Femur Quadriceps femoris tendon Anterior cruciate ligament Posterior cruciate ligament Patella Lateral meniscus Medial meniscus Lateral collateral ligament Patella ligament Tibia Medial collateral ligament Fibula Tibia Fig 2. The synovium of the right knee joint: lateral (left) and posterior views. Note that the synovium extends up behind the patella (remember for joint aspiration, p708), and that both cruciate ligaments are extrasynovial (but are intracapsular). NB: the joint capsule is distended in these images by infusion of \202 uid. Fig 3. Tibial plateau and ligaments. Note that on the tibial plateau the attachments in the midline from anterior to posterior are: \200 Tranverse ligament \200 Anterior horn of medial meniscus \200 Anterior cruciate ligament \200 Anterior horn of lateral meniscus \200 Posterior horn of lateral meniscus \200 Posterior horn of medial meniscus \200 P osterior cruciate ligament. Pain in the knee The common symptoms are anterior knee pain or pain and swelling. Anterior knee pain can be due to many causes (see below). Patellofemoral pain syndrome (PFPS) Is com mon in young athletes \200\224espe- cially runners \200\224and may be associated with overu se as well as lower limb malalignment and patella tracking abnormalities. Patella aching is felt after prolonged sitting or on climbing stairs. There may have been a recent increase in sporting activity or trauma \200\224especially history of patella subluxation/dis- locat ion. Eff usion is rare. Medial retropatellar tenderness and pain on patel- lofemoral compre ssion occur: +ve Clarke \200\231s test = pain on patellofemoral com- pression with tensed q uadriceps muscles. There may be either decreased or increased patella mobility. Diagnosis i s clinical. Treat by relative rest \200\224if due to increased training, with structured re habilitation. Quadriceps strengthen- ing exercises are the mainstay of treatment, but many will bene \201 t from hip strengthening exercises as well.76 Reasonable results are also r eported with electrical stimulators.77 NSAIDs may only be eff ective in reducing pain for a few months.78 If symptoms last >1yr, arthroscopic lateral retinacular release may be tried . Shaving the posterior surface of the patella gives uncertain results. Bipartite patella ( \201 gs 1 & 2) is a congenital fragmentation of the patella, found in 1%. This is usuall y an incidental radiographic \201 nding (not to be in- terpreted as a fracture pattern), but may give pain if the superolateral frag- ment is mobile with tenderness over the juncti on. Extra fragment excision may relieve pain.79 Recurrent patella subluxation A tight later al retinaculum causes the patella to sublux laterally, giving medial pain. The knee may giv e way. It is commoner in girls and with valgus knees. It may be familial, or associated wit h joint lax- ity, a high-riding patella (patella alta), or a hypotrophic lateral femoral co ndyle. Signs: Increased lateral patellar movement, accompanied by pain and the re- \202 e x contraction of quadriceps (ie a +ve patellar apprehension test). Contralat- eral instabil ity and young age at time of initial subluxation are risk factors for chronic recurrence.80 Treatments vary (RCTs are needed). If vastus medialis exercises fail to help, lateral reti nacular release with medial soft tissue realign- ment may be of bene \201 t.81 Patellar te ndon transfer is rarely needed.82 Patella tendinopathy (jumper \200\231s knee) is usually i nitiated by micro- or macro patella tendon tears, eg associated with sudden sporting loads. It can occur anywhere in the patellar tendon, and settles with rest NSAIDs. If unable t o rest, steroid injection around (not into) the tendon may help. Eccentric con- traction ex ercises (tension whilst lengthening the muscle) may also help.83 Iliotibial tract syndrome Typically presents with lateral knee pain and ten- derness over lateral femoral epicondyle. Thought to be due to overuse and associated with movement of the iliotibial tract (thicken ed lateral edge of the tensor fascia lata) and the lateral femoral epicondyle. Common in ru nners, it usually settles with sport modi \201 cation, rest, ice, and NSAIDs, but may need ster- oid injection84 and hip adductor strengthening.85 Medial shelf syndrome The synovial fold above the medial meniscus is in- \202 amed. Pain is superomedial. There may be brie f locking of the knee (mimick- ing a torn meniscus). Diagnosis: Arthroscopy. Treatment: Res t, NSAIDs, local steroid injection, or division of the synovial fold arthroscopically. Hoff a \200\231s fat pad syndrome This is impingement of the infrapatella fat pad. Think of it in those with meniscus or ligament-type symptoms when imag- ing shows they are intact. MRI may show a hypertrophic Hoff a pad impinging between articular surfaces (which causes pain under the patella). There may be hydrarthrosis or haemarthrosis (from arteriole rupture). E xtending a bent knee while putting pressure on the patellar tendon margins elicits pain and a defensive behavior.86 688 \200 a m u a r t d n a s c i d e a p o h t r O 689 \200\230All these hags \200\231 Once, after a stay in hospital with a fracture, a patient who was not quite as deaf as she was supposed to be, told one of us (JML) how she had overh eard a newly arrived orthopedic surgeon say to the ward nurse \200\234What are we going to do with all these hags? \200\235. As he progressed down the ward, turning \201 rst to th e left and then to the beds on the right, his mood became morose, then black \200\224as if he was getting angry that all these \200\230hags \200\231 were clogging up his beds, preve nting his scienti \201 c endeavors. But what was really happening, my patient suspected, w as that, as he turned to left and right, he was really nodding goodbye to his humanity, and , dimly aware of this, he was angry to see it go. On this view, these rows of hags were lik e buoys in the night, marking his passage out of our world. We all make this trip. Is there any way back? The process of becoming a doctor takes us away from the very people we \201 rst wanted to serve (Captain Pollard syndrome, p652). Must medicine take the brightest and the best and turn us into quasi-monsters? a m u a r t d n a s c i d e a p o h t r O The answer to these questions came unexpectedly in the months that followed: sheer pressure of work drove this patient \200\231s observations out of my mind. It was winter, and there was \200\231 \202 u. In the unnatural twilight of a snowy day I drifted from bed to bed in a stupor of exhaustion with a deepening sense of a collapse that could not be put off \200 It was all I could do to climb into bed: but when I awoke, I found I had somehow climb ed into a patient \200\231s bed, who had kindly moved over to make space for me, and was no w looking at me with concern in her eyes. Herein lay the answer: the hag must make room for the doctor, and the doctor must make room for the hag: we are all in the same bed. Fig 1. Bipartite patella at the usual position of the superolateral edge. Fig 2. The same image as \201 g 1, but \200\230win- dowed \200\231 to make the lesion mo re obvious (the bean-sized fragment is between 1 and 2 o \200\231clock). This has been one of the major ad- vantages of digitized image viewing. Figs 1 & 2 courtesy of Norfolk and Norwich Uni- versity Hospital (NNUH) Radiology Departmen t. Other causes of anterior knee pain Chrondromalacia patellae, where there is softening of th e articular carti- lage of the patella. Loose bodies Variable symptoms, may have locking, e ff usion, intermittent sudden pain associated with movement. Osgood \200\223Schatter diseas e Adolescent patients with tenderness at tibial tu- bercle (see p704). Prepatella bursitis (housemaid \200\231s knee) Swelling anterior to patella, typically occurs following trauma or overuse (see p690). Knees that swell Arthritis Knee swelling may occur with any ar- thritic process. Primary os teoarthritis (OA) can be de \201 ned as degeneration of the articular cartilage and surfac es of a joint with no predisposing fac- tors \200\224in this sense, the disease is idiopath ic, though current research is suggesting many of these cases have subtle underlying congen ital/developmental defects. In Secondary OA there is an underlying pre- cipitant to the deg enerative process (see MINIBOX). OA is associated with \200\200BMI, genetic factors, age a nd occupation. Patients complain of pain on initiating movement. Stiff ness follows inactiv ity, but often resolves in <30mins. In the knee, OA particularly aff ects the posterior pat ella and the medial compart- ment, so tending to varus deformity. Treatment: NSAIDs, knee s upport (Tubi- grip ), weight loss, local steroid injections, knee replacement (p706), or o ste- otomy (to correct varus deformity). Some may bene \201 t from augmentation of the syn ovial \202 uid within the joint with hyaluronan (see BOX).1 \200\207Remember that a unil aterally swollen knee may be a septic arthritis. Diagnosis is made on the basis of aspirati on, so avoid steroid injections prior to this (p708). \200\207Aspiration of a replaced joi nt must be done under sterile conditions in theater. Meniscal cysts Typical patient: A youn g man, with past trauma, then insidi- ous development of cyst. Pain: Over the joint line. L ateral cysts are 5 \200\22310 \211\210 more common than medial. Swelling may disappear with full \202 exion. The meniscus is often torn radially (an otherwise unusual direction) so there may be knee clicking and giving way. \202\202 : MRI. Treatment: Arthroscopic decomp ression.87 Ligament tears, meniscus lesions, patellar dislocation See p754. Osteochondritis dissecans Subchondral bone becomes avascular, and may progress to fragments of bone and ov erlying cartilage (osteochondral frag- ments) breaking away from the bone to form loose bod ies. Cause: Unknown. Typical site: Lateral side of the medial femoral condyle. Typical pati ent: 13 \200\22321-year-olds.88 Symptoms: Pain after exercise with intermittent knee swell- ing. Locking may occur. Imaging: MRI reveals articular surface defects/loose bodies Treatm ent: Stable lesions are treated conservatively, as spontaneous healing can occur. Unstable fragments may be pinned in place. Loose bodies may be removed and the defect drilled to pro mote \201 brocartilage formation.89 Loose bodies cause knee locking (all movements may be jammed unlike lock- ing from torn menisci when only extension is limited). Also, there is eff usion/ swelling. Diagnosis: Plain \201 lms US (helps show if fragments are intra-a rticu- lar).90 \202\202 \202\202 : Tophi (gout).91 Causes: Osteochondritis dissecans ( \211 3 loose bodies), osteoarthritis ( \211 10 loose bodies), chip fractures of joint surfa ces ( \211 3 loose bod- ies) or synovial chondromatosis (>50 loose bodies). When locking is a problem, loose bodies are best removed \200\224eg arthroscopically. Bursitis 16 bursae surround the knee. Most commonly aff ected are: the pre- patellar bursa ( \200\230housemaid \200\231s knee \200\231) where swelling over the anterior inferior patella is due to in \202 ammation and \202 uid in the bursa due to friction (kneeling); the infrapatellar bur sa ( \200\230clergyman \200\231s knee \200\231 \200\224they kneel more upright); and the se mimembranous bursa in the popliteal fossa (a popliteal cyst which diff ers from the \200 \230Baker \200\231s cyst \200\231 which is a herniation from the joint synovium). Prepa- te llar bursae may be aspirated, have hydrocortisone injected to decrease re- currence. If ver y persistent it may need excision. Pain may be relieved by topi- cal NSAIDs. Aspiration dis tinguishes friction bursitis from suppurative bursitis, which needs drainage and antibiotic s, eg \202 ucloxacillin 250mg/6h PO (adults). 690 \200 Secondary OA causes \200 Post traumatic \200 Post-operative \200 Post-infective \200 Malposition \200 Mechanical instability \200 Osteochondritis dis- secans (below) a m u a r t d n a s c i d e a p o h t r O 1 This technique involves a 5-week course (2mL/wk) of high molecular weight intra-articular hyaluronan derivatives (eg Synvisc ). Any eff usion is drained to dryness. A 5-week cours e may be repeated at 6 months. See BOX OPPOSITE for effi cacy. 691 Results trials and meta-analyzes in knee osteoarthritis NB: knee OA is the commonest joint disease in Europe ( \201 g 1). \200 Women (especially if >55yrs old) are at greater risk .92 \200 Weight loss in women reduces risk of getting OA symptoms.93 n=796 \200 Paracet amol ( tramadol) & quadriceps-strengthening exercises can help.94 \200 Trials comparing NSAIDS are often \202 awed because the drugs compared tend not to be used in comparable doses, as ex- pressed as a fraction of the maximum daily dose.95 16 trials Topical ibuprofe n may be as good as oral in older patients, and has fewer SE.96 \200 There seems to be be ne \201 t from intra- articular steroid injections in the short term, but long-term result s are unclear.97 Some trials report bene \201 ts which only last a week or so.98 N=98 \200 Hyaluronan is a physiological substance found in synovial \202 uid that gives lubri ca- tion and protection to articulating sur- faces. Cochrane meta-analyzes suggest that int ra-articular injection of hyaluro- nan (visco-supplementation) has a role in the therapy of knee osteoarthritis, providing pain relief and improved func- tionality for periods longer than steroid injection. There are a number of avail- able formulations, though analysis li mi- tations meant that no singular one could be recommended above the others.99 76 trials \200 Transcutaneous electrical nerve stimu- lation (TENS) for knee osteoarthritis is a non invasive modality in physiotherapy. Diff erent modes of TENS setting (high rate and strong burst mode) show signi \201 cant bene \201 t in relief of pain and stiff ness over placeb o.100 \200 While exercise is known to have bene \201 cial eff ects in knee osteoarthriti s, improving both functionality and pain, the appropriate intensity level of exercise regim e remains unclear and open to further investigation.101 \200 Knee replacement (p706) is o ften the treatment of choice. However, 21% of patients are still getting knee pain one or m ore years post-op. Signi \201 - cant complications include preventable thromboembolism. In termittent pneumatic compression devices and low molecular weight heparin are sig- ni \201 cantly better than warfarin and aspirin in preventing DVT. Incidence of asymptomatic PE: 1 1.7% for aspirin, 8.2% for warfarin, and 6.3% for pneu- matic compression grOUP. (Numbers o f symptomatic PEs are too small to produce reliable statistics.)102 23 trials \200 Post-o perative aseptic loosening and other problems requiring revision are a problem in 9% over 5 yrs for unicompartmental prostheses (7% over 4yrs for bicompartmental prostheses). Serious infections may be less in those centers doing many procedures.103 a m u a r t d n a s c i d e a p o h t r O Fig 1. Degenerative change of OA in the left knee. Note genu varus deformity, and how the m edial com- partment is most aff ected. Courtesy of Norfolk & Norwich Univer- sity Hospital (NNUH) Radiology Dept. A journey on foot Ankle and foot examination 25 of extension (dorsi \202 exion) and 30 of \202 exion (plantar \202 exion) are the norm at the tibiotalar joint. Inversion and eversion are from the subtalar and midtarsal joints. Toes should have between 60 and 90 extension. Note any callosities. Examine the arches ( \201 g 1). Watch as the toes are li fted off the ground, and on standing on tiptoe. Examine gait and shoes (normal wear pattern is medially under ball of foot, posterolaterally at heel). Hallux valgus The big toe devia tes laterally at the metatarsophalangeal joint ( \201 g 2). Associated with genetic predis oposition, female gender, age, type of footwear and BMI. Pressure of the metatarsophalangea l joint against the shoe leads to bunion formation. Secondary arthritis in the joint is com mon. Bunion pads and plastic wedges between great and second toes may relieve pain, but sev ere deformity requires surgery. Many diff erent operations are used. Gener- ally, the defor mity is corrected with a metatarsal osteotomy \200\224up to \205\223 are un- satis \201 e d with the result.104 End-stage MTP joint OA (Hallux rigidus) is treated with arthrodesis ( joint fusion). Pes planus ( \202 at feet) The medial longitudinal arch ( \201 g 1) collap ses \200\224leading to the whole sole (or near to it) coming in contact with the ground. Fl at feet are normal when a child is learning to walk. The medial arch develops over the next few years. In adults \202 at feet are associated with dysfunction of the posterior tibia lis tendon (PPT) (a dynamic stabilizer of the medial arch). In most, it is asymptomatic and may not need intervention if the arch restores itself on standing on tiptoe (ie a \200 \230mobile \200\231 \202 at foot). Pain may develop medially over the PPT and there may b e progressive forefoot abduction and hindfoot valgus deform- ity with loss of ability to he el rise, as the condition progresses. Weight loss, supportive shoes (with insoles), orthosi s may help in mild cases.105 Prevention: studies of feet in India show that going barefoot until 6 years old keeps feet healthy. Pain and limitations in sport tend to be post-op comp lications (eg after the Viladot procedure), so don \200\231t advise surgery lightly.106 Pes cavus Accentuated longitudinal foot arches which do not \202 atten with weight-bearing. May be idiopathic, or associated with an underlying neurological condition (see MINIBOX). C law toes may occur, as weight is taken on metatarsal heads when walking (hence causing pain ). Other symptoms: Diffi culty with shoes; foot fatigue; mobility \200\201; ankle instabili ty/sprains; callosities. If foot used to be normal, refer to a neurologist. MRI may help es tablish any underlying disease. If orthoses and custom foot- wear fail, surgical procedures include (if vascular supply is good) soft-tissue releases, tendon transfers, arthrodesis.1 07 Lesser toe deformities 1 Hammer toes: These are extended at the MTP joint, hyper \202 e xed at the PIP joint and extended at the DIP joint. Second toes are most commonly af- fecte d. 692 a m u a r t d n a s c i d e a p o h t r O Fig 1. The medial (1) and lateral (2) longitudinal arches of the foot. Pes cavus associations \200 Spina bi \201 da \200 Cerebral palsy \200 Polio \200 M uscular dystrophy \200 Charcot \200\223Marie \200\223Tooth dis. \200 Syringomyelia \200 Friedreich \200\231s ataxia \200 Spinal tumor 2 Claw toes: Extended at the MTP joint but \202 exed at both PIP and DIP joints. The oper ative treatment for both hammer and claw toes is metatarsal shortening ( \202 exible defor mity) or PIP joint arthrodesis ( \201 xed deformity). 3 Mallet toes: Flexion deformity of the DIP joint in isolation treated with \202 exor tenotomy ( \202 exible deformity) or DIP joint arthrodesis ( \201 xed deformity). 693 Classi \201 cation of severity of hallux valgus deformity Hallux valgus angle (HVA) <15 15 \200\22320 20 \200\22340 >40 Intermetatarsal angle (IMA) <9 9 \200\22311 11 \200\22318 >18 Normal Mild Moderate Severe a m u a r t d n a s c i d e a p o h t r O NB: sources vary in de \201 nitions. Surgery may be problematic. Mild and moderate deformi ties may be correct- ed with a distal metatarsal osteotomy (eg Mitchell \200\231s or Chevro n osteotomy). Severe deformities also require correction of the intermetatarsal angle (eg S carf osteotomy).104,108 Fig 2. Weightbearing AP image show- ing a hallux valgus deformity and the hallux valgus ang le (HVA) and inter- metatarsal angle (IMA). Courtesy of Professor Peter Scally. Footnotes in History By the time we get down to the foot, our anatomical interest is \202 agging, but on close inspection \200\230we would never have believed, my dear Jos , that so much glory could \201 t into a shoe \200\231.Gabriel Garc a Marquez 1989 Feet made for The Ge neral in His Labyrinth walking are really quite old \200\224some 4 \200\2237 million years, according to Sterkfon- tein Man \200\231s remains.1 The signi \201 cant thing about these old feet is that they can and did take us anywhere. We started off swinging from tree to t ree in an African forest, and began quite a journey on foot that has taken us not only to t he furthest reaches of our own world, but also to another \200\224with some extra help. And how long will those historical footprints last on the moon? Perhaps another few million ye ars.109 The painful foot \200\207Look at a wet footprint and wear on the shoe sole to assess funct ional anat- omy of the loaded foot. Many of the conditions mentioned in \200\230the foot \200\231 (p692) can be painful. Other causes of pain are mentioned here. Young children rar ely complain of foot pain: if in the sole think of a foreign body. Shoe pressure on a promi nent navicular bone, or sometimes an acces- sory bone, or a prominent posterosuperior os ca lcis may need surgical trim- ming. Osteochondritis (p702) of foot bones may be the cause (d o radiography). Metatarsus primus varus 1st metatarsal midline angulation. Typical patients : teenagers. It may be familial. If deformity is great, a metatarsal or wedge osteotomy may be tried.110 Tarsal bone coalitions can also cause pain. Ingrowing toenails Typically the big toe. Incorrect nail cutting pressure of shoes predispose to the lateral nail digging into its \202 eshy bed, which reacts by becoming heaped up infection-prone \200\230prou d \202 esh \200\231. Conservative treatment in- volves tucking cotton-wool soaked in surgi cal spirit under the proud \202 esh and awaiting nail growth (then cut it straight with ed ges protruding beyond \202 esh margins). Antibiotics may help the young.111 Recurrent inf ections may need surgery. Nail avulsion plus chemical matrixectomy (with phenol or sodium b i- carbonate) to the nail bed is better than simple avulsion112 (but there may be more post -op infection.113 Adult forefoot pain (metatarsalgia) Increased pressure on the metatarsal heads causes pain. Treatment: insole supports, surgery other than for rheuma- toid arthriti s is unpredictable. Other causes include synovitis, sesamoid frac- ture, and traumatic inju ry. Morton \200\231s metatarsalgia Pain is from pressure on an interdigital neuroma be- twe en the metatarsals (eg from fashion shoes). Pain usually radiates to the lateral side of on e toe, and the medial side of its neighbor (eg toes 3 & 4). A compression test of the aff e cted web space is quite speci \201 c. MRI helps, and ultrasound if by an experienced worke r.114 Neuroma excision may be needed.115 March (stress) fractures occur in the shaft of the 2nd or 3rd metatarsals and may follow excess walking. Radiographs may be normal, or have s ubtle periosteal changes: the history should raise suspicion and prompt a scour- ing search of the metatarsi. Radionuclide bone scans are more discriminat- ing. Treatment is rest and analgesia. If pain is severe, try a plaster cast while awaiting healing. Pain in the heel Causes: ( \200 means may respond to steroid injection) \200 Diseases of the calcaneum \200 Rupture of calcaneal tendon (p712) \200 Postcalcaneal bursitis (back of heel) \200 Plantar fasciitis \200 1 \200 Lymphoma (in children) MRI may have a role in undiagnos ed heel pain (eg from occult stress frac- tures).116 Apart from calcaneal diseases and tend on rupture, conservative treatment (eg shoe alteration to prevent rubbing) may help. If not , with post- calcaneal bursitis the bursa may be surgically removed. Corns Focal friction-d ependent hyperkeratotic intradermal nodules develop bony pressure points (eg the top of ham mer toes, \201 g 1), which stop keratinized skin cells coming to the surface. A bursa-lik e structure may form around these islands. Likelihood \200\200 if neuropathy eg diabetes. U nlike calluses they have a core of keratin, occur only on the foot, and cause pain.117 Mana gement: Optimize footwear (not too tight or loose, an instep); chiropody ( softening w ith sali- cylic acid) or excise the corn (try to remove its core without causing bleeding). More radically, remove the culprit bone too (eg hammer toe condylectomy).118 694 a m u a r t d n a s c i d e a p o h t r O Arthritis of the subtalar joint \200 Calcaneal paratendinopathy \200 \200 Tender heel pad \200 \200 Infection. 1 If proximal planar fasciitis doesn \200\231t respond to injections, extracorporeal shockw ave therapy is a rea- sonable alternative to surgery.119 695 a m u a r t d n a s c i d e a p o h t r O Fig 1. Pressure points in a foot with hammer toe. Talus and Talos \200\224a better grasp of what we are looking at It can be diffi cult to id entify and orientate a bone (or indeed any anatomical structure) in isolation \200\224a \202 ashback for some to an old-style anatomy viva. Building up a picture of what you are l ooking at using context can make the task easier. This context can be provided by a number of means, for example by using a combination of imaging, anatomy prosection and dissection, and functional techniques. The aim is to bring anatomy to life in our own minds as close to that which we see in our p atients before us, almost as if constructing a mental anima- tion. In the 1963 \201 lm, J ason & the Ar- gonauts, Ray Harryhausen famously animated articulated skeleton war- riors ( grown from the teeth of the Hydra by King Ae tes of Colchis) in a feat of which most stude nts of anatomy would be jealous. In the same \201 lm, Harryhausen also ani- mated the bro nze automaton Talos (not to be confused with the talus, \201 g 2), forged by Hephaestus a s a gift from Zeus to Europa, queen of Crete. Although there are many permuta- tions to cla ssical myth, in the \201 lm version Jason slays Talos by dislodg- ing a bolt in his heel that caused ex- sanguination of the ichor from the single vein that ran from his neck to hi s heel \200\224perhaps re \202 ective of the understanding of anatomy and physiology in th ose ancient times. Fig 2. The talus bone of the foot \200\224not easy to identify or orientate in isolation. W hich is view is which?1 So, although every student will have their own methods of learning anat- omy, the process o f study may be helped by thinking of animation \200\224or even \200\230anatimation \200 \231 \200\224and not just the stationary. Technology has come a long way from 1963, with th e development of excellent aids, tools and resources that can enhance the learning of anato my, eg at www.anatomy.tv and www.e-anatomy.org. 1 Top left = inferior view; top right = lateral view; bottom left = medial view; bottom rig ht = superior view. Osteomyelitis This is an infection of bone. Its incidence reduces as living standards rise. It can be categorized as acute haematogenous, secondary to contiguous local in- fection (w ith or without the presence of vascular disease), or vertebral (see below). All forms can p rogress to chronic osteomyelitis.120 Infection may spread from boils, abscesses, pneumonia, or genito- urinary instrumentation, though often no primary site is found. Clinical featur es See BOX, opposite. Tests ESR/CRP \200\200, WCC \200\200. Blood culture (+ve in 60%). Bon e biopsy and culture is gold standard \200\224but rarely required for acute osteomyelitis. Swabs from discharging sinuses may give misleading results.126 Radiographic changes are not apparent for 10 \200\22314 days but then show haziness loss of density of af- fected bo ne, then subperiosteal reaction, and later, sequestrum and involu- crum (see BOX, OPPOSITE & \201 gs 1 \200\2233). NB: infected cancellous bone shows less change. MRI is sensitive and speci \201 c (88% and 93%, vs 61% and 33% for isotope scans) \200\224and avoids ionizi ng radiation, but isotope scans are still sometimes required (eg in presence of prostheses causing imaging artifact).127 Treatment Drain abscesses and remove sequestra by open surger y. Culture all sequestra. Antibiotic: vancomycin 1g/12h and cefotaxime 1g/12h IVI un- til t he organism and its sensitivities are known. Continue for 6 weeks. Alternative treatments f or adults are fusidic acid or clindamycin. Cipro \202 oxa- cin 500mg/8 \200\22312h PO is s uitable for Pseudomonas osteomyelitis, but be guided by sensitivities and a microbiologist. In children, prevalence of Haemophilus in \202 uenzae osteomyelitis is reducing due to th e HIB vaccination.128 Chronic osteomyelitis Poor treatment results in pain, fever, and sinu s sup- puration with long remissions. Radiographs show thick irregular bone. Treat- ment in volves radical excision of sequestra (infected dead bone), skeletal sta- bilization, \200 \230dead-space \200\231 management (often needs plastic surgical input) and antibiotics (as above, modi \201 ed according to sensitivities) for \211 12 weeks. Com- plications: Amyl oid, squamous carcinoma development in sinus track. Bone TB (eg vertebral body = Pott \200 \231s disease).129 This represents 1 \200\2233% of all TB; incidence is rising, rare in UK. Spread is haematogenous or via nearby nodes. Signs: Local pain, swelling, and \200\230col d abscess \200\231 formation joint eff usion are common. With joint involvement there is pain, swelling, pain on movement and muscle wasting. Also: weight \200\201; malaise; fever ; lethargy. Differential diag- noses: Malignancy; other infections; gout; rheumatoid. Imagi ng: Radiographic changes: bone rarefaction (=reduction in density/solidity), periostitis ch anges, cyst formation. Later there is loss of joint space, erosions and bony ankylo- sis. A lso look for soft tissue swellings (abscess; tenosynovitis/bursitis). MRI is especially use ful in analyzing soft tissue changes. Bone scans may be useful in diagnosing dactylitis (a feature of childhood TB). One recent meta-analysis showed PET to be superior to all other f orms of imaging, with a sensitivity of 96% and a speci \201 city of 91%.130 Other tests: A spirated pus is creamy and may be positive on culture or ZN stain; ESR \200\200; Mantoux +v e; CXR; HIV tests. Treatment: Drain abscesses, immobilize aff ected large joints. Standard 6-month courses (OHCM p386) of eg isoniazid (300mg/day), rifampicin (600mg/day) and pyrazi- namide (1.5g/day) may not be long enough. Late arthroplasty or arthrodesis is needed for g ross joint destruction.131 696 \200 Common organisms \200 Staphylococcus aureus Pseudomonas \200 E. coli \200 Streptococci Other organisms \200 Salmonella (esp. with sickle cell disease)121 \200 Brucella122 \200 Proteus/Klebsiella123,124 \200 Mycobac teria \200 Fungi125 a m u a r t d n a s c i d e a p o h t r O Complications \200 Septic arthritis \200 Fractures \200 Deformity \200 Chronic oste omyelitis 697 Clinical features of osteomyelitis Patterns of infection Cancellous bone is typically aff e cted in adults \200\224commonly in vertebrae (IV drug use) and feet (diabetics); in childre n, vascular bone is most aff ected (eg in long-bone metaphyses \200\224esp. distal femur, u pper tibia). Infection leads to cortex erosion, with holes (cloacae). Exudation of pus lift s up the periosteum interrupting blood supply to underly- ing bone and necrotic fragments o f bone may form (sequestrum). The presence of sequestra is typical of chronic infection. Ne w bone formation created by the elevated periosteum forms an involucrum. Pus may discharge into joint spaces or via sinuses to the skin. The patient Pain of gradual onset over the co urse of a few days \200\224with ten- derness, warmth, and erythema at the aff ected part; u nwillingness to move; slight eff usion in neighboring joints; signs of systemic infection. All signs are less marked in adults. Risk factors \200 Diabetes \200 Vascular disease \200 Impaired immunity \200 Sickle cell disease \200 Surgical prostheses \200 Open fractures \200 Impaired immunity a m u a r t d n a s c i d e a p o h t r O Fig 2. Axial T1-weighted MRI of the foot through the metatarsals, showing reduced signal wi thin the \201 rst metatarsal (from replacement of the marrow fat with pus) consistent wit h osteomyelitis. Fig 1. Osteomyelitis causing destruction of the 5th metatarsal head and the base of the 5th proximal phalanx. Note also the vascular calci \201 cation in this patient, who had diabe tes. Fig 3. Axial T1-weighted MRI of the same patient as \201 g 2, this time with FAT SAT (fat saturation) and IV gadolinium contrast. The eff ect of this technique is to suppress the m arrow fat and enhance the infection. Images courtesy of Norfolk and Norwich Uni- versity Hospital (NNUH) Radiology Department. Bone tumors: malignant Tumors present with pain, swelling or pathological fracture. Bone is a common site for secondaries (eg from breast, bronchus, prostate, kidney). Primary bone n eoplasia is rare: incidence of 9 per million population/ year.132 Delays in diagnosis are c ommon. Metastases are blood-borne and usually arise in the lungs or other bones. Staging is done with MRI or combination techniques such as PET-CT.133 Treatment of these rare and hig hly aggressive primary tumors is best carried out in multidisciplinary specialist treatment centers. Osteosarcoma is the most common malignant primary bone tumor.1 Pri- mary osteosar coma typically aff ects adolescents and arises in the metaphyses of long bone, especially a round the knee. Secondary osteosarcoma may arise in bone aff ected by Paget \200\231s disea se or after irradiation. Radiography: Bone destruction and new bone formation, often with m arked periosteal elevation (sunray spiculation and Codman \200\231s triangle, respectively) . Treatment: Resection + chemotherapy, eg doxorubicin, cisplatin and methotrexate.134 A cur e rate of 60 \200\22370% is achievable.134 Giant cell tumor Rare tumor \200\224characteriz ed by multinucleated giant (osteoclast like) cells \200\224hence also called osteoclastoma. This histologically \200\230benign \200\231, primary skeletal neoplasm, with unpredictabl e biological aggressive- ness, is commonest in 20 \200\22344-yr-olds.135 It occurs around e piphyses (esp. knee). The tumor is osteolytic and often slowly progressive, sometimes resul ting in pathological fracture. Treatment is by detailed and thorough curettage result- ing in 75% cure. Recurrences are usually treated by wide excision. Ewing \200\231s sarcoma This malignant round-cell tumor of long bones (typically diaphysis) and limb girdles, usually p resents in adolescents. Radiographs show bone destruction, concentric layers of new bone fo rmation ( \200\230onion-ring \200\231 sign) and a soft tissue mass. MRI is helpful. Typical ly those with Ewing \200\231s sarcoma have a t11 : 22 chromosomal translocation. Treatment: Chemotherapy, surgery and radiotherapy are required. The key adverse prognostic factor is metasta- ses at diagnosis (5-year recurrence-free survival is 22% \200\224vs 55% if no meta s- tases at diagnosis).136 n=975 Chondrosarcoma may arise de novo or from malignant transfo rmation of chondromas. It is usually associated with pain or a lump and presents in the axi al skeleton of the middle-aged. \200\230Popcorn calci \201 cation \200\231 is typical on radiog- raphy. MRI/CT will better de \201 ne tumor extent. Treatment: It doesn \200\231t r espond to chemotherapy or radiotherapy, so treatment is by excision. Inadequate surgery is accompanied by local recurrence, often of a higher grade of ma- lignancy. The cure rate dep ends on the type and grade of chondrosarcoma at diagnosis. Malignant \201 brous histiocyt oma is the rarest primary bone tumor. It arises in middle age, often at the site of a previ ous bone abnormality (eg bone in- farcts). Treatment is as for osteosarcoma. Chordomas aris e from notochord remnants in the spine and are typically sa- cral, and quite big before a d iagnosis is made. Bladder & bowel sphincter prob- lems may occur. Radical surgery + pre-op radiotherapy cure <20%. The others may have a slow and diffi cult death.137 Surgical recons truction (after excising a bone tumor) may involve replac- ing aff ected bone with a metal and polyethylene endoprosthesis \200\224as an alter- native to amputation. Excellent and du rable reconstruction is possible using massive endoprostheses or bone allografts. 85% of pa tients now have limb salvage following chemotherapy for primary bone tumors. 698 \200 Radiological features \200 Bone destruction \200 New bone formation \200 Soft tissue swelling \200 Periosteal elevation a m u a r t d n a s c i d e a p o h t r O 1 There are many diff erent subtypes, including intramedullary, periosteal, parosteal & tel angiectatic. 699 Bone tumors: benign Osteochondroma is the commonest benign bone tumor, usually occurring ab out the knee, proximal femur, or proximal humerus. Presents as a painful mass associated wi th trauma. Seen on x-ray as a bony spur arising from the cortex and usually pointing away f rom the joint.Treatment: Remove if causing symptoms, eg pressure on adjacent structures. An y osteochondroma continu- ing to grow after skeletal maturity must be removed because of ri sk of malig- nancy (arises rarely in solitary osteochondromas but in up to 10% of patients with hereditary multiple exostoses \200\224an autosomal dominant inherited condi- tion). Os teoid osteoma is a painful benign bone lesion that occurs most commonly in long bones of ma les 10 \200\22325yrs old (and also often in the spine). It appears as local cortical sclero sis on radiographs with a central radiolucent nidus. Within the nidus there may be a small nucleus of calci \201 cation The nidus produces prostaglandins leading to pain unrelated t o activity, and relieved by aspirin (and other prostaglandin inhibitors) Treatment: CT guid ed biopsy and radio- frequency ablation.138 NB: in young adults, any bone pain responding t o aspirin within 15min could be caused by an osteoid osteoma. Plain radiographs may miss th ese tumors. CT is the best imaging modality.139 Chondroma These benign cartilaginous tumors may arise from bone sur- faces or within the medulla (=enchondromata). They may cause loca l swelling or fracture. Treatment is rarely needed, except to exclude malignancy (chon- dro sarcoma \200\224see OPPOSITE). NB: Carney \200\231s syndrome is gastric leiomyosarcoma, plu s pulmonary chondroma plus a non-adrenal paraganglioma.140 Fibrous dysplasia of bone is a d evelopmental abnormality where bone is not properly formed. May lead to pain and increased risk of fracture. Surgical stabilization is sometimes needed. In the polyostotic form bisph osphonates may help relieve symptoms. a m u a r t d n a s c i d e a p o h t r O