Surgical techniques—acute total hip arthroplasty in nonreconstructible geriatric acetabular fractures

Why should you consider primary total hip arthroplasty?

Conventional surgical treatment for acetabular fractures in the form of open reduction and internal fixation (ORIF) can be associated with inferior clinical outcomes in the elderly population [1]. Age has been shown to be an independent risk factor for failure after ORIF of acetabular fractures [3]. Fracture patterns that do not allow anatomical reduction and fractures with major chondral damage, such as the ones with superior dome impaction and severe marginal impactions, are considered a high risk for failure after ORIF. Indeed, the reported failure rates after ORIF in the elderly population are as high as 64% with the need for conversion to hip arthroplasty occurring within 3 years [2].

With such poor short-term clinical outcomes after ORIF in this population, it is quite understandable that the indications for and practice of THA alone or with ORIF (combined hip procedure) as a primary treatment for acetabular fractures have seen a rapid increase over the last decade. A successful primary THA in the acute setting has the advantages of early mobilization and a reduced need for further surgical procedures. However, THA in the setting of an acute acetabular fracture is a complex procedure with higher levels of morbidity and complications than THA for arthritis or fractures of the femoral neck. The reported results on outcomes and complications have been variable in the recent literature [4, 5].

When to perform a primary total hip arthroplasty? Best indications considering risks and complications.

With anatomical reduction being possible only in about 50% of geriatric acetabular fractures [6], it is very important to consider THA with supplemental ORIF in a wide variety of injury patterns. Apart from poor acetabular injury characteristics, such as chondral impaction, comminution, and associated fractures in the femoral neck or head (Figure 1), important patient characteristics like osteoporosis, age, gender, and associated medical comorbidities should also be considered when choosing THA with ORIF or ORIF alone. Given that some of the more recent literature has reported a higher incidence of medical and surgical complications with acute THA and supplemental ORIF [7, 8], it is important to carefully weigh risks against benefits of this technically complex procedure. If THA can be performed through the same surgical approach used for ORIF, or by extending it, then it is less likely to be riskier than ORIF alone. ORIF of both columns through separate surgical approaches combined with THA in a single setting can be associated with increased morbidity but, if needed, can be staged to minimize risks.

Which surgical approach?

The choice of surgical approach for THA depends on the fracture pattern and the intended method of internal fixation. The posterior approach is the most used approach reported in the literature and is preferred for many reasons: 1) It provides access to the posterior column for plate fixation, which is considered more important for fracture stabilization and subsequent component stability. 2) It allows direct reconstruction of the fragmented and nonreconstructible posterior wall by auto-/allografts or metallic augments (Figure 2). 3) It provides access to the ilium and ischium, which is important for achieving secured points of fixation to anchor cementless acetabular components. 4) It provides access to the more proximal portions of the ilium and ischium, both of which are needed for implanting cages, cup-cage constructs, larger buttress augments, and custom triflange components, and finally 5) provides ease of access and trajectory for inferior “kickstand” screws into the pubis.

“In cases of isolated, comminuted posterior wall fractures,” comments Gavaskar, “our preference is to disregard the wall fragments if primary cup stability is not compromised and there is more than 70% host bone contact. In cases with bigger wall involvement which compromises the cup stability, reconstruction of the fragments with multiple spring plates under the main posterior column buttress plate can be considered, though this is a more difficult technique. Maintaining the reduced position of the comminuted wall fragments without the femoral head can be difficult and care has to be taken during acetabular reaming. Our preferred option for larger wall involvement is to neglect the wall fragments and reconstruct the wall with the femoral head autograft as a ‘Figure 7’ graft, or to use a trabecular metal augment in a flying buttress fashion.”

Fractures such as the anterior column fracture with or without a posterior hemitransverse component and the associated both-column fractures—more commonly seen in the elderly age group—need primary access from the anterior side. Gavaskar remarks: “Our preference is to approach these fractures through the AIP approach, if the medial quadrilateral plate needs buttressing to lateralize the femoral head.” Fixation is performed with contoured supra- and infrapectineal plates or the recently introduced anatomical buttress plates. Infraacetabular screw fixation through the AIP or the second window of the ilioinguinal approach and screws inserted from the supraacetabular corridor through a small lateral window can be used to secure indirect stabilization of the posterior column. In cases where the quadrilateral plate is not grossly displaced, the iliofemoral approach can provide easy and fast access to the anterior column with indirect reduction and fixation of the posterior column. The approach can also be extended distally into the Smith-Peterson interval to implant the prosthetic components.

Acetabular preparation and prosthetic options

Acetabular preparation is an important step and has to be carefully performed aiming for primary cup stability with optimum contact by wedging the acetabular component between the anterosuperior and posteroinferior quadrants of the acetabulum. Most often some underreaming is needed in these cases, depending on the bone quality and component used. It is also important to trial the cups. Primary cup stability—without significant and uncontrolled medialization—must be achieved. If primary cup stability cannot be achieved at trialing—due to an uncontained acetabulum—cages should be considered to avoid premature failures.

A multihole porous-coated socket is most commonly used. Previous studies have shown that uncemented sockets are better than cemented ones in terms of long-term survival [10, 11]. The ability to choose different liner and head options also helps the surgeon with modularity and flexibility. Highly porous trabecular metal (TM) cups may have an advantage with their ability to osseointegrate faster even with less host bone contact. The possibility of creating holes and placing screws at the desired location and cementing a liner independent of cup position makes the TM cup an attractive option in cases of limited host bone and stability. Contained defects after internal fixation can be impaction grafted, and rim or segmental defects can be reconstructed with TM augments. Using shaped auto-/allograft struts to reconstruct rim defects is an option, but factors such as poor host bone quality in very old patients, unreliable allograft healing, and possible delay in weight bearing, have to be considered.

Reinforcement rings or cages are an option when plate fixation of the columns does not restore sufficient stability to implant a hemispherical socket. The use of rings or cages help bridge the fracture and provide additional points of fixation into the ilium, ischium and pubis. They also act as an antiprotrusion device in case of large, uncontained medial wall defects, though this scenario has become less common after quadrilateral plate buttressing with plates. Since reinforcement rings or cages allow multiple fixation points on either side of the fracture, it is possible to use them without additional internal fixation or use minimal internal fixation like percutaneous column screws. The reinforcement rings or cages have been shown to achieve high initial stability compared to conventional plates and screws, but are associated with a lack of osseointegration in the long term [12]. The cup-cage construct [13, 14] is an attractive option to overcome osseointegration problems with conventional titanium cages. The TM shell used in the cup-cage construct achieves predictable osseointegration and the malleable cage helps achieve iliac and ischial fixation. The liner can be cemented into the cup-cage construct independently.

To minimize problems with instability, larger heads are preferred for articulation. In most cases, a 36- or 40-mm head may be sufficient to provide stable articulation free from instability and impingement. Dual mobility components are commonly favored in current practice since they allow the use of the largest possible prosthetic heads; the tremendous increase in range of movement due to the dual articulation may help overcome stability issues after THA in such cases.

Clinical outcomes after acute total hip arthroplasty

Patient outcomes and component survival

Acute management of acetabular fractures with primary THA is a complex and challenging procedure. Though advancements in ORIF techniques, implants, and prosthetic components have made it relatively safe, a high incidence of complications is still commonly reported.

Most published studies, including the recent ones on the topic, have a short follow-up ranging from 1–8 years [15]. The clinical outcomes reported have been variable, with some authors reporting satisfactory clinical outcomes while others report higher rates of complications, such as early acetabular component loosening, instability, and need for early revisions [16, 17]. Increasing age has been shown to be associated with less satisfactory clinical outcomes [18–20]. Mears [18] reported an average Harris Hip Score of 89 and the scores were less favorable in patients over 70 years. Other authors reported similar results as well [19, 20]. While most patients have been shown to regain independent walking ability, 25–30% of patients in the series by Yang et al [21] required assistive devices for ambulation. Various authors [22] have reported an acetabular component survival of 77–100%. Component survival is influenced by the acetabular fracture pattern, with elementary fractures doing better than complex associated fracture patterns. Herscovici et al [23] reported the lowest component survival of 77% at a mean of 29 months. In this series [23], most patients had an associated fracture pattern, which required simultaneous ORIF and THA using more than one surgical approach.

Revision rates after acute THA

Historically, the revision rate reported at short-term follow-up after primary THA ranges from 0% to 42% [24, 25]. The rates may be higher with long-term follow-up. The most common reasons for revision include instability, aseptic loosening, heterotopic ossification and infection. Heterotopic ossification is the most common complication reported ranging from 10% to 40%. More recently, Kelly et al [8] reported an overall revision rate of 18.2% and surgical complications in 27% of patients. Dislocation occurring in 15% of patients was the most reported complication and the incidence of infection was 10% in their series [8].

Outcomes in acute vs delayed total hip arthroplasty

Most previous literature [2, 26] has reported better outcomes with acute THA compared to delayed THA or ORIF for acetabular fractures in the elderly, citing early weight bearing, fewer revision surgeries, and possible surgical difficulties due to scarring in delayed THA as advantages. However, multiple recent studies [7, 8] have reported a higher rate of revisions and complications with acute compared to delayed THA. This may be attributed to the rapid expansion of the technique to include more complex fracture patterns needing dual surgical approaches and more complex reconstructions. It is also a reminder to be extremely cautious in choosing the right patients for this complex procedure. In a recently published contemporary series from the Mayo Clinic [27] on delayed THA for acetabular fractures, the authors reported 10-year component survival free from revision and reoperation to be, respectively, 98% and 97% [27].

Conclusion

Acute THA is a relevant surgical option that should be considered in selected acetabular fractures in the geriatric population. Though benefits such as early weight bearing and less need for revision procedures are encouraging, higher incidence of major medical and surgery-related complications in the postoperative setting raises concern. With a lack of high-quality comparative studies, currently, the surgeon has to carefully weigh risks and benefits in choosing acute THA in these patients. This is especially true in complex fracture patterns which may need more than one surgical approach to perform fracture fixation and THA.

So, when in doubt, it may be wiser to perform acute ORIF to heal the fracture and restore continuity across the columns, and then delayed THA if needed to minimize complications.