1 Anatomy and classification

Early surgical reconstruction with perfect restoration of the anatomical landmarks is the treatment of choice for displaced acetabular fractures. It achieves excellent and good long-term results in nearly 70% of cases [1, 2]. This is especially true if managed early by skilled surgeons familiar with Letournel’s classification and applying the surgical approach that best adapts to the fracture morphology [3–6]. The same assertion is not true for delayed fractures. Despite the spread of Letournel’s teaching through continuous education in trauma communities, and the evolution and access to adequate instruments and implants in developed countries, malreduction leading to malunion still occurs [1, 3, 5–9]. In countries where surgical treatment of the acetabular fracture is still mainly conservative, malunion and nonunion are more frequent. Complex trauma that necessitates prolonged intensive care unit resuscitation and care to save a life will delay acetabular reconstruction also leading to malunion or nonunion [3, 7]. According to Judet and Letournel, the timing of surgical care for acetabular fractures is divided into three periods: (1) from injury to 21 days (early); (2) 21 days to 120 days (delayed fractures); and (3) beyond 120 days (malunion and nonunion) [8]. In 1990 Letournel [8] reported 11 nonunion and 44 malunion treated after 120 days from the injury ( Table 2.22-1 ). Nonunions of the posterior wall fractures associated with a persistent dislocation were considered a separate entity because they had a greater chance of avascular necrosis [8]. Open reduction of the acetabular fractures after 21 days from injury may result in difficult surgery secondary to the rapid healing process of the innominate bone and remodeling of the fracture lines as well as the formation of scar tissue [5, 7, 8, 10]. Therefore a malunion or a nonunion of the initial fracture can occur when immature callus or fibrous tissues fills the fracture gaps and the fragments are retracted or fixed in a displaced position ( Fig 2.22-1 ) [5, 7, 8, 10].

Malunion and nonunion are rare conditions. A malunited elementary fracture may be relatively easy to solve; but in complex fractures, or when the fragments are multiple, like in T-shaped fracture with associated posterior wall or in both-column with an associated posterior wall fragment, the delay results in a much more complex situation and the primary surgical goal is to obtain secondary congruence [5, 7, 8, 11]. Complete acetabular nonunion is rare [8, 12–15], which is characterized by pain related to the movement. Nonunions are more easily treated because the fracture lines are more recognizable ( Fig 2.22-1 ) and only the soft-tissue attachments make the reduction difficult. The pathological anatomy of the malunion always depends on the initial fracture type; the healing process may lead to a malunion and remodeling of fracture lines and to a nonunion of some segments because of the important residual displacement of the fracture. After 4 months the fracture appears organized and remodeled, either the malunion or the nonunion condition may be expected to persist [8]. Not all malunions are symptomatic, like in some both-column fractures where all fragments remain separated but congruent to the femoral head achieving a secondary congruence [5, 7, 8, 11]. A different condition exists following surgical treatment when a true malunion without congruency or a nonunion condition may exist [1]. Because of the remodeling of iliac bone and the malunion or nonunion, reconstruction represents a major problem and usually osteotomies are performed to correct the articular incongruence and to restore the acetabulum sphericity. Letournel [8] performed the first correction of a transverse malunited acetabular fracture in 1963 through a Kocher-Langenbeck approach.

2 Patient selection/indication

Clear-cut indications for attempting reconstructive surgery after malunion or nonunion of the acetabulum were described by Letournel [8]. The elements to appreciate before attempting a malunion on nonunion reconstruction are the following:

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  Amount and site of wear on the femoral head

  
  
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  Degree of osteoarthritis

  
  
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  Presence of avascular necrosis

  
  
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  Loss of congruence of the femoral head with the acetabulum [5, 8, 11]

  
  
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  Less frequent may be displacements that cause a femoroacetabular impingement ( Fig 2.22-2 , Fig 2.22–3 ).

Also important is the patient’s age as extensile surgery may be contraindicated after 50–55 years. At this age the patient will more easily accept a total hip replacement (THR). We must also understand that this is a different pathology to a dysplastic hip. Acetabular trauma causes a sudden and acute disruption of a normal status and is associated with serious biological damage to joint cartilage; a dysplastic hip instead is an evolving condition. Generally, patients with an acetabular malunion complain of pain during activity, increasing in severity, a limp, decreased range of motion, and eventual necessity of walking aids [11]. This is due to the articular incongruence, where the contact area between the head and the acetabulum is reduced, increasing the articular pressure during weight bearing. Another reason is the wear of the femoral head, while articulating against a malreduced fracture. The result of these conditions is development of osteoarthritis [1, 5, 7–9]. The clinical presentation of nonunion is characterized by pain during weight bearing, pain when the hip is actively mobilized, and a limp; passive mobility of the hip joint may be significant, while painful in some range of motion areas.

The only way to prevent such an unfortunate series of events is to restore the normal congruency of the joint [1, 5, 7–9]. Before attempting repair the surgeon must distinguish between fracture treatment and treatment of posttraumatic hip degeneration. Older patients who have a complex fracture pattern and also femoral head damage may not be suitable for a reconstructive hip-preserving procedure but will need a THR. Nevertheless, in some instances it is necessary to reconstruct the acetabulum to allow a prosthetic replacement. The reconstruction of acetabular fractures after 120 days from the event is dictated by the fracture morphology, the degree of displacement, the number of fragments, the residual tectal and posterior wall impaction, the skill of the surgeon, and the resources of the healthcare system. Also the association of abdominal or urogenital injuries may delay or contraindicate the acetabular reconstruction [11]. Open wounds in the same extremity can increase the risk of infection. White blood cell count, erythrocyte sedimentation rate, and C-reactive protein level must be evaluated. Patients suffering from a long period of sickness and incapacity (resuscitation or intensive care unit) and who are younger than 40 years, living in a high-income country, and have an active lifestyle will be suitable candidates for reconstructive surgery. Patients older than 50 years tend not to accept the risk of this difficult surgery, which has a high risk of failure. The femoral head status is of great prognostic importance. Damage to the femoral head can be due to localized, central, or peripheral wear. It usually increases with time especially when associated with complex acetabular fractures leading to an osteoarthritic degenerative process. If wear of the femoral head is present in the cartilage or in the subchondral bone, reestablishing the parallelism or congruency of the joint space may be impossible [1, 5, 8, 11]. When the head is posteriorly or centrally dislocated the damage to the femoral head can be limited because contact between the head and the iliac bone is circumscribed to a nonweight-bearing area unless skeletal traction is applied ( Fig 2.22-4 ). Severe damage to the femoral head restricts the possibility of reconstruction. Hip arthrodesis can also be considered a solution in young patients who are involved in heavy labor in countries where governmental assistance is not always available. Hip arthrodesis restores the bone stock and can be easily converted to THR in the future. However, this possibility is not considered by most surgeons because of lack of information and because of the false belief that hip fusion results in a low quality of life. Conversely, THR has several advantages as a less invasive surgical technique and documented long-term efficacy especially with the new wear-resistant bearings. Furthermore, the excellent clinical results of THR are well known and more likely to be accepted but the patient must know that negative or catastrophic results can occur. In certain circumstances, like local infection, acetabular nonunion, excessive acetabular medialization, deformity, or lack of bone stock, an acetabular reconstruction is necessary to allow THR to be performed. A well-documented informed consent must also be obtained so that the patient and his/her family are aware of the serious complications and the potential for a less than ideal result.