Spontaneous modular femoral head dissociation complicating total hip arthroplasty.

Modular femoral heads have been used successfully for many years in total hip arthroplasty. Few complications have been reported for the modular Morse taper connection between the femoral head and trunnion of the stem in metal-on-polyethylene bearings. Although there has always been some concern over the potential for fretting, corrosion, and generation of particulate debris at the modular junction, this was not considered a significant clinical problem. More recently, concern has increased because fretting and corrosive debris have resulted in rare cases of pain, adverse local tissue reaction, pseudotumor, and osteolysis. Larger femoral heads, which have gained popularity in total hip arthroplasty, are suspected to increase the potential for local and systemic complications of fretting, corrosion, and generation of metal ions because of greater torque at the modular junction. A less common complication is dissociation of the modular femoral heads. Morse taper dissociation has been reported in the literature, mainly in association with a traumatic event, such as closed reduction of a dislocation or fatigue fracture of the femoral neck of a prosthesis. This report describes 3 cases of spontaneous dissociation of the modular prosthetic femoral head from the trunnion of the same tapered titanium stem because of fretting and wear of the Morse taper in a metal-on-polyethylene bearing. Continued clinical and scientific research on Morse taper junctions is warranted to identify and prioritize implant and surgical factors that lead to this and other types of trunnion failure to minimize complications associated with Morse taper junctions as hip implants and surgical techniques continue to evolve.

Arthroscopic ligamentum teres reconstruction.

The ligamentum teres (LT) has been studied since the 19th century, and its anatomy and biomechanical function have been well described. Recent advancements in hip arthroscopy have caused increased awareness of LT pathology. Previous reports have estimated the incidence of LT tears during hip arthroscopy to be 4% to 51%, and LT tears have been estimated to be the third most common reason for hip pain in athletes. Biomechanical studies have shown the LT's role in stability of the hip. Despite the growing body of literature on LT anatomy and function, its role as a causative factor in hip pain and hip instability has yet to be clearly defined, and the treatment of LT tears remains controversial. However, in certain cases where hip subluxation and overt instability are related to a traumatic full-thickness tear of the LT, reconstruction of the ligamentum has been suggested. We describe a technique for arthroscopic LT reconstruction using either a semitendinosus autograft or allograft in the supine position.

Endoscopic repair of proximal hamstring avulsion.

Hamstring muscle injuries are common in athletes and mostly consist of sprains at the myotendinous junction, which often respond well to conservative treatment. Proximal hamstring avulsion injuries, though less common, can be severely debilitating. This injury is often seen in water skiers but has been described in many other sports and in middle-aged patients. Complete avulsions in young and active individuals do not respond well to conservative treatment and may require surgical repair. In contrast, many partial tears may be treated nonoperatively. However, when symptoms continue despite a trial of extensive therapy, surgery may be warranted. Traditional surgery for proximal hamstring repair is performed with the patient in the prone position with an incision made longitudinally or along the gluteal fold, followed by identification of the torn tendons and fixation to the ischial tuberosity. We describe a novel surgical technique for endoscopic repair of proximal hamstring avulsion injuries.