Abos Day 46 A 1-3

Front 1

18yo B w/ severe hip OA & pn from a missed SCFE. recommd hip arthrodesis. What optimum position for hip arthrodesis maxi functn & prevent complctns? 1-0°ER, 0° add, 0° flex; 2-5°ER, 0° add, 20° flex; 3-5° ER, 15° abd, 5° flex;

Back 1

4-15°ER, 0° add, 20° flex 5-15° ER, 15° abd, 5° flex::Hip arthrodesis-salvage procd for pts w/ hip DJD w/out ipsl knee, contralat hip, lumbr spine path. optimal position= 0-5 add, 0-5 ER & 20-35 flex. Add ,5 ER 5 flex2x(sum of 10)=20Ans2

Front 2

73yo F gets a (THA) cemented stem Fig A. RTC 3 yrs post-op w/ signfcnt thigh pain. Current xrays Fig B, show fem subsidence. What affect does this have on the biomech of THA?1-Excursion distnc dec; 2-Primary arc range inc
3. Abductor complex tension is decreased
4. Joint reactive forces are decreased
5. Femoral offset is increased

Back 2

3-Abd complex tension is dec; 4-Jnt reactive forces are dec; 5-Fem offset is inc::Fem stem subsidence effectively dec nck lngth of the prosthesis -> lax abd complex -> in-> jnt reactive force. dec LL -> inc hip instability.Ans3

Front 3

All are independent risk factors for dislocation p/ THA EXCEPT? 1-F gender; 2-Osteo necrosis; 3. Inflam arthritis
4. Post traumatic OA; 5- Age >70

Back 3

incidence dislctn: highest in 1 yr p/ surgery & then continues =relativly const rate for life Aplasty. pts highest risk: F pts, dx AVN head, acute fx/ nonun prox fem tx w/ THA, hx inflamm aurthr, age >70.Ans4

Front 4

68yo M 2 wks s/p L THA experiences-painful clunk gettg out of bed in AM, unable WB L leg. xray fig A. Followg CR hip contns dislct w/ flex >90 deg. Each operative interventions inc stability hip EXCEPT: 1-Revising acetblr to >med'd posin;

Back 4

2-Advancing trochanter dis -> fem; 3-Converting fem compnt w/ extnd offset; 4-Replacg acetablr polyethylene w/constrained liner; 5-Replacg fem hd w/ a larger sz;;Medlzg acetabulum dec lever arm abd -> redcd ST tensng, >laxity, thus dec stability.Ans1