The continuous contact between the acetabulum and the femoral head-neck junction can cause a disorder of the hip joint called femoroacetabular impingement (FAI). This disorder causes damage on the articular cartilage and the acetabular labrum and can contribute to early osteoarthritis of the hip joint. It can also cause pain and restricts the range of motion of the hip joint.
The surgery for FAI can be performed open and arthroscopically, but the principles of this type of surgery remains the same – to correct the abnormal bony morphology on the femoral head-neck junction and acetabulum via an osteochondroplasty and rim trim, in order to repair or debride labral pathology associated with the lesion and to address chondral damage in the hip joint.
The resection of the femoral head and neck is often an important part of FAI surgery.
Post-operative hip fractures occur due to weakening of the femoral neck as a result of the resection that occurs during this procedure. A systematic review made by the Oxford Academy has also shown that, as the amount of resection during osteochondroplasty increases, the amount of energy required to fracture the femoral neck decreases.
However, there is no systematic review to date that has critically evaluated surgical and patient factors that lead to these fractures.
The goal of this systematic review, therefore, was to critically analyze both the clinical and basic science literature pertaining to this post-operative complication.
This study showed that the primary cause of a hip fracture following hip arthroscopy was a femoral osteochondroplasty combined with early weight bearing (before 6 weeks post-operatively). Some patients identified minor to moderate traumatic events that caused hip fracture during the early weight bearing.
Nevertheless, most patients that experienced a hip fracture due to early weight bearing after hip arthroscopy had no precipitating traumatic event. Less common causes of hip fracture after hip arthroscopy were also identified, including over-resection during femoral osteochondroplasty and intensive exercise.
This systematic review included basic science studies that regularly demonstrated there was a connection between increasing depth or resection and risk of fracture of the femoral neck. These studies also reported that it is safe to resect 10 to 33% of depth of the femoral neck before risk of fracture meaningfully increased.
Surgeons should be able to restore full range of motion of the hip without causing an increased risk of femoral neck fracture.
Results from the biomechanical studies must be interpreted with caution given the limitations of these types of studies and the fact that they did not take into consideration a number of patient factors, including varying bone densities.
Many studies did not specify the demographics of the patients that experienced a hip fracture as a complication, but the age factor appeared to correlate with increased risk of this complication.
There was no agreement in the literature as to whether males or females experienced higher rates of hip fractures as a complication of hip arthroscopy, just as there was no correlation between the number of hip arthroscopies a surgeon had performed and the rate of hip fractures as a complication.
This type of complication may be underreported as patients may present to a different surgeon and/or hospital after sustaining a hip fracture secondary to hip arthroscopy.
The available literature lacked demographic information regarding the patients who had experienced this complication, which made it difficult to conclude exactly which populations were most at risk for post-operative hip fractures.
Through this study, it was clear that early weight bearing after femoral osteochondroplasty was a large risk factor for hip fracture after a hip arthroscopy. Classical risk factors for hip fractures such as osteoporosis and rheumatoid arthritis are likely to be conditions that increase the risk of this complication and surgeons should bear this in mind when operating their patients.
Furthermore, the rate of hip fractures being caused by over-resection may have been underestimated.