Ortho Oracle - orthopaedic operative atlas

Metastastic Lymphoma

– Discussion:     – bone scans tend to be hot (unlike multiple myeloma);     – bone lesion may be less likely to cause pathologic fractures than other metatsatic lesions;     – if bone lesions are asymptomatic, consider non operative treatment;     – associated features include lymphadenopathy or splenomegaly;            – evaluate cervical, … Read more

Metastastic Prostatic Bone Carcinoma

Discussion:     – pathologic fractures through lesions w/ increased density is rare;     – lesion should be irradiated if the patient has pain, & internal fixation is indicated only if the pain persists after completion of the irradiation              and no other cause is found;     – PSA:         … Read more

Metacarpal Shaft Frx

    – Discussion:     – displacement of metacarpal shaft fractures is prevented by intermetacarpal ligaments and intrinsic muscles;     – the border metacarpals (thumb, index, and little) are not supported as well as the ring and long metacarpals and are therefore more likely to displace;     – effect of shortening:     … Read more

Metal Fatigue

– See: Characteristics of Metals and Implants: – Fratigue Fracture:     – frx or break or a metal caused by repetitive applications of loads in between the fatigue limit and the Yield Strength; – Fatigue Limit:     – load that a metal can endure indefinitely without bending or breaking when subjected to cyclic bending; … Read more

Metal on Metal Total Hip Replacement

– Advantages:      – larger heads helps avoid dislocation:     – avoidance of screws     – larger heads allows greater ROM – Disadvantages:      – metallosis      – contraindictated in renal insufficiency; – Levels:      – normal cobalt:            – mean serum cobalt level of 0.24 µg/L (range: 0.08 to 0.50 µg/L)            – highest safe level: … Read more

Metallurgy: TKR

– Discussion:  – femoral component is made of chrome colbalt alloy w/ its proven wear characteristics articulating with high density poly ethylene;  – tibial & patella components are metal backed w/ titanium alloy;  – enhance fatigue strength of titanium decreases potential for stress fracture of the metallic tibial tray;  – in metal back patella component, the … Read more

Metaphyseal Artery

– See:       – Epiphyseal Artery       – Nutrient Artery       – Periosteal Artery – Discussion:     – metaphyseal portion of long bone contains numerous small channels;     – through these channels pass vessels that enter marrow cavity to anastomose w/ vessels derived from nutrient artery;     … Read more

Metacarpal Extra-articular Base Frx

– See: Extra-articular Thumb Metacarpal Fractures – Discussion:     – interosseous muscles & intrinsically strong carpometacarpal capsular and interosseous ligaments provide intrinsic stability to extra-articular fractures at the metacarpal bases;     – mechanism of frx of little CMC:           – stability of CMC joint derives from articulation w/ carpal … Read more

Metacarpal Head Fractures

– See: MP joint injuries – Discussion:     – often badly comminuted;     – consider a short period of splinting followed by early active motion;     – this may mold the articular surface by using the soft tissue sleeve;     – early motion will also prevent joint stiffness, but loos of … Read more