting that loose stems are being missed.

First steps: history and comminution

Two findings signal a high likelihood of a loose stem: increasing thigh pain on weight bearing or reduced mobility due to hip problems before the fracture, and a comminuted fracture. If neither is present, the pathway splits according to whether the stem was cemented.

Non-cemented stems

A fracture occurring intraoperatively or in the first few weeks after implantation indicates a loose stem, because the stem has not had the chance to integrate. Any subsidence on sequential radiographs means the stem should be assumed loose and revised, and major osteolysis also requires revision; where no earlier radiographs exist, CT with a metal artefact reduction algorithm can help. A fracture at the level of primary fixation of the specific design (metaphyseal for proximally fixed straight stems, diaphyseal for tapered stems, the proximal area for modular stems, the metaphyseal area and distal curve for anatomic stems) means the stem is loose, whereas fully coated stems may remain well fixed if only the metaphyseal or only the diaphyseal area is affected. Otherwise, intraoperative testing is the last step.

Cemented stems

A fracture around a composite beam (shape-closed) stem should be considered loose and revised. A polished taper (force-closed) stem is considered loose if the cement mantle is broken or deficient and interferes with the cement/bone interface, and can be considered well fixed if that interface is intact.

Frequently asked questions

Does the algorithm decide the final treatment?

No. It identifies loose stems, but patient factors such as age and health must also be weighed; with a one-year mortality of 30% after periprosthetic femoral fracture, conservative treatment should be considered in non-ambulatory patients and those with severe morbidity or low life expectancy.

Why should both trauma and arthroplasty expertise be available?

Because a loose stem may be identified only during surgery, the authors suggest that trauma and arthroplasty surgeons, or one surgeon with expertise in both, be present or on stand-by.

Has the algorithm been validated?

Not yet; the authors state that further studies on a larger scale are needed to validate it.

Source

Stoffel K, Horn T, Zagra L, Mueller M, Perka C, Eckardt H. Periprosthetic fractures of the proximal femur: beyond the Vancouver classification. EFORT Open Reviews 2020;5(7):449-456. DOI: 10.1302/2058-5241.5.190086. Open access under the CC BY-NC 4.0 licence. This page is a summary prepared by Medpresso from the original publication and is not a substitute for the full text or for medical advice.