Periacetabular osteotomy (PAO) has come to the forefront as the pelvic osteotomy of choice in North America and Europe for treating the dysmorphic acetabulum. PAO is currently indicated as the preferred treatment for patients with symptomatic hip dysplasia and has a role in treating patients with acetabular retroversion and protrusio. The acetabular deformity commonly is associated with labral pathology and deformities in the shape of the femoral head and head-neck junction. In 1999, Myers et al.  recommended open arthrotomy at the time of the PAO to treat the concomitant labral pathology and to perform an osteochondroplasty of the femoral head and neck junction. Simultaneous arthrotomy allows the surgeon to assess intraarticular abnormalities and hip motion and impingement after reorientation of the acetabulum.
The surgical technique used to perform the arthrotomy may be an important variable in relief of pain, restoration of function, and durability of the reconstruction, and described techniques are varied. Assessing labral pathology is difficult unless traction is applied on the leg. Some surgeons use manual traction to inspect the acetabular rim and labrum while others routinely use a fracture table or other similar traction table to distract the joint and enhance access to any intraarticular pathology. The use of an arthroscope without fluid, the so-called dry-scope technique, can further enhance visualization and improve the assessment and treatment of the acetabular labrum and cartilage. Regardless of the technique used, the risks of open arthrotomy should be weighed against its benefits. For most surgeons, opening the joint capsule requires detachment of the direct head of the rectus off the anterior inferior iliac spine and exposure of the iliocapsularis muscle off the anterior capsule. This increased surgical exposure, along with potentially increased operative time, could lead to complications, including formation of heterotopic ossification, scarring, or other undesirable consequences such as formation of adhesions between the femoral head-neck junction and capsule that could lead to groin pain.
Whether an open arthrotomy should be performed at the time of PAO remains controversial due to a lack of data and consensus in the literature. However, at this time, it seems most surgeons who perform a relatively high volume of PAOs prefer routine arthrotomy.
Several studies have failed to demonstrate improvement in pain and function as a result of arthrotomy at the time of PAO. Troelsen et al.  reported a greater than 80% survivorship at 9.2 years without routine arthrotomy. Matheney et al.  reviewed 189 hips in 157 patients treated with a PAO. Since 23 were lost to followup and 31 had diagnoses other than developmental dysplasia of the hip, 135 of the 189 hips in 109 patients were reviewed at an average of 9 years. Eleven percent of patients (135 hips) had a subsequent hip arthroscopy at an average of 6.8 years. All but one patient had received an open arthrotomy at the time of PAO, suggesting performing the arthrotomy did not necessarily protect against future reoperation.
On the other hand, there are increasing data from several other studies suggesting simultaneous arthrotomy improves outcomes associated with PAO. The initial experience with PAO from Bern, Switzerland, when routine arthrotomy was not performed for assessment of impingement or labral pathology, demonstrated more pain in patients with labral pathology and need for reoperation in two patients in whom an attempt of labral refixation was performed at the time of the primary PAO . Similarly, in a consecutive series of PAOs, Albers et al.  demonstrated survival was improved once arthrotomy was routinely performed. Seventy-five hips were operated on before routine arthrotomy and 90 hips with routine arthrotomy and inspection for and correction of identified impingement. Fifty of 90 hips (56%) received osteochondroplasty of the femoral head-neck junction. The cumulative 10-year survivorship was better in the arthrotomy group than in the nonarthrotomy group (86% versus 77%). Their study emphasized the importance of the three-dimensional orientation of the acetabular fragment and the maintenance of impingement-free ROM. Finally, Peters et al.  have recently updated their original results after PAO, considering the influence of arthrotomy. In the group of 149 PAOs performed with routine arthrotomy, 85% received a head-neck offset restoration procedure and 21% received treatment of identified labral pathology. There were fewer failures, defined as conversion to THA or repeat PAO, in the group of PAOs performed with concurrent arthrotomy compared to the group that did not receive an arthrotomy (5% versus 17%), although the preoperative and postoperative Harris hip scores were similar between the two groups.