Osteolysis and aseptic loosening currently contribute 75 % of implant failures. Furthermore, with over four million joint replacements projected to be performed in the United States annually, osteolysis and aseptic loosening may continue to pose a significant morbidity. This paper reviews the osteolysis cascade leading to osteoclast activation and bone resorption at the biochemical level. Additionally, the metal ion release mechanism from metallic implants is elucidated. Even though metal ions are not the predominating initiator of osteolysis, they do increase the concentration of key inflammatory cytokines that stimulate osteoclasts and prove to be a contributor to osteolysis and aseptic loosening. Osteolysis is a competitive mechanism among a number of biological reactions, which includes debris release, macrophage and osteoclast activation, an inflammatory response as well as metal ion release. Pharmacological therapy for component loosening has also been reviewed. A non-surgical treatment of osteolysis has not been found in the literature and thus may become an area of future research. Even though this research is warranted, comprehensively understanding the immune response to orthopedic implants and their metallic ions, and thus, creating improved prostheses appears to be the most cost-effective approach to decrease the morbidity related to osteolysis and to design implants with greater longevity. The ionic forms, cytokines, toxicity, gene expression, biological effects, and hypersensitivity responses of metallic elements from metal implants are summarized as well.

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Pectoralis major (PM) tendon tears are predominantly seen in young men, and the majority of tears occur as tendon avulsions involving the sternal head. Weightlifting, specifically bench-pressing, and sporting activities with eccentric overloading of the PM tendon are the 2 most common activities that result in PM injury.Early surgical repair or reconstruction should be offered to younger, active patients with a complete PM tear; the majority of the patients undergoing surgical repair achieve good-to-excellent outcomes.Nonsurgical treatment of a complete PM tear is an option but will result in cosmetic deformity and a deficit in adduction strength of the arm. Outcomes after nonsurgical treatment of complete PM tears are less satisfactory than those obtained after surgical treatment.Currently, there is no consensus on the chronological definition of PM tears (acute versus chronic), the critical time limit for performing surgical repair, the ideal fixation device (cortical button, bone tunnel, or suture anchors), the indications for allograft use, and the ideal rehabilitation protocol after treatment of PM tears.

In the patient with lateral hip pain, there is a broad differential diagnosis, making appropriate evaluation and management challenging. Greater trochanteric pain syndrome is a term used to denote chronic lateral hip pain and encompasses several painful soft tissue diagnoses including coxa saltans, trochanteric bursitis, and gluteus minimus and medius tendon tears. An overview of these common causes is presented through a series of cases that encompass the anatomic associations, classic presentations, diagnostic tests, and management strategies unique to each disorder. By reviewing this information, we hope to provide clinicians with the tools to evaluate greater trochanteric pain syndrome efficiently and effectively.

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While many femoral neck fractures can be reliably treated with surgical intervention, Pauwels III femoral neck fractures in the young adult population continue to be a challenging injury, and there is no consensus on optimal treatment. As such, there are past and ongoing biomechanical studies to evaluate the fixation provided by different constructs for this inherently unstable fracture. While many investigations rely on cadavers to evaluate the biomechanical performance of a construct, significant inter-subject variability can confound the analysis. Biomechanical femur analogs are being used more frequently due to more consistent mechanical properties; however, they have not been stringently evaluated for morphology or suitability for instrumentation. This study sought to determine the variability among composite femoral analogs as well as consistently create a Pauwels III injury and instrument the analogs without the need for fluoroscopic guidance. In total, 24 fourth-generation composite femoral analogs were evaluated for femoral height, neck-shaft angle, anteversion, and cortical thickness. A method was developed to simulate a Pauwels III fracture and to prepare three different constructs: an inverted triangle of cannulated screws, a sliding hip screw, and a hybrid inverted triangle with cannulated screws and a sliding hip screw. Radiographs were utilized to evaluate the variation in implant position. All but one of the morphological parameters varied by <1%. The tip-to-apex distance for all sliding hip screw hardware was 18.8 ± 3.3 mm, and all relevant cannulated screw distances were within 5 mm of the adjacent cortex. All screws were parallel, on average, within 1.5° on anterior-posterior and lateral films. Fourth-generation composite femora were found to be morphologically consistent, and it is possible to consistently instrument the analogs without the use of fluoroscopy. This analog and hardware implantation model could serve as a screening model for new fracture repair constructs without the need for cadaveric tissues or radiologic technology.

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