Introduction Although arthroscopic procedures are less invasive than open surgical techniques, arthroscopy is not without complications. Complications of hip “scopes” may include traction-related nerve injuries, fluid extravasation, infection, osteonecrosis, and heterotopic ossification (HO). How to address and avoid these complications are the topics of this month’s “Case Connections” article. Ultrasound-Guided Pulse Lavage Treats Arthroscopy-Related HO In the August 27, 2014 JBJS Case Connector, Uquillas and Youm report on a fifty-one-year-old man who presented with symptoms consistent with right-sided femoroacetabular impingement (FAI). Radiographs revealed mixed cam and pincer impingement, and MRI showed an acetabular labral tear, spurring of the acetabulum and femoral neck, a loose body, and chondral delamination. Surgeons used hip arthroscopy to address these multiple problems. Six months after the procedure, the patient had developed increasing lateral hip pain and tightness. At the eight-month follow-up, he reported a sharp spike in hip pain and showed mild impingement signs. Radiographs revealed HO near the greater trochanter, a finding validated by CT (Fig. 1). MRI revealed inflammation surrounding the area of heterotopic bone.Fig. 1: Three-dimensional CT reconstruction showing heterotopic ossification near the greater trochanter.After a year of ineffective anti-inflammatory medication and physical therapy, interventional radiologists performed an ultrasound-guided pulse lavage (1% lidocaine followed by saline solution) to irrigate and debride the 1.3 × 0.08 × 1.1-cm calcific deposit that had been observed on a preprocedure ultrasound. Dispersion of the deposition was noted during the procedure, which was followed by a steroid/anesthetic injection to provide immediate pain relief and treat inflammation. The patient reported complete pain resolution following the procedure, and six months later, he remained pain-free and showed no signs of impingement. Radiographs confirmed no recurrence of HO. Citing recent literature that puts the incidence of HO after hip arthroscopy in the range of 4.7% to 12.1%, Uquillas and Youm note that most such cases are asymptomatic. However, focal excision may be warranted when pain impairs function. Excision is typically achieved through open or arthroscopic techniques, but the authors conclude that advancements in ultrasound now make guided pulse lavage a possible treatment choice for small symptomatic HO lesions. Intravasation of Arthroscopy Fluid Causes Pulmonary Edema Pulmonary edema resulting from arthroscopic procedures is rare, but Trivedi et al. reported on such a case in a fourteen-year-old boy who was being treated arthroscopically for cam impingement related to a slipped capital femoral epiphysis (SCFE). A month after stabilizing the SCFE with in situ screw fixation, surgeons performed hip arthroscopy with the irrigation-fluid pressure set at 55 mm Hg. After completing an anterior capsulotomy, surgeons noted profuse bleeding from the cannula in the anterolateral portal. To improve visualization of the peripheral compartment, they blocked the fluid-outflow port manually. They observed no intra-articular bleeding but did notice that the fluid pump ran continuously despite the outflow ports being closed. There was no swelling in the abdomen or the ipsilateral thigh suggestive of extravasation, but minutes later the patient’s systolic and diastolic blood pressure doubled, and a large volume of pink fluid was expelled from the endotracheal tube. A diagnosis of pulmonary edema was made. The arthroscopic procedure was abandoned; the patient was resuscitated with furosemide and fluid restriction and then transferred to the ICU, where the hypertension gradually resolved. He was extubated two days after the procedure, and a cardiac workup showed no heart or vessel abnormalities. He was discharged and eventually underwent an open femoral neck osteoplasty, which he tolerated without complication. In reviewing this case, the authors ruled out other possible iatrogenic causes of the pulmonary edema, including an adverse response to epinephrine in the irrigation fluid, increased intramedullary pressure, negative-pressure pulmonary edema, and anaphylaxis. They concluded that in this patient, the most likely mechanism of pulmonary edema was “circulatory stress imposed by high-pressure irrigation with normal saline solution in a short period of time.” They surmised that the copious bleeding noted early in the procedure was related to arterial or venous injury, which could have provided circulatory access for the irrigation fluid. Because pump-driven arthroscopic irrigation systems may increase the risk of fluid extravasation, the authors concluded by saying that “orthopaedic surgeons and anesthesiologists should be aware of the causes, presentation, and complications of acute pulmonary edema,” and that prompt treatment of this condition is crucial. Avoiding Arthroscopy-Related Hip Dislocation Anterior hip dislocations are usually caused by a high-energy force applied to the posterior part of the proximal femur. In addition to trauma, risk factors for such dislocations include ligamentous laxity and, according to a case reported by Ranawat et al., a prior hip capsulectomy. In this case report, a fifty-two-year-old woman presented with a two-year history of right groin pain and “popping” in the right hip. Physical examination revealed hyperextension of both hips; with axial traction, the right hip was easily distracted 1 to 2 cm. The patient had undergone bilateral capsulorrhaphy for shoulder instability several years prior to presentation, although she had never been tested genetically for a collagen disorder. Hip radiographs showed no evidence of degenerative changes, dysplasia, or FAI, but a magnetic resonance arthrogram showed a peripheral tear of the anterosuperior part of the labrum. An intra-articular steroid/anesthetic injection provided short-term symptomatic relief, but after six weeks the symptoms returned. The patient then underwent arthroscopic treatment for the labral tear and capsular laxity. To improve peripheral-compartment visualization, surgeons performed a partial capsulectomy, and a previously undetected cam-type impingement lesion was identified intraoperatively. Surgeons performed a femoral osteochondroplasty to alleviate impingement and protect the labral repair, followed by plication of the anterior capsule, including the iliofemoral ligament. The patient wore a hip orthosis for six weeks, at which point she was progressing well and was told she could bear full weight on the right leg. However, two months later she fell with the affected leg in extension. Emergency room physicians diagnosed an anterior hip dislocation with no apparent fractures and performed a closed reduction. A nonoperative postreduction regimen that included physical therapy did not yield substantial pain relief; therefore, the authors performed a revision arthroscopy. During the revision, they identified a 2-cm tear of the anterior capsule and iliofemoral ligament in the region of the prior capsulectomy. This time, surgeons plicated both the central and peripheral compartments. The patient used a knee-ankle-foot orthosis for eight weeks after the procedure; at the six-month follow-up, she reported only occasional pain. There was no radiographic evidence of osteonecrosis. This case highlights the potential consequences of violating the iliofemoral ligament during peripheral compartment arthroscopy. The authors have since become “reluctant to perform a capsulectomy in patients with capsular laxity,” and when performing arthroscopic osteoplasty, they “make the smallest possible capsulectomy that still provides adequate visualization of the proximal part of the femur.” They also recommend a more conservative postoperative rehab protocol in these cases, with protected weight-bearing and bracing for as long as eight weeks. Conclusions Arthroscopic techniques for the hip are unique and require appropriate surgical education and experience, as well as an understanding of the substantial learning curve. In order to avoid complications, younger surgeons are advised to work with more experienced hip arthroscopists for a longer period of time. Even experienced hip arthroscopists can encounter rare systemic complications during this procedure. Frequent communication with the anesthesia team and vigilance will help avoid patient injury due to vascular or pulmonary compromise. Heterotopic bone is a rare complication, as is postoperative hip dislocation; two of the unusual cases summarized here offer advice regarding prevention and treatment of these rare occurrences.