APGAR FAMILIAR
CONSIDERACIONES ÉTICAS
Nashat Siddiqui and Phil Kerr
MCQs
1. a. No difference between AVN and non-union rates.
Although it is common to treat these fractures with some urgency, a meta-analysis of 18 studies (564 fractures) showed no difference in these rates if surgery is carried out before or after 12 hours. A further study has shown no difference before or after 48 hours.
2. a. Inferior gluteal.
The inferior gluteal artery may retract into the pelvis, requiring the patient to be positioned supine and urgent laparotomy to tie off the internal iliac artery.
3. d. Blood transfusion is more likely with the use of drains.
In a Cochrane review of 36 studies (5697 surgical wounds), no statistically significant difference was found in the occurrence of infection, haematoma, dehiscence, or re-operation between patients with or without suction drains. Those with drains had a higher rate of transfusion, but lower rate of wound dressing reinforcement and bruising.
4. c. Medial circumflex artery.
The medial circumflex artery is a branch of the profunda femoris, originating from the external iliac. The blood supply is via subsynovial retinacular artery. The remainder is supplied by the artery of ligamentum teres (obturator artery) and lateral circumflex artery (profunda femoris).
5. a. Gluteus minimus and tensor fascia lata.
Gluteus minimus inserts anteriorly on the tip of greater trochanter, but gluteus medius inserts more posteriorly and therefore is more of an external rotator than minimus. Piriformis is, of course, an external rotator. Tensor fascia lata originates from the iliac crest and anterior superior iliac spine (ASIS) and via its attachment to the iliotibial band, acts as an internal rotator, abductor and flexor of the hip. Iliopsoas, which attaches to the lesser trochanter, is primarily a flexor of the hip. Although it is responsible for the externally rotated position of the femur in patients with femoral neck fractures, thereby acting as an external rotator of the hip, it does not have any significant rotational contribution in the uninjured femur.
6. b. Posterior wall and anterior column of the right acetabulum.
Judet views of the pelvis are: Obturator oblique, where the obturator foramen on that side is parallel to the X-ray cassette, by elevating the pelvis on that side, and shows the posterior wall and Postgraduate Orthopaedics, ed. Kesavan Sri-Ram. Published by Cambridge University Press.
# Cambridge University Press 2012.
anterior column of the elevated acetabulum (mnemonic: OOPWAC– Obturator Oblique Posterior Wall Anterior Column), but not the sacroiliac joint so well; and Iliac oblique, where the pelvis on that side is rotated so that the iliac wing is parallel to the X-ray cassette and the obturator foramen now lies perpendicular to the film, showing the anterior wall and posterior column.
7. b. FICAT II.
As long as the femoral head is in the pre-collapse phase and has minimal involvement (<30% ideally) core decompression is likely to be beneficial. Results are still not fully conclusive, but current thinking is that pre-collapse heads may be decompressed
successfully, but once the collapse (crescent sign, FICAT III) has appeared, salvage is not possible in this way. Whether or not there should be addition of other products such as bone morphogenic protein or growth factors is still controversial.
8. c. There is a known organism from preoperative aspirate and the patient has commenced antibiotics.
Selected patients may undergo single-stage revision, with reported better functional outcome than two-stage revisions. The prerequisites for this are healthy soft tissues, minimal bone loss allowing for cement to be inserted, and a known pathogen with sensitivities. Significant severe bone loss, an unidentified pathogen and the presence of multi-resistant bacteria are contraindications to single-stage revision surgery.
9. d. Valgus deformity of femoral neck.
All the above are seen due to remodelling of bone and high vascularity, except a valgus deformity. Typically, varus deformity is seen due to initially osteoporotic change which causes deformity under loading before remodelling into its final shape; this is also responsible for anterolateral diaphyseal bowing. Stress fractures may also be seen on the convex side of the femoral diaphysis. Bone may have lytic lesions or be unusually dense, depending on the activity of the disease process.
10.e. Pressure from straps of abduction wedge pillow.
Straps from an abduction wedge pillow may cause local pressure to the common peroneal nerve, rather than the sciatic nerve, at the level of the fibular neck resulting in foot drop. The most commonly injured part of the sciatic nerve is the region which goes on to become the common peroneal nerve. In one study, peroneal palsy was found more commonly after average lengthening of 2.7 cm and sciatic palsy with average lengthening of over 4.4 cm.
11.d. They are associated with degenerate changes and cysts when due to femoro-acetabular impingement.
Labral tears are often associated with subtle abnormalities of hip anatomy causing femoro-acetabular impingement (FAI). Painful clicking, snapping and similar symptoms are often due to labral tears in association with FAI. Labral tears may present as groin pain usually in certain positions and repetitive movements such as running.
12.a. Infection is within 3 weeks of surgery.
Phillipset al found 41% of infections were successfully treated with debridement and antibiotics. Crockarellet al. found debridement successful only if performed within 2 weeks of onset of symptoms.
Chapter 5– Hip and pelvis: Answers
13.b. Lesser trochanter group.
There are four main trabecular patterns in the proximal femur. There are two compressive, one tensile, and one greater trochanteric group but none relating specifically to the lesser trochanter.
14.c. Compression of the lateral cutaneous nerve of thigh.
The lateral cutaneous nerve of thigh may typically be compressed at several locations, such as the inguinal ligament, by tight belts (e.g. weightlifter’s belt), resulting in pain in the anterolateral part of the thigh.
15.a. Previous formation of heterotopic ossification.
Although the exact aetiology is poorly understood, if there is a history of heterotopic ossification, then it is very likely to recur at a new site of surgery. Other factors include:
ankylosing spondylitis, hypertrophic osteoarthritis, and diffuse idiopathic skeletal hyperostosis, with weaker evidence for extensive soft tissue handling/stripping, or bone debris from reamings. Although patients with head injuries are found to produce extensive calcific deposits a patient would not have elective total hip replacement so soon after significant head injury. Over-expression of bone morphogenetic protein-4 BMP-4) may be implicated in the pathogenesis of heterotopic ossification.
16.d. Continued as usual.
Although there is a higher rate of infection in general in rheumatoid patients, continuing their methotrexate at the normal dose has not been shown to affect their risk of infection.
Grennanet al found that methotrexate made no difference to early infection following elective orthopaedic surgery when two groups were compared, one which continued and a group that didn’t; other drugs such as penicillamine, indomethacin, ciclosporin,
hydroxychloroquine, chloroquine and prednisolone did increase the early infection risk post-operatively. Conversely, discontinuing their methotrexate may result in disease flare that impedes their post-operative rehabilitation.
17.d. Hip aspiration.
Although a radio-labelled white cell scan is more likely to be positive in infection rather than inflammation, it cannot be used to definitively differentiate between the two.
A radionuclide bone scan would appear hot in both conditions. A positive hip aspirate would both identify infection, as well as guide antibiotic treatment. Von Rothenburg et al found a Tc-99m-labelled scan had sensitivity of 93% but specificity of 65%.
Therefore, a positive result (positive predictive value 63%) may not definitely mean an infection, whereas a negative result (negative predictive value 94%) is likely to help rule out infection.
18.a. It is best with a polished tapered stem.
Polished tapered stems such as the Exeter stem are best suited to impaction grafting, as subsidence is expected. This is thought to allow subsidence in the cement mantle, and subject the cement to creep, thereby distributing load evenly and encouraging bone to remodel. Although earlier studies have waned against subsidence, Wraighteet al showed that there was no link between subsidence (median 2 mm at 1 year; up to total 10 mm in some patients) and 10-year survival.
Chapter 5– Hip and pelvis: Answers
19.b. Reduce dislocation by a magnitude of 10.
Although there are many studies, most conclude that there is a beneficial effect of repairing the posterior soft tissue structures. A meta-analysis by Kwonet al found that the rate of dislocation reduced from 4.46% to 0.49% if repaired.
20.e. Thickness of HA of at least 50 mm.
Although all these factors are important when considering cementless fixation, they are not all relevant to hydroxyapatite-coated stems, and apply also to other stems such as porous-coated and grit-blasted stems. In a canine model, it has been shown that there is greater total bone apposition and bone ingrowth in implants coated with minimum 50mm hydroxyapatite at the level of the isthmus and the calcar, although there was no difference between having 50 or 100mm thickness coating on the amount of bony ingrowth.
21.d. Femoral head/neck junction prominence.
The patient is likely to be suffering from cam-type femoro-acetabular impingement, often presenting secondary to DDH, Perthes, or slipped upper femoral epiphysis, with a head/
neck junction prominence that may also lead to labral degeneration, cysts and tear.
Degenerate changes at the articular surface in mild DDH is rare in a patient of this age, although cysts may be seen at the head/neck junction if there is impingement.
22.e. Remove metalwork, insert cemented stem passing two cortical thicknesses below lowest screw hole.
There is no need to reinforce the femur externally. A well-cemented stem must pass well past the lowest screw hole to reduce the risk of a stress riser. Hip resurfacing in a patient of this age is not recommended.
23.a. Less in ceramic than polyethylene cups.
The Swedish Hip Registry reports that deep infections are slightly lower with ceramic components. The exact mechanism is unclear, but may be due to bacterial adhesion being poorer on the smoother surface of ceramic components.
24.d. If less than 15º, it is one of the indications for pelvic osteotomy.
This is the angle between a vertical line through the centre of the femoral head and a line connecting the centre of the femoral head to the edge of the acetabulum, used in patients over the age of 5, and useful in adults. Greater than 25º is considered normal, and less than 20is considered a dysplastic acetabulum. Less than 15º is marked dysplasia, and the patient may benefit from osteotomy of the acetabulum.
25.e. Vascularized fibular graft.
As long as there is no collapse of the femoral head, vascularized fibular graft has been shown to be superior to non-vascularized by reducing progression to collapse, as well as having better Harris Hip Scores.
26.c. Lateral cutaneous nerve of thigh.
The ilio-inguinal approach is an exam favourite. It affords exposure to the inner aspect of the pelvis from the sacroiliac joint all the way to pubic symphysis. The lateral cutaneous nerve of thigh often is in the way and must be sacrificed. Although infrequently used by
Chapter 5– Hip and pelvis: Answers
most surgeons, it would be worth memorizing the concepts of this approach, particularly the structures at risk in the three‘windows’: Lateral – between the iliac wing and the iliopsoas muscle; Middle– between the femoral nerve (iliopsoas muscle) and the external iliac vessels; Medial– between the lymphatics and the rectus abdominus at the level of the pubic tubercle.
27.e. Hydrodynamic.
Although the majority of lubrication in total hip replacements is boundary lubrication, hard-on-hard bearing surfaces, such as metal-on-metal, have been found to have
hydrodynamic lubrication during the motion phase of the gait cycle, particularly effective when the prosthesis is polar bearing with high conformity.
28.b. Multiple emboli.
Donaldsonet al have attempted to define this poorly understood phenomenon:“BCIS is characterized by hypoxia, hypotension or both and/or unexpected loss of consciousness occurring around the time of cementation, prosthesis insertion, reduction of the joint or, occasionally, limb tourniquet deflation in a patient undergoing cemented bone surgery.” Current thinking on aetiology leans towards multiple embolic showers of fat, marrow, cement particles, air, bone particles and platelet/fibrin aggregate. Previous theories of methylmethacrylate monomers entering the circulation and causing significant vasodilatation have now largely been discounted in favour of the embolic theory.
29.c. Gluteus maximus and adductor magnus.
The sciatic nerve passes through the interval between piriformis and superior gemellus to lie under gluteus maximus, and passes over the gemelli, obturator internus, and quadratus femoris, before passing over the posterior surface of adductor magnus until it divides into its terminal branches. Cross-sectional anatomy of the limbs at different levels is a popular exam question, and it is worth memorizing the major structures in relation to each other.
30.e. Inwardly displaced parasymphyseal fracture >1 cm.
The single biggest predictor of urethral injury is pubic symphysis diastasis, especially of>1 cm, along with medially displaced medial 1/3 fracture. However, inward displacement didn’t result in a large number of patients having urethral injury. It would appear that the traction caused to the urethra is more significant than compression.
Chapter 5– Hip and pelvis: Answers
EMQs
1. 1.d. Gluteus maximus and gluteus medius. 2. i. Rectus abdominis. 3. f. Inguinal ligament.
Although in reality most of us will rarely use the approach to the pelvis, it is an exam favourite. The Kocher–Langenbeck approach is an extension of the posterior approach to the hip but with elevation of gluteus maximus from the femur, and gluteus maximus and medius from the posterior and lateral ilium, taking care with the superior and inferior gluteal neurovascular bundles. The anterior approach to the pubic symphysis utilizes a curved transverse incision above the symphysis and divides both rectus abdominis muscles entirely, but due to a segmental nerve supply they are not denervated. The bladder lies immediately posteriorly to the pubic symphysis, separated by the space of Retzius. The inguinal ligament, if damaged at its attachment at the anterior superior iliac spine (ASIS), may result in an inguinal hernia, so anterior crest harvesting should not be extended so low.
2. 1.a. 1, 2, 3. 2. e. 6, 7. 3. g. 3, 4, 5.
Gruen zones for femoral stem loosening are 1–7, starting laterally at the greater trochanter and working inferiorly and medially to end at the calcar.
Delee and Charnley zones for acetabular cup loosening are 1–3, commencing at the lateral acetabulum and working medially.
3. 1.g. Chiari. 2. h. Shelf. 3. a. Ganz.
It is worth knowing the main pelvic osteotomies in relation to the age they are performed, indication, whether they are reconstructive or salvage, and the basics of which bones are osteotomized. The Chiari and shelf osteotomies are both salvage procedures, relying on the femoral head being contained in a‘pseudo’-acetabulum; whereas the Ganz osteotomy is technically very challenging but can reorientate the acetabulum very well.
4. 1.b. 25–30º. 2. c. 0–5º. 3. c. 0–5º.
The hip should be in a flexed position to aid ground clearance and sitting position; and avoiding abduction, otherwise an abduction lurch will result. The hip should be in neutral or slight external rotation to allow for pelvic translation during gait.
5. 1.c. Calcar pivot. 2. e. Bending cantilever. 3. a. Pistoning: stem and cement within bone.
Five modes of femoral stem loosening and seven zones of loosening have been described.
Calcar pivoting of the stem results in the stem toggling more medially from its original position, i.e. zone 4 at tip and zone 5 medially. Cantilever bending demonstrates good distal fix but toggling mediolaterally at the proximal end. With stem and cement moving as one and pistoning in and out of the bone, all seven zones must be loose; this is different to the stem moving within a fixed cement mantle, which may only show zones 1 and 2 loosening with a distal cement fracture and distal migration of the stem as a result.
6. 1.e. Rectus femoris. 2. f. Hamstrings. 3. j. Sartorius.
Avulsion injuries are being diagnosed more frequently, occurring mainly in adolescents.
The mainstay of treatment is non-operative. They usually result in a return to full activity, Chapter 5– Hip and pelvis: Answers
power and range of movement within a matter of weeks. Large fragments which are significantly displaced or have developed into non-union may occasionally need internal fixation.
7. 1.e. Urgent/semi-elective internal fixation. 2. c. Non-weight-bearing for 2 weeks, then gradual increase in weight-bearing. 3. c. Non-weight-bearing for 2 weeks, then gradual increase in weight-bearing.
Fullerton and Snowdy have classified such stress fractures into type A (lateral/superior neck, under tension), requiring screw fixation; type B (medial/inferior neck, under compression), treated with rest followed by protected weight-bearing; and type C (displaced), requiring internal fixation/replacement as appropriate.
8. 1.d. Labral tear. 2. f. Hamstring avulsion. 3. c. Iliotibial band syndrome.
Iliotibial band syndrome may present as severe snapping at the lateral aspect of the hip, patients may describe the hip feeling as if it has dislocated in severe instances; worse in females with prominent trochanters and running on banked surfaces. Hamstring tears/
avulsions are due to sudden contractures, such as sprinting. Labral tears often present in young patients with no trauma; groin clicking is a sensitive symptom, but may also be frequently caused by iliopsoas over the hip joint.
9. 1.a. Porosity reduction using a vacuum. 2. f. Pulsatile lavage. 3. d. Finger packing.
First generation involved finger packing with no canal preparation or pressurization of cement. Second generation techniques introduced pulsed lavage and canal preparation.
With third generation techniques the cement is mixed in a vacuum and pressurized upon insertion.
10. 1.h. Chordoma. 2. a. Chondrosarcoma. 3. b. Ewing’s sarcoma.
Chordoma is in the spinal column, often sacrococcygeal and manifests as sacral/pelvic/hip pain or even bowel symptoms. Typically, it has physaliferous cells (bubble-like/vacuolated).
Chondrosarcoma is commonly found in the pelvic girdle, and shows a mineralizing pattern due to its cartilage content. Histology often shows large cells with more than one nucleus.
Ewing’s sarcoma should be suspected in the patient younger than 30 years old, particularly with histology showing a‘small round cell tumour’.
11. 1.h. Titanium head. 2. b. Cobalt-chrome acetabular shell with ceramic liner.
3.c. Polyethylene socket.
Bearing surface choices are always controversial. Newer ceramic technologies are very hard wearing but do not have enough long-term survival data to make them comparable with the traditional poly/CoCr combination. The Swedish Hip Registry reports the polyethylene cup as having the lowest revision rate of all combinations over 10 years. Cemented polyethylene cups have a 40% lower revision rate over 10 years than uncemented sockets.
Metal-on-metal, although usually aimed at the younger market, is also very useful in those at high risk of dislocation, e.g. Parkinson’s, due to the large jump distance required to dislocate. Metal-on-metal articulations such as resurfacings are more likely to produce an immune-mediated aseptic lymphocytic vasculitis-associated lesion (ALVAL) response in young women, as well as elevated blood metal ion levels, and are often avoided for this
Chapter 5– Hip and pelvis: Answers
reason. Ceramic components are very hard wearing but also brittle, making their toughness low in comparison. They have been known to fracture, thereby making revision extremely challenging once there is ceramic debris within the joint. They are also known to cause squeaking noises. Stripe wear is localized wear thought to occur either during
reason. Ceramic components are very hard wearing but also brittle, making their toughness low in comparison. They have been known to fracture, thereby making revision extremely challenging once there is ceramic debris within the joint. They are also known to cause squeaking noises. Stripe wear is localized wear thought to occur either during