# Periprosthetic Fractures: Principles and Classification

## Overview

### Epidemiology

The incidence of periprosthetic fractures is rising in parallel with the growing number of arthroplasty procedures performed. Risk factors include osteoporosis, female sex, rheumatoid arthritis, revision surgery, osteolysis, cortical perforation from prior surgery, and stress risers from existing hardware. Periprosthetic femur fractures occur in 1-6% of total hip arthroplasties (higher in revision cases) and 0.3-2.5% of total knee arthroplasties. These injuries carry significant morbidity and mortality in elderly patients, with 1-year mortality rates of 10-15%.

### General Principles

The management of any periprosthetic fracture hinges on four key assessments: whether the implant is well-fixed or loose, the quality of remaining bone stock, the fracture location relative to the implant, and patient factors including age, activity level, and comorbidities. The overarching goal is stable fixation that permits early mobilization while maintaining or restoring implant function.

## Periprosthetic Fractures of the Femur (THA)

### Vancouver Classification

The Vancouver classification is the most widely used system for periprosthetic femur fractures around hip stems and directly guides treatment decisions.

| Vancouver Type | Location | Stem Status | Bone Stock | Treatment |
|---------------|----------|-------------|-----------|-----------|
| AG | Greater trochanter | Well-fixed | Adequate | Nonoperative if < 2 cm displacement; cerclage/plate if > 2 cm |
| AL | Lesser trochanter | May be loose | Adequate | Evaluate for loosening; nonoperative if stable |
| B1 | Around/below stem | Well-fixed | Adequate | ORIF (locking plate + cerclage cables) |
| B2 | Around/below stem | Loose | Adequate | Revision arthroplasty with long stem |
| B3 | Around/below stem | Loose | Poor | Revision with megaprosthesis/proximal femoral replacement |
| C | Below stem tip | Well-fixed | Adequate | Standard fracture fixation (plate or retrograde nail) |

#### Type A: Trochanteric Region

Type AG (greater trochanter) fractures are usually managed nonoperatively if minimally displaced. Operative fixation with cerclage wires or a trochanteric grip plate is indicated if displacement exceeds 2 cm with associated abductor dysfunction. Type AL (lesser trochanter) fractures may indicate underlying prosthetic loosening and should be evaluated with CT. Isolated stable fractures are managed nonoperatively, but a loose stem requires revision.

#### Type B: Around or Just Below the Stem

Type B1 fractures occur around a well-fixed stem with adequate bone stock. Treatment is ORIF using a locking plate combined with cerclage cables or wires. The plate must be long enough to span 2-3 cortical diameters past both the fracture and the stem tip. Type B2 fractures occur around a loose stem with adequate bone stock. Treatment is revision arthroplasty with a long-stem prosthesis that bypasses the fracture by 2 cortical diameters, often supplemented with cerclage cables and strut allograft. Type B3 fractures represent the most challenging scenario: a loose stem with poor bone stock. Treatment options include revision with a tumor or megaprosthesis, impaction grafting with a long cemented stem, or proximal femoral replacement. Structural allograft augmentation (allograft-prosthetic composite) may be considered.

#### Type C: Below the Stem Tip

Type C fractures occur below the prosthetic stem and are not directly influenced by the implant. They are treated as standard distal femur fractures with ORIF using a laterally applied locking plate or retrograde IM nail (if intercondylar space permits). The plate must extend proximally to overlap with the stem tip by 2-3 cortical diameters to manage the stress riser at the plate-stem junction.

### Assessment of Stem Stability

Radiographic signs of loosening include progressive radiolucent lines wider than 2 mm, subsidence, pedestal formation, and cement mantle fracture. Intraoperative assessment involves attempting to axially load and rotate the stem, where any motion indicates loosening. CT may help but is limited by metal artifact. When stem stability is uncertain, intraoperative exploration and direct assessment are warranted.

## Periprosthetic Fractures of the Femur (TKA)

### Lewis and Rorabeck Classification (Supracondylar)

Type I fractures are nondisplaced with an intact prosthesis and are managed nonoperatively with a hinged brace or long leg cast. Type II fractures are displaced with an intact prosthesis, requiring ORIF with a locking plate or retrograde IM nail. Type III fractures have a loose or failing prosthesis (displaced or nondisplaced) and require revision TKA with a long-stem distal femoral component.

### Su Classification (Supracondylar)

The Su classification is based on fracture location relative to the femoral component: Type I is proximal to the component, Type II originates at the proximal edge, and Type III is distal to the femoral component flange.

### Fixation Options (Type II -- Displaced, Prosthesis Intact)

Retrograde IM nailing requires an open-box femoral component or sufficient intercondylar space; posterior-stabilized designs may not accommodate a nail, and compatibility must be verified preoperatively. This approach offers load-sharing and biomechanically favorable alignment. A laterally applied locking plate (LISS or periarticular locking plate) is the standard approach when nailing is not feasible, with supplemental medial plating or cerclage cables considered in osteoporotic bone. Dual plating (medial and lateral) addresses severely comminuted or osteoporotic fractures. Cable-plate constructs provide adjunctive fixation around the prosthesis.

## Periprosthetic Fractures of the Tibia (TKA)

### Felix Classification

The Felix classification identifies four types: Type I is a tibial plateau fracture around the tibial tray, Type II is adjacent to the tibial stem, Type III is distal to the stem, and Type IV is a tibial tubercle fracture. Each is subclassified as A (well-fixed component), B (loose component), or C (intraoperative fracture). Well-fixed components are treated with ORIF; loose components require revision with a stemmed tibial component.

## Periprosthetic Fractures of the Humerus (Shoulder Arthroplasty)

### Wright and Cofield Classification

This classification parallels the Vancouver system for hip periprosthetic fractures, categorizing fractures by location relative to the stem tip. A well-fixed stem is treated with ORIF using plate and cerclage. A loose stem requires revision with a long-stem component. The incidence of these fractures is increasing with the growing use of reverse total shoulder arthroplasty.

## Periprosthetic Fractures Around the Elbow

### Mayo Classification

The Mayo classification is based on location (relative to the humeral or ulnar component tip), displacement, and component fixation status. Well-fixed implants with minimal displacement are managed nonoperatively. Displaced fractures or those with loose components require ORIF or revision.

## Fixation Constructs and Techniques

### Plate-Cerclage Constructs

A locking plate is applied to the bone adjacent to the prosthesis, with cerclage wires or cables passed around the bone and through or around the plate to secure fixation. This construct is critical near implants where screw purchase is limited to unicortical screws. Cable-ready plates have holes specifically designed for cerclage passage.

### Strut Allografts

Cortical allograft struts applied to the bone surface opposite the plate provide additional fixation points and augment bone stock. They are secured with cerclage wires and are particularly useful in B2 and B3 fractures during revision arthroplasty.

### Locking Plate Principles

Fixed-angle locking screws resist toggle in osteoporotic bone. Long plates spanning both the fracture and the stem tip or implant are essential. Unicortical locking screws are used where the implant prevents bicortical purchase. Screw density in the fracture zone is minimized per bridge plating principles.

### Intraoperative Fractures

Periprosthetic fractures recognized intraoperatively during arthroplasty often occur during component insertion, dislocation maneuvers, or cement removal. Treatment includes cerclage wires, use of a longer stem, or a change in fixation strategy. Prevention requires careful preparation, appropriate component sizing, and awareness of risk factors (stiff joints, revision surgery, osteoporosis).

## Postoperative Management

Protected weight-bearing (toe-touch) is maintained for 6-12 weeks depending on fixation stability. DVT prophylaxis is essential. Serial radiographs monitor fracture healing and implant stability. Bone health optimization including calcium, vitamin D, and anti-resorptive therapy is an integral part of treatment. Given the high morbidity in elderly patients, early mobilization and geriatric co-management reduce complications and mortality.

<image>A comprehensive diagram of the Vancouver classification of periprosthetic femur fractures after total hip arthroplasty. Show an anteroposterior view of a femur with a hip stem in situ. Illustrate each type: A (AG and AL — trochanteric region), B1 (fracture around a well-fixed stem), B2 (fracture around a loose stem), B3 (fracture around a loose stem with poor bone stock), and C (fracture below the stem tip). For each type, include a small icon showing the recommended treatment: cerclage for AG, plate-cable for B1, revision long stem for B2, proximal femoral replacement for B3, and standard plate fixation for C.</image>

<image>An illustration of a plate-cerclage fixation construct for a Vancouver B1 periprosthetic femur fracture. Show a lateral view of the femur with a well-fixed hip stem and a spiral fracture pattern around the stem. Apply a long locking plate laterally spanning from above the fracture to below the stem tip. Show cerclage cables passed around the bone and through the plate securing the construct at the level of the fracture and stem. Label the locking screws (bicortical distally, unicortical near the stem), cerclage cables, and the requirement for the plate to extend 2-3 cortical diameters past the stem tip.</image>

<image>A decision algorithm for management of periprosthetic fractures around TKA. Start with fracture identification, then assess: (1) prosthesis stability — well-fixed vs. loose, (2) fracture displacement — nondisplaced vs. displaced. Branch into: nondisplaced with well-fixed component (hinged brace, protected weight-bearing), displaced with well-fixed component (retrograde nail vs. locking plate vs. dual plating), displaced or nondisplaced with loose component (revision TKA with long-stem component). Include illustrations of each fixation option.</image>

## Clinical Pearls

The most important question in periprosthetic fracture management is whether the implant is well-fixed or loose, as this determines whether ORIF or revision is appropriate. Vancouver B2 fractures require revision arthroplasty because fixing bone around a loose stem leads to failure. Plates must extend 2-3 cortical diameters beyond the stem tip to prevent stress riser fractures at the plate end. Retrograde nailing for supracondylar periprosthetic femur fractures after TKA requires an open-box or compatible femoral component, which must be verified preoperatively. Intraoperative periprosthetic fractures are common during revision surgery, and cerclage wires and cables should always be available. Osteoporosis is the underlying problem in most periprosthetic fractures, and bone health must be addressed as part of the comprehensive treatment plan. Elderly patients with periprosthetic fractures have significant morbidity and mortality, making early mobilization and geriatric co-management critical. When stem stability is uncertain radiographically, surgical exploration with direct intraoperative testing is warranted.

## References

- Duncan CP, Masri BA. Fractures of the femur after hip replacement. *Instr Course Lect*. 1995;44:293-304.
- Lindahl H, et al. Periprosthetic femoral fractures: classification and demographics of 1049 fractures. *J Arthroplasty*. 2006;21(2):218-223.
- Rorabeck CH, Taylor JW. Periprosthetic fractures of the femur complicating total knee arthroplasty. *Orthop Clin North Am*. 1999;30(2):265-277.
- Moreta J, et al. Vancouver type B2 and B3 periprosthetic femoral fractures: a systematic review. *Hip Int*. 2020;30(1_suppl):34-42.
- Capone A, et al. Periprosthetic fractures: epidemiology and current treatment. *Clin Cases Miner Bone Metab*. 2017;14(2):189-196.