Vikas Khanduja, MSc, FRCS (Orth)

Consultant Orthopaedic

Surgeon,

Addenbrooke’s -

Cambridge University

Hospital NHS Trust,

Cambridge

CB2 0QQ, UK.

Associate Editor, the

Journal of Bone and

Joint Surgery [Br]

email: vk279@cam.ac.uk

Contributors:

Simranjeev Johal

SpR East of England

Rotation

Karanjeev Johal

SpR, North Thames

Rotation

Exam Corner November 2012 - Answers

Vivas Adult Pathology

A 54-year-old woman who underwent a mastectomy for breast cancer 12 months ago followed by adjuvant chemotherapy presents with a two week history of increasing mid-thoracic back pain. Over the last two days her legs have felt weak and she has struggled to walk. There is no history of urinary or faecal incontinence. She is otherwise fit and well.

This is the MRI of her spine (Fig. 1).

1. Describe the image. Answer: This is a T2-weighed sagittal MRI of the thoracic spine. There are multiple lesions in the vertebral bodies with vertebral collapse of T4 and encroachment of the cord at T6 representing spinal cord compression. There is also an increase in the thoracic kyphosis.

2. What is the likely diagnosis and how would you manage this patient in the A&E department? Answer: The likely diagnosis is metastatic vertebral lesions from breast cancer, now causing spinal cord compression. I would take a full history and examination, especially neurological examination. Analgesia would be offered and unless contraindicated a loading dose of at least 16 mg of dexamethasone would be given as soon as possible after assessment. This would be followed by a short course of 16 mg dexamethasone daily while treatment is being planned. I would also consider immobilisation of the spine if unstable and an urgent referral to the oncologists and the spinal surgeons.

3. What are the options for definitive management? Answer: Management is guided by NICE guidelines. Conservative management will include radiotherapy and this maybe suitable for those requiring definitive treatment or who are unsuitable for surgery. If surgery is appropriate in patients with (metastatic spinal cord compression) MSCC, attempt to achieve both spinal cord decompression and durable spinal column

1. Which one of the following statements is false with regards to the use of autotransfusion in orthopaedic surgery? Answer: e. Is a good source of clotting factorsAutotransfusion is not a good source of clotting factors (as they become depleted) and it is commonly employed when cement is used.

2. What is the probable mechanism of failure of a cemented total hip replacement with radiolucent lines on the anteroposterior radiograph in Gruen zones two and six? Answer: a. Medial stem pivotWith a lack of superomedial and inferolateral cement support the prosthesis pivots around the medial stem eventually causing cement fracture in Gruen zones 2 and 6.

3. Regarding genetic transmission, which one of the following inheritance patterns is seen in patients with familial hypophosphataemic rickets? Answer: d. X-linked dominant

4. Delayed gadolinium-enhanced MR imaging to detect articular cartilage degeneration relies on

the content and depletion of which one of the following in the hyaline cartilage? Answer: a. Proteoglycan Gadolinium allows accurate assessment of the amount of proteoglycan in the articular cartilage.1

5. During the process of nerve regeneration, which one of the following modalities is the first to return? Answer: d. Pain Recovery of deep cutaneous sensibility (pain caused by deep pressure) is the first sign of nerve recovery.

6. A 25-year-old weight-lifter had an MRI examination of his shoulder, which shows a SLAP lesion with a cyst in the spinoglenoid notch. Which one of the following clinical signs/tests would be expected to be positive in this scenario? Answer: e. SpeedSpeeds test is undertaken with the elbow extended, forearm supinated and humerus elevated to 60° – positive for long head of biceps pathology and SLAP tears.

MCQs – Adult Pathology – Single Best Answer

Fig. 1

stability. Consider vertebral body reinforcement with cement for patients with MSCC and vertebral body involvement who are suitable for instrumented decompression but are expected to survive for less than one year. Consider vertebral body reconstruction with anterior bone graft for patients with MSCC and vertebral body involvement who are suitable for instrumented decompression, are expected to survive for one year or longer and who are fit to undergo a more prolonged procedure.

Surgery more likely

Radiotherapy more likely

Prognosis > 3 months < 3 months

Tumour burden Low High

Spine stability Unstable spine Stable

Diagnosis New primary Established disease

Levels of compression One Several

Performance Status Good Poor

Time since onset of neurology

< 48 hours > 48 hours

4. What factors govern the decision making process? Answer: As mentioned above a number of factors influence decision-making including fitness for surgery and life expectancy. Surgical factors may include degree of kyphosis, surrounding bone quality and associated neurology. Vertebroplasty or kyphoplasty can be considered for vertebral metastases with no evidence of MSCC or spinal instability.2

Trauma

A 42-year-old woman presented with a fall onto her dominant right hand with a painful and stiff elbow. These are her radiographs (Figs 2a and 2b).

1. Describe the radiographs. Answer: Anteroposterior and lateral radiographs of the elbow showing a fracture of the capitellum.

2. What is the pattern of injury in these fractures? Answer: This is normally a coronal shear injury that occurs following a fall onto outstretched hand or elbow.

3. Which gender is this injury most commonly seen in and why? Answer: This injury is more common in females due to the greater carrying angle of the elbow, and also the ability to hyperextend the elbow allowing the radial head to forcefully shear off the capitellum.

4. How would you classify this injury? Answer: Type I - Hahn-Steinthal fracture- Fracture of capitellum in coronal plane- Large osseous fragment The other main type is Kocher-Lorenz (Type II) which is a sleeve fracture of the articular surface with little osseous bone.Broberg and Morrey (Type III) – comminuted fractureMcKee modification also mentions Type IV – coronal shear including capitellum and trochlea.

5. How would you treat it and what approach will you use? Answer: This is a displaced fracture and would cause a block to flexion, I would treat this injury operatively. I would employ a Kocher’s lateral approach to the elbow, starting over the lateral supracondylar ridge, 5 cm proximal to the elbow joint and then continuing distally to the lateral surface of the proximal forearm posterior to the radial head. I would keep the forearm in pronation to avoid injury to the posterior interosseous nerve during the approach. The interval between ECU and anconeus is dissected and a capsulotomy is made. After reduction of the fracture I would use headless screws to fix the fracture and prevent impingement at the radiocapitellar joint.

6. What are the complications?Answer: Nonunion – 1% to 11% with open reduction and internal fixation, heterotrophic ossification (4%) and avascular necrosis.

Hands

This is the clinical photograph (Fig. 3) of a 28-year-old who presented to the hand clinic with a long-standing history of a problem with his thumb.

1. Describe the clinical photograph. Answer: Clinical photograph of Macrodystrophia lipomatosa (ML) which is a rare cause of congenital macrodactyly, associated with progressive proliferation of all mesenchymal elements, but primarily the fibroadipose tissue.3

Unusually it may involve the whole upper limb and abdominal wall involvement has been reported.4 Clinically the condition may present as early as the neonatal period to late adulthood. There is a

Fig. 2a

Fig. 2bFig. 3

male preponderance and usually a single sclerotome appears to be involved. Commonly the lateral aspect of the upper limb along the median nerve distribution appears to be involved while the medial aspect of the lower limb (i.e. along the plantar nerve distribution) is can be affected. The lower limb is more often involved than the upper limb and the 2nd and 3rd digits are more commonly affected. Growth usually stops with the onset of puberty.

2. What is the differential diagnosis? Answer: There are certain conditions, which can present with localized limb hypertrophy. The differential diagnosis of ML includes neurofibromatosis type 1 (plexiform neurofibroma), fibrolipomatous hamartoma (FLH), lymphangiomatosis, hemangiomatosis and Klippel-Trenaunay-Weber syndrome, Mafucci syndrome, Ollier disease and Proteus syndrome. It is important to note that in all these conditions there is a positive family history and these conditions are characterized by cutaneous or systemic manifestations. Fibrolipomatous hamartoma (FLH) is a condition in which digital overgrowth occurs like ML. It usually presents as an isolated nerve lesion and associated with intramuscular fat deposition. But in ML, in addition to deposition of fat in nerve sheaths, subcutaneous and muscle compartment, there is periosteal involvement leading to the bony changes including exostosis, fatty invasion of the medullary cavity, hypertrophy and ankylosis.5,6

3. What is the most likely diagnosis? Answer: Macrodactyly

4. What is the pathophysiology of this condition? Answer: Several theories exist as to the cause of macrodatyly including abnormal nerve and vascular supply to the digits although none have been proven. Macrodactyly may be associated with neurofibromatosis, tuberous sclerosis and Maffuci syndrome.

5. What is the treatment of this condition? Answer: The usual presentation is with problems associated with cosmesis. However patients may present with secondary osteoarthritis or compression of neurovascular structures resulting in entrapment syndromes.7-9 Surgical usually takes the form of a debulking procedure and is dependent on the patient’s symptoms, age, and extent and severity of the disease. A conservative approach is advocated as growth usually stops at puberty also the incidence of nerve injury following extensive debulking or lesion removal is approximately 30% to 50%. A high recurrence rate of 33% to 60% has been reported. In a localised forms of the disease ray amputations have been described.

Paediatrics

Figures 4a and 4b show the initial and post-operative radiographs of a ten-year-old boy who injured his knee in a road traffic accident. Figure 4c is a current radiograph, two years later.

1. Describe the original injury, the current radiological features and how you would manage the case. Answer: The radiograph shows a Salter-Harris Type II injury of the lower femur, which, with its location and mechanism, has a high risk of growth plate arrest.Figure 1c shows a posterior growth plate arrest and corresponding angular deformity. This is likely to progress and, along with the angulation, leave a limb length discrepancy in the order of 5 cm to 6 cm.MRI would be useful in defining the extent of the growth plate tether. However, an attempt to resect any tether would be technically difficult and the results unreliableThe best option would be to ablate the remaining growth plate and correct the angulation and shortening using a circular frame.If such facilities were not available or the child was unsuitable for the method, the angulation could be corrected by supracondylar osteotomy and epiphysiodesis of the contralateral knee.

This 14-year-old boy, previously normal, presented with a painless prominence of his right scapula following a canoeing holiday (Fig. 5).

2. What is the condition, what are the differential diagnoses and, of these, which is the most likely in this case?Answer: The diagnosis is winged scapula.The aetiology may be in bone (e.g. congenital malformation or subscapular exostosis), joint (e.g. post-inflammatory or traumatic fusion), nerve (neuropraxia of the long thoracic nerve) or muscle.In this case, although the history suggested a nerve injury, the diagnosis proved to be Facio-Scapular-Humeral (F-S-H) Dystrophy. With hindsight, there was already early winging of the left scapula.

Fig. 4a Fig. 4b

Fig. 4c

Fig. 5

Basic Science

A 64-year-old male who has had a total knee replacement a year ago presents with a history of pain and swelling with some discharge from his knee (Fig. 6).

1. Describe the clinical photograph. Answer: There is a sinus in the central portion of midline scar over the knee. There appears to be a significant joint effusion.

2. What is the differential diagnosis? Answer: Infection, either superficial or deep. Chronic discharging sinus.

3. What investigations would you like to arrange? Answer: Blood tests – WCC, CRP and ESR. Microbiological assessment of discharged fluid. Plain radiographs to assess components for loosening.

4. How would you manage this patient? Answer: I would have a high clinical suspicion for infection. I would like to aspirate fluid and undertake a synovial biopsy from the knee to confirm the suspicion. This should be done under sterile conditions in the operating theatre. Combined aspiration and biopsy confirms infection in 90% of cases. Ideal treatment then involves a two-stage surgical procedure with extensive debridement and washout, followed by antibiotics. An articulating/non-articulating cement spacer (with antibiotics) is used prior to implantation of the revision prosthesis. The timing of this is guided by inflammatory markers. The use of a single-stage revision is gaining popularity has been advocated in certain patients where the causative organism is known, no sinuses are present, the patient is not immunocompromised, and

there is no radiological evidence of component loosening or osteitis.11

5. What do you understand by the term biofilm? Answer: Biofilm is a complex aggregation of microorganisms in which cells adhere to each other on a solid substrate.

6. Describe the constituents of a biofilm and the stages in its formation. Answer: Constituents of biofilm include the complex association of microorganisms and a matrix of extracellular polymeric substance (EPS) which is produced by the microorganisms themselves. This EPS is a polymeric conglomeration of extracellular DNA, proteins and polysaccharides. There are five stages in biofilm formation;1. Initial attachment2. Irreversible attachment3. Initial maturation4. Further maturation 5. Dispersion

7. Why are antibiotics ineffective in the presence of a biofilm? Answer: Biofilm cannot be treated by antibiotics as the dense extracellular matrix and outer layer of cells protect the interior microorganisms. This acts as a penetration barrier and in some cases antibiotic resistance can be increased a thousandfold.12

References1. Gray ML, Burstein D, Kim YJ, Maroudas A. 2007 Elizabeth Winston Lanier Award Winner. Magnetic resonance imaging of cartilage glycosaminoglycan: basic principles, imaging technique, and clinical applications. J Orthop Res 2008;26:281-91.2. No authors listed. NHS National Institution for Health and Clinical Excellence. Metastatic spinal cord compression: diagnosis and management of adults at risk of and with metastatic spinal cord compression, CG75, 2008. http://www.nice.org.uk/CG75 (date last accessed 5 March).3. Krengel S, Fustes-Morales A, Carrasco D, et al. Report of eight cases and review of literature. Pediatr Dermat 2000;17:270–6.4. Aydos SE, Fitoz S, Bökesoy I. Macrodystrophia lipomatosa of the feet and subcutaneous lipomas. Am J Med Genet A 2003;119:63-5.5. Jain R, Sawhney S, Berry M. CT diagnosis of macrodystrophia lipomatosa: a case report. Acta Radiol 1992;33:554-5.6. D’Costa H, Hunter JD, O’Sullivan G, et al. Magnetic resonance imaging in macromeliaandmacrodactyly. Br J Radiol 1996;69:502-7.7. Oztürk A, Baktiroğlu L, Oztürk E, Yazgan P. Macrodystrophia lipomatosa: a case report. Acta Orthop Traumatol Turc 2004;38:220-3 (in Turkish). 8. Watt AJ, Chung KC. Macrodystrophia lipomatosa: a reconstructive approach to gigantism of the foot. J Foot Ankle Surg 2004;43:51-5.9. Brodwater BK, Major NM, Goldner RD, Layfield LJ. Macrodystrophia lipomatosa with associated fibrolipomatous hamartoma of the median nerve. Pediatr Surg Int 2000;16:216-18.10. Tuzuner T, Parlak AH, Kavak A, Alper M. A neglected case of macrodystrophia lipomatosa of the foot in an elderly man. J Am Podiatr Med Assoc 2005;95:486-90.11. Vanhegan IS, Morgan-Jones R, Barrett DS, Haddad FS. Developing a strategy to treat established infection in total knee replacement: a review of the latest evidence and clinical practice. J Bone Joint Surg [Br] 2012;94:875-81.12. Stewart PS, Costerton JW. Antibiotic resistance of bacteria in biofilms. Lancet 2001;358;135-8.

Fig. 6