Acetabular and Pelvic Fractures1

To accept the concept that any degree of residual incongruity inevitably results in late arthritic changes is wrong. It cannot be true. Thousands, if not millions, of people who sustained acetabular and other fractures in the past and did not have anatomical repositioning of the fragments never developed arthritic changes, and among those who developed them, many never became sufficiently symptomatic to require surgery. This statement is made not to suggest that congruity of articular cartilage fractures is not desirable, but to emphasize that other factors must be included in the decision-making process. Furthermore, many patients whose incongruity was corrected by surgical means are not exempt from late degenerative changes. The surgery necessary to obtain surgical stabilization is not infrequently accompanied with secondary complications such as heterotopic bone, chondrolysis, nerve injury, infection, and even death. Furthermore, surgical treatment does not guarantee a perfect anatomical reduction. In addition, the mortality from pelvic fractures, particularly in the elderly, is high. The surgery to stabilize these fractures is usually very traumatic and debilitating.

The effect of incongruity on articular cartilage is a subject which we are just now beginning to understand. Nature spontaneously repairs small step-off defects without leading to arthritic changes. The works of Lansinger, in Sweden, Kristensen, in Denmark, Dietz and Marsh, in Iowa, and our own by Llinas, and Lovasz are convincing, even though they do not deal with the hip but with the knee and/or ankle joints. Some of these investigators have demonstrated in long-term follow-up studies that most fractures of the tibial condyles that healed with residual significant incongruity did not develop arthritic changes some 30 years later. Our own laboratory work and clinical experience support their findings. I have long suspected that it is more likely that instability is more important than incongruity as we have documented in laboratory animals.^{65,103,113,124, 151}

It must be remembered that since many of these acetabular fractures are the result of violent impaction of the head of the femur against the acetabulum, the articular cartilage may be irreparably damaged from that moment on. Repositioning the displaced fragments under those circumstances does not change the pathological situation and osteoarthritic changes may ensue. I hope that in the near future we should be able, through imaging technologies, to critically assess the condition of the articular cartilage immediately after the injury, and in that manner design the most appropriate individual treatment.

Senior surgeons have recently reported that long-term follow-up of their patients indicates that those who had open reduction and internal fixation of the acetabulum developed painful arthritis and required total joint replacement sooner than those whose fractures were treated nonsurgically. One must assess these experiences very carefully. Lumping all fractures 4into a single package may lead to the wrong conclusions. There are, no questions about it, many fractures are definitely best managed by surgical means.

Surgically exposing severely comminuted acetabular fractures requires additional stripping of soft tissue attached to those fragments, bringing about the associated risk of devascularizing them even further and setting the stage for the development of heterotopic bone (Fig. 1.1).

In addition, even in the best of hands, anatomical reduction is not always attained, despite the fact that postoperative radiographs suggest otherwise. Gaps between the many fragments frequently remain. Plate and screws that are left behind may require major additional surgery at a later date when arthritic changes call for prosthetic replacement. Total hip replacement under those circumstances is more traumatic to perform, as it often requires the removal of the fixation devices. The greater the stripping of tissues, the greater the likelihood of heterotopic bone formation. Fixation with screws, without plating is advantageous.^{103,124,132, 151,160}

Despite some reports to the contrary, consideration must also be given to the nature of the original injury and the degree of initial displacement of the fragments. I suspect that a fracture produced through a high-energy mechanism behaves differently than one sustained from a fall to the ground after slipping on wet pavement.

I believe that certain acetabular fractures, particularly in the elderly, can be treated by nonsurgical means in anticipation that if arthritic changes occur, the situation could be remedied with an electively performed total hip replacement. Primary total hip replacement can be, on occasion, the treatment of choice. I have performed such a procedure a few times. However, I believe that under this circumstance, heterotopic bone is more likely to form. This also is true for acute fractures of the femoral neck treated primarily with total hip implants.

In the case of younger patients, surgery is not necessary in many instances. Comminuted fractures that show minimal incongruity and very mild step-off deformity are likely to lead to good results following nonoperative treatment (Figs 1.2 and 1.3). Fractures located over the less important weight-bearing area of the dome fall in that category. In the case of the elderly, there are many instances when the nonsurgical approach is the best one. If the patient survives the initial injury, the fracture heals in a few weeks. With appropriate precautions, such as special mattresses, balanced suspension of the injured extremity and good nursing care, survival may be increased. If at a later date, the joint becomes painful and conditions permit, an elective total hip replacement can then be performed.

Protection from significant weight-bearing for a few weeks (a period probably no longer than the one recommended after surgery following certain fractures) often restores the patient to a very acceptable degree of independence. With surgery or with conservative treatment, patients with these major fractures do not return to normal overnight. Pain can linger for some time.

Regardless of the type or location of the fracture, the presence of floating fragments in the joint (easily documented with CT scans) constitutes an ominous sign. If left in place, degenerative changes are likely to develop.

Patients with unstable fractures may develop protrusio that nonetheless may become asymptomatic or minimally symptomatic (Figs 1.4A to D).

Minimally displaced fractures of the sacrum with or without pubic or ischium fractures, and intact sacroiliac joints may be treated without surgery. A short period of nonweight-bearing ambulation usually suffices. On the other hand, those showing displacement and particularly those with the pathology located at the sacroiliac joint called for surgical stabilization.

Heterotopic bone develops in the overwhelming majority of instances only on the outer table of the iliac bone, even though stripping of periosteum and muscles is done on both tables. It may be speculated that the relative absence of heterotopic bone on the inner table is due to the effect of pulsatile peristalsis from the adjacent abdominal cavity; a mechanism that resembles the erosion of vertebrae adjacent to an aortic aneurysm. This is probably the same mechanism that explains why major vessels encased within solid masses of heterotopic bone are not obliterated; or bone grafts placed over the dura in spinal surgery do not grow further into the structure that covers the spinal cord. The constant pulsating circulation of the spinal fluid probably serves the same purpose of the pulsating arteries.