A Change in the Classical Order of Setting of Porous Metal Augments with Locked Cups in Hip Revision Surgery: Technical Note and Case Report.

Introduction: Reconstruction of acetabular bone defects by the combination of trabecular metal augments and porous cups can be complex when extensive bone loss and poor-quality bone exists. The onset of porous cups with an interlocking mechanism may simplify surgical technique due to its superior initial mechanical stability. We endorse the possibility for a change in the classical order of setting of the augments and the cup. Methods: We present a technical modification and a series of cases of three patients with Paprosky IIB and IIIA acetabular defects operated with a combination of porous metal augments and a porous cup. In all the three patients, the setting of the cup was done first and secured with locked screws, and then the augments were set in place as a wedge and fixed with screws in a standard fashion. Results: The postoperative X-ray showed good position of implants with restoration of the center of rotation, and the patients had good recovery. Radiological evaluation in the midterm follow-up did not show mobilization of implants. Discussion. The use of metal porous augments is widely used for severe acetabular defects, being a versatile system to adapt to the different size defects. Nevertheless, its use may be technically demanding and time consuming. It is not infrequent that the setting of the augments conditions the final position of the cup with a possible interference with initial stability and eventually bone ingrowth of the cup. The interlocking mechanism offers an additional biomechanical stability and thus may allow us to place the cup first in the desired position with a less demanding technique. Conclusion: With the use of locked-screw porous metal cups, the order of setting of implants may be changed in order to obtain a better restoration of the center of rotation and increased host-bone implant contact with a simplified surgical technique.

Difficulties associated with the variable geometry of different-offset Exeter long stems in cement-in-cement technique: A case report.

Although the cement in cement technique is a simple method for exchanging cemented stems, it may be technical demanding. The different geometry of different-offset Exeter long stems can be a problem with this technique. We describe a case revision hip surgery as a consequence of neglected bipolar hemiarthroplasty dislocation in which a 44 mm offset long stem was exchanged by a shorter and smaller size 37.5 mm offset stem. The implications of the procedure and the surgical pitfalls are discussed.

Microstructure and Surface Damage in Retrieved Metal-on-Metal Hip Arthroplasties.

BACKGROUND: Besides promising results of metal-on-metal (MOM) hip arthroplasty (HA), frequent failures have been reported even in the short term. Many host, surgical, design, metallurgical, and processing factors have been evoked in the base of these events. We have tried to characterize and to evaluate metallurgical and processing features present in this type of implants. METHODS: The acetabular and femoral components of 20 MOM HAs collected from a multicenter retrieval program were examined. All the specimens were inspected with naked eye, with confocal microscopy and vertical scanning interferometry, scanning electron microscopy, back-scattered electron imaging, and energy-dispersive X-ray spectroscopy, in 25 zones of each articular component. RESULTS: Gas pores, shrinkage voids and holes of detached carbides, carbides on surface, embedded particles, scratches and marks of wear, surface discoloration, surface deposits, and tribochemical reaction layers were widely dispersed through a substantial percentage of the total bearing surface in all the implanted components. Surface cup and head voids, and cup scratches showed significant correlation with the clearance of pair. A higher surface damage of the cup and head was observed mainly in the low clearance prostheses. There was no other significant correlation or difference in the incidence and importance of any of these defects between resurfacing hip arthroplasties and total hip arthroplasties, or according to the pair diameter. CONCLUSION: Some metallurgical features and surface damage were significantly present in the retrieved implants of MoM HAs. It would be desirable to improve the structure and metallurgical characteristics of these implants to avoid those effects and optimize their performance.

Traction injury of the brachial plexus confused with nerve injury due to interscalene brachial block: A case report.

INTRODUCTION: Shoulder surgery is often performed with the patient in the so called "beach-chair position" with elevation of the upper part of the body. The anesthetic procedure can be general anesthesia and/or regional block, usually interscalenic brachial plexus block. We present a case of brachial plexus palsy with a possible mechanism of traction based on the electromyographic and clinical findings, although a possible contribution of nerve block cannot be excluded. PRESENTATION OF THE CASE: We present a case of a 62 year-old female, that suffered from shoulder fracture-dislocation. Open reduction and internal fixation were performed in the so-called "beach-chair" position, under combined general-regional anesthesia. In the postoperative period complete motor brachial plexus palsy appeared, with neuropathic pain. Conservative treatment included analgesic drugs, neuromodulators, B-vitamin complex and physiotherapy. Spontaneous recovery appeared at 11 months. DISCUSION: in shoulder surgery, there may be complications related to both anesthetic technique and patient positioning/surgical maneuvers. Regional block often acts as a confusing factor when neurologic damage appears after surgery. Intraoperative maneuvers may cause eventual traction of the brachial plexus, and may be favored by the fixed position of the head using the accessory of the operating table in the beach-chair position. CONCLUSION: When postoperative brachial plexus palsy appears, nerve block is a confusing factor that tends to be attributed as the cause of palsy by the orthopedic surgeon. The beach chair position may predispose brachial plexus traction injury. The head and neck position should be regularly checked during long procedures, as intraoperative maneuvers may cause eventual traction of the brachial plexus.

Stoppa approach for intrapelvic damage control and reconstruction of complex acetabular defects with intra-pelvic socket migration: A case report.

INTRODUCTION: Failed hip arthroplasty with intrapelvic acetabular migration can be challenging due to the potential damage of intrapelvic structures. PRESENTATION OF THE CASE: We present a case of a 75 year-old lady with failed hip arthroplasty with loosening of implants and intra-pelvic migration of the cup, antiprotrusio cage mesh, screws and plate. A modified Stoppa approach was performed, a part of the migrated elements were safely removed, the intrapelvic structures were controlled, and the bone defect was reconstructed through the Stoppa approach combined with the lateral window of ilioinguinal approach by means of bone struts and metallic plates, which is a novel technique. Then an extended posterolateral hip approach was done and the acetabulum was reconstructed using porous tantalum augments and morselized allograft. A cemented constrained socket was implanted. After one-year follow-up the patient is able to walk with one crutch without pain. DISCUSSION: Due to intrapelvic migration, the implants used in hip arthroplasty may become entrapped between the anatomical structures lodged in the pelvis and cause damage to them. A careful preoperative assessment and planning are mandatory. A migrated socket can be inaccessible through a conventional hip approach and removal could be very difficult and dangerous. CONCLUSION: The Stoppa approach in hip revision surgery can be a complement to traditional approaches to control the intrapelvic structures, remove migrated implants of previous surgery and reconstruct the pelvic defect.

Extrarticular hip impingement.

Extrarticular causes of impingement have a current, interesting role in the complaint of groin pain in athletes. Subspine impingement is related to a prominent anterior inferior iliac spine (AIIS) and is actually described as a frequent cause of groin pain. Ischiofemoral impingement is described when the space between the lesser trochanter is decreased. Psoas impingement appears between the psoas tendon and the anterior labrum and anterior acetabular rim.

Longevity® constrained cup: an operative technical tip for prevention of metallic ring disassembly.

Constrained liners are a salvage procedure for treating or preventing recurrent dislocations. The Longevity® constrained liner (Zimmer) has a special design with cut-outs on its circumference for avoiding impingement in certain areas and a metallic constraining ring that has to be impacted. The ring impaction may be technical demanding. We recommend preassembly with the head component prior to seating into the acetabular cup, thus avoiding the soft tissue or cement interference and malposition due to bad angle of incidence of impaction force.

Femoroacetabular impingement and low energy posterior hip dislocation: a case report.

We report a case of a 28-year-old male who sustained an indirect injury of his left hip while playing soccer, which resulted in a posterior fracture-dislocation. Radiological examination showed signs of combined femoroacetabular impingement (FAI). We discuss the role of FAI as a risk factor for hip dislocation in low energy sport injuries.