A Case Study on Septic Arthritis: Effects of Missed Diagnosis


This blog is a written by Mary Taylor a musculoskeletal physiotherapist and manager of a persisting pain service and orthopaedic interface clinic in Devon, UK. She wishes to highlight the need to be vigilant towards red flags, in particular septic arthritis, as this case study highlights the devastating consequences of missed early diagnosis.

We thank Mary again for her time in putting this together and for sharing it with us.

Septic Arthritis

Firstly let us discuss what septic arthritis is. It is an infection within a synovial joint, most commonly in the knee, but can also effect any synovial joint including hip, shoulder, elbow, ankle, wrist and small joints of the hand and foot. Usually caused by bacteria but can be caused by fungi or mycobacteria. (Carpenter, 2011).

Septic arthritis is a condition not to be missed and early diagnosis and appropriate management is crucial as delay or inadequate treatment can lead to irreversible cartilage damage within days, permanent joint damage and disability in 25% of cases and death in 11% -15% of cases (Reed, 2012). If delayed the infection will spread into the bone itself leading to osteomyelitis, which leads to bone destruction and if not treated effectively in the acute stages can lead to a chronic condition including sequestra and fistulae. (Faust S. Clark, J et. al. 2012).

Case Study

—A 19 year old fit healthy lifeguard and competitive sports man presents to Accident and Emergency Department complaining of significant foot and ankle pain at rest after going over on the ankle 3 days ago.

Septic Ankle/Foot

Photo of foot and ankle

Initially the ankle was not painful at the time of injury but he has he a significant increase in pain since and can no longer weightbear on the foot. See pictures of the foot/ankle.



Within the Accident and Emergency Department he underwent a X-ray of the foot and ankle and as no bone injury was seen he was discharged home.

Photo of Medial Malleolar Region

Photo of Medial Malleolar Region

He represented 2 days later in severe pain swelling foot and ankle, still unable to WB. A further foot and ankle X-ray was undertaken, showing no marked bony abnormality, and he was discharged home in a Camboot and given a follow up appointment in a week


2 days later he presented to an out of hours doctor service, adjacent to Accident and Emergency, still unable to weightbear and continuing increasing pain and swelling. He was diagnosed as an infection and given antibiotics,  in the form of oral Flucloxacillin which is a broad spectrum antibiotic. He did not present to Accident and Emergency on this occasion due to concern over further dismal of his problem.

Finally on the fourth presentation to Accident and Emergency with a painful and swollen foot and ankle, bloods were undertaken and revealed a CRP of 350 (normal lab range = 8).

He was then admitted under orthopaedics and an open washout was undertaken and IV antibiotics administered for 1 week and then discharged with oral flucloxacillin 6 weeks.

On review  2 weeks later an X-ray revealed talonavicular joint narrowing and a foot ankle MRI was ordered. As a consequence he was readmitted for subtalar and talonavicular joint wash out and again discharged on oral antibiotics.

At the 6 week clinic review he was still partial weight bearing on crutches and a week after finishing antibiotics he started feeling generally unwell and experienced increasing pain again in the foot/ankle. Bloods still showed a CRP of 70 and so an MRI of the foot and ankle was ordered and another washout followed by 6 weeks IV antibiotics and 6 weeks oral antibiotics.


Xray of the foot and ankle at 8 weeks after onset of symptoms

MRI T2 weighted image of ankle

MRI T2 weighted image of ankle









The imaging above shows destruction of the talus on X-ray and MRI T2 weighted image showing poor findings that indicate poor vitality in the talus. CRP at this time had increased again to 140.

Surgery was undertaken to remove the talus and antibiotics were commenced for recurrent infection.

3 months later a below knee amputation was undertaken due to ongoing symptoms and infection. A devasting outcome from such a trivial injury, due to an initial missed diagnosis.

The good news at the end of this debacle is that he is now within the training with the UK Para-Olympic triathlon team.

What To Look Out For

—Clinical presentation of a hot, swollen joint is common with a wide range of differential diagnoses. If clinical suspicion high treat as septic arthritis, even in absence of fever (Coakley G, 2006) as it has the most serious consequences –must not miss or delay care. (Reed, 2012)

Predisposing Factors

  • Trauma, particularly penetrating into the joint space or recent joint surgery
  • Immunosuppression such as in HIV, use of immunosuppressants, alcoholism, diabetes, malnutrition
  • Chronic inflammatory joint disease such as RA, SLE and recurrent gout; as bacteremia is more likely to localize in a joint with pre-existing arthritis,  particularly  if associated with  synovitis
  • IV drug use
  • Extremes of age, such as neonates and those greater than 80 years old.
  • Haematogenous spread (blood borne) from another site such as adjacent tissues like skin

Also note if infection is present then steroid injection into the joint will dramatically exacerbate the problem as it is an immunosuppressant (Coakley, G 2006; Mathews, C. et. al 2006)

Clinical Features

  • Joint Pain (sensitivity 85-100%), exacerbated by any movement (but note that a moveable joint also does not rule out the diagnosis of septic arthritis) and severe tenderness around the joint (sensitivity 100%, but only a single study).
  • Swelling and/or joint effusion may be seen, alongside warmth. Erythematous skin may appear but this is more characteristic of  overlying skin cellulitis or bursitis.
  • There will be antalgic gait or an inability to weight bear when joints of the lower limb are  involved.
  • Most cases involve a single joint however infection can involve 2-3 joints.
  • May be preceded or co-incide with skin, urinary tract or respiratory infection, especially in children.

There may be systemic disturbance such as nausea/ anorexia, fevers and myalgia, but absence of these does not rule out the diagnosis. Throughout these presentations in the case study the patient had fluctuating temperature readings.


  • Plain Radiography: Findings may be normal but may assist in ruling out alternative diagnoses (such as slipped upper femoral epiphysis, fractures or tumors). Look for soft tissue swelling around the joint, widening of the joint space, and displacement of tissue planes. In later stages of progression, look for bony erosions and joint space narrowing.
  • —MRI: Is sensitive detecting osteomyelitis. Early use MRI helps delineate extent of infection and aids in consideration for surgery.
  • Bloods and biochemistry: Full blood count may be unremarkable, including white cell count and ESR in early stages. CRP will be elevated (mean 183mg/l) and usually significantly higher than crystalloid arthropathies, such as gout.
  • Aspiration: Synovial fluid aspirate 94% sensitivity and 58% specific, and hence useful in diagnosis. Aspirate will be cloudy in appearance. If this is found on joint aspiration then send immediately to Accident and Emergency Department.

Learning From This Experience 

Hot, swollen, tender joint  with restricted movement =Septic Arthritis. UNTIL PROVEN OTHERWISE

Remember:    Delayed diagnosis  =  devastating effect.


  • Good history – don’t assume!
  • Check red flags to avoid missing significant pathology.
  • Worsening pain e.g. a sprained ankle impoves.


  • Include observations – limb temperature and core temperature, range, WB pain swelling.


  • —C reactive protein (CRP) is a useful measure and more sensitive than full blood count and ESR as ESR is slow to react to infection and hence, along with white blood cells, may not be elevated
  • —MRI much more sensitive and specific in picking up joint infection and osteomyelitis and the extent of the infection
  • —X-ray is of little value in early detection
  • Aspirate and analysis of synovial fluid is important as cloudy appearance can suggest infective process and analysis may help define the infective agent and hence provide a more effective treatment.


Needs to be as early as possible and note the use of antibiotics before joint aspiration reduces the chance of diagnosing the specific infective agent and compromises effect treatment.


  • Arnold, J., Cannavino, C., Ross, M., Ben Westley, B., Miller, T., Riffenburgh, R., Bradley, J. (2012) Acute Bacterial Osteoarticular Infections: Eight-Year Analysis of C-Reactive Protein for Oral Step-Down Therapy. PEDIATRICS: 130, 4, p.  e821.
  • Coakley G., Mathews C., Field M.,  Jones A., Kingsley G., Walker D., Phillips M., Bradish C,.  McLachlan A., Mohammed R., and Weston V., on behalf of the British  Society for Rheumatology Standards, Guidelines and Audit Working Group. (2006) BSR & BHPR, BOA, RCGP and BSAC guidelines for management of the hot swollen joint in adults. Rheumatology 45:1039 -1041. [ Accessed on line June 28 2016]
  • Fayad, Laura M; Carrino, John A; Fishman, Elliot K. (2007) Musculoskeletal infection: role of CT in the emergency department. Radiographics: a review publication of the Radiological Society of North America, Inc: 27, 6, pp. 1723-1736, 1527-1323
  • Faust, S., Clark, J., Pallett, A., Clarke, N. (2016) Managing bone and joint infection in children. Downloaded from http://adc.bmj.com/ on May 13, 2016 – Published by group.bmj.com
  • Genes, Nicholas; Chisolm-Straker, Makini. (2012) Monoarticular arthritis update: Current evidence for diagnosis and treatment in the emergency department.   Emergency medicine practice: 14; 5, pp. 1524-1971.
  • Thomas Gottlieb T., Atkins B,.and Shaw D., Series Editors: (2002) Soft tissue, bone and joint infections. Med J Aust 2002; 176 (12): 609-615. https://www.mja.com.au/journal/2002/176/12/7-soft-tissue-bone-and-joint-infections [Accessed 28th June 2016]
  • Hariharan, Praveen; Kabrhel, Christopher. (2011) Sensitivity of erythrocyte sedimentation rate and C-reactive protein for the exclusion of septic arthritis in emergency department patients. The Journal of emergency medicine: 40, 4, pp. 428-431, 0736-4679
  • Holtom PD; Borges L; Zalavras CG (2008) Hematogenous septic ankle arthritis. Clinical Orthopaedics & Related Research: 466, 6, pp. 1388-1391.
  • NUH ED pathway for all adult patient presenting with hot/swollen joint (s). Accessed on line http://www.rcem.ac.uk/Shop-Floor/Clinical%20Guidelines/College%20Guidelines/May, June 2016.
  • O’Malley, Anna; Svinos, Helene. (2009) Towards evidence based emergency medicine: Best BETs from the Manchester Royal Infirmary. BET 3: Is the white cell count of the joint aspirate sufficiently sensitive/specific to rule in/out septic arthritis? Emergency Medicine Journal : 26, 6, pp. 435-437, 1472-0213
  • Morrissy R.; Haynes,. (1989) Acute Hematogenous Osteomyelitis: A Model with Trauma as an Etiology. Journal of Pediatric Orthopaedics: Volume 9 (4) pp: 447-456.
  • Pääkkönen, M., Kallio, M., Kallio, P,. Peltola, H. (2013) C-reactive protein versus erythrocyte sedimentation rate, white blood cell count and alkaline phosphatase in diagnosing bacteraemia in bone and joint infections.  Journal of Paediatrics and Child Health 49 E189–E192
  • Pääkkönen, M., Peltola, H. (2013) Bone and Joint Infections.  Pediatric Clinic North America 60 pp. 425–436
  • Pääkkönen, M., Kallio M., Kallio P., Peltola H. (2011) Childhood osteomyelitis complicated by adjacent septic arthritis: antibiotic treatment and prognosis. Journal of pediatric Orthopaedics B: 20, 6, pp: 422-427
  • Pendleton A., Kocher M., (2015) Methicin-resistant Staphylococcus aureus Bone and joint infections in children. In Journal American Acadamy of Orthopaedic Surgeons: 23,1,PP 29-37. Prakash, M; Gupta, P; Sen,R; Sharma, A; Khandelwal, N. (2015) Magnetic resonance imaging evaluation of tubercular arthritis of the ankle and foot.   Acta radiologica: 56, 10 pp.1236-1241, 1600-0455.
  • Prakash, M; Gupta, P; Sen,R; Sharma, A; Khandelwal, N. (2015) Magnetic resonance imaging evaluation of tubercular arthritis of the ankle and foot.   Acta radiologica: 56, 10 pp.1236-1241, 1600-0455.
  • Reed, Matthew J; Carachi, Andrew (2012). Management of the nontraumatic hot swollen joint.  European journal of emergency medicine: official journal of the European Society for Emergency Medicine: 19, 2, pp. 103-107, 1473-5695
  • Royal Childrens Hospital Melbourne. Osteomyelitis and Septic Arthritis, Clinical Practice Guidelines.  Accessed online on 28th June 2016 http://www.rch.org.au/clinicalguide/guideline_index/Osteomyelitis_and_Septic_Arthritis/
  • Shadrick, Dan; Mendicino, Robert W; Catanzariti, Alan R. (2011) Ankle joint sepsis with subsequent osteomyelitis in an adult patient without identifiable etiologies: a case report. The Journal of foot and ankle surgery: official publication of the American College of Foot and Ankle Surgeons: 50, 3, pp. 354-360, 1542-2224.
  • Waryasz, Gregory R; McClure, Philip; Vopat, Bryan G. (2015)  Septic ankle with purulence tracking up the flexor hallucis longus tendon sheath leading to deep venous thrombosis/pulmonary embolism and compartment syndrome.   Foot & ankle specialist: 8, 3, pp. 234-239, 1938-7636.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s