TKA complications Increased risk with notching anterior femur, surgical trauma to quadriceps, distal femur exposure and periosteal stripping, and postop manipulation under anesthesia, and high lumbar BMD
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A 24-year-old male presents with a painful, stiff elbow after sustaining an injury 4 months ago. A radiograph is shown in Figure A. Which of the following statements is true about his condition?
Early excision has been found to decrease rate of recurrence compared to excision after maturity
Radiographs may be used to assess maturity of the lesion
Bone scan will always be negative once the lesion is considered mature
The lesion is considered mature 12 months after initial radiographic findings are seen
Alkaline phosphatase level measurements are used to determine the maturity of the lesion
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Radiographs are extremely useful in the staging of heterotopic ossification, and will show the development of sharp cortical margins once the lesion has reached maturity.
Heterotopic bone is a condition in which lamellar bone forms in non-ossified soft tissues. In the early stages, studies such as MRI and bone scan are more sensitive for diagnosis, as radiographs may appear normal for the first three weeks. After the appropriate diagnosis is made, sequential radiographs are useful for monitoring the progression of the ossification. Once it has reached the mature stage, sharp cortical margins will appear, and surgical resection may be considered.
Cipriano et al. review heterotopic ossification following traumatic brain and spinal cord injuries. They discuss that the rate of radiographic recurrence is high (82-100%), but that that the rate of clinically significant recurrence is much lower (17-52%).
Figure A is a lateral radiograph of an elbow showing extensive heterotopic ossification with sharp cortical margins. This is consistent with heterotopic ossification in the mature stage.
Answer 1: Waiting for maturity has been found by some studies to decrease the chance of recurrence when compared to early excision.
Answer 3: Bone scans may still be positive after the lesion has reached maturity.
Answer 4: Duration from initial injury does not always correlate with level of maturity.
Answer 5: Alkaline phosphatase levels may aid in the diagnosis of heterotopic ossification, but are not used to assess the level of maturity of the lesion.
Cipriano CA, Pill SG, Keenan MA.
J Am Acad Orthop Surg. 2009 Nov;17(11):689-97. PMID: 19880679 (Link to Abstract)
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A 27-year-old man is involved in a motor vehicle crash and sustains a closed head injury and right intertrochanteric hip fracture with ipsilateral femoral head fracture. He undergoes operative stabilization of his right hip. At 1 year follow-up he has limited rotation and abduction of the hip. Radiographs are shown in Figures A and B. What intervention during his initial treatment could have potentially prevented this outcome?
700 cGy of radiation within 72 hours of surgery
Pulsed administration of recombinant PTH 1,34 postoperatively for 1 year
3 cycles of VAC (Vincristine, Actinomycin D, and Cyclophosphamide)
700 cGy of radiation 2 weeks prior to surgery
3 treatments of 700 cGy of radiation divided over 1 week after surgery
The patient has post-traumatic heterotopic ossification (HO). HO can occur about the hip following acetabular and hip fractures as well total hip arthroplasties (THA). Comprehensive Orthopaedic Review puts the incidence as high as 80% in THA patients and Miller's states that it is seen most with the direct lateral approach in THA and extensile approaches for acetabular fractures. The presence of a head injury makes an orthopedic trauma patient high risk for HO.
Board et al conducted a review of HO following THA and found that in high risk individuals 700-800 cGY delivered less than 4 hours preoperatively or within 72 hours postoperatively appeared to be more effective than indomethacin 75mg daily for 6 weeks.
Ayers et al also conducted a review of the literature and concluded that localized radiation was the treatment of choice to prevent heterotopic ossification following cementless total hip arthroplasty in high risk individuals.
Irradiation prevents proliferation and differentiation of primordial mesenchymal cells into osteoprogenitor cells that can form osteoblastic tissue. Oral bisphosphonates are not effective for prophylaxis as they inhibit mineralization of osteoid, but do not prevent the formation of osteoid matrix and when bisphosphonate therapy is discontinued, mineralization with formation of HO may occur. VAC (Answer 3) is a chemotherapy regimen used in Ewings sarcoma treatment. Recombinant PTH 1,34 (Answer 2) has been shown to increase bone mineral density.
Board TN, Karva A, Board RE, Gambhir AK, Porter ML
J Bone Joint Surg Br. 2007 Apr;89(4):434-40. PMID: 17463108 (Link to Abstract)
Ayers DC, Pellegrini VD Jr, Evarts CM.
Clin Orthop Relat Res. 1991 Feb;(263):87-93. PMID: 1899641 (Link to Abstract)
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Which amputation patient would have the highest risk of developing heterotopic ossification at the amputation site?
75-year-old diabetic with an ischemic limb undergoing a transtibial amputation
45-year-old woman that had a propane tank explode near her thigh undergoing a transfemoral amputation
25-year-old army captain with a complex blast injury to his shin undergoing transfemoral amputation
65-year-old with necrotizing fasciitis of his lower leg undergoing knee transfemoral amputation
35-year-old woman with a grade IIIC open distal tibia fracture who elects for a below the knee amputation
Heterotopic ossification (HO) most commonly occurs at the amputation site if the amputation was performed thru the zone of injury, especially if the injury was a blast mechanism.
Potter et al reviewed 213 military amputations and found heterotopic ossification was present in 63% of the residual limbs. A final amputation level within the zone of injury and a blast mechanism were risk factors for the development of heterotopic ossification. Symptomatic HO was removed successfully with a low recurrence rate (<10%).
Other answers listed describe amputations at a level above the zone of injury.
Potter BK, Burns TC, Lacap AP, Granville RR, Gajewski DA
J Bone Joint Surg Am. 2007 Mar;89(3):476-86. PMID: 17332095 (Link to Abstract)
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Heterotopic ossification has been recognized as a rare complication from Steinmann pins placed in which location for traction purposes?
Symptomatic heterotopic ossification of the quadriceps may occur following placement of a large-diameter Steinmann pin for the purpose of temporary skeletal traction. This potential complication should be considered when using a large-diameter Steinmann pin in the distal femur for skeletal traction. The other locations have not been recognized as areas for heterotopic ossification.
The referenced study reported on a case series of symptomatic quadriceps heterotopic ossification as a result of large diameter traction pin placement into the distal femur.
Specht LM, Gupta S, Egol KA, Koval KJ.
J Orthop Trauma. 2004 Apr;18(4):241-6. PMID: 15087970 (Link to Abstract)
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Which of the following has not been shown in the literature to increase the risk of heterotopic ossification?
Prolonged ventilator time in multiply traumatized patients
Spinal cord injury
Amputation through the zone of injury in patients injured in blasts
Heterotopic ossification is the formation of bone outside of the skeleton - often occuring within skeletal muscles. Illustrations A and B are representative examples of heterotopic ossification around the elbow and following a total hip arthroplasty. Around the hip, heterotopic ossification is classified via the Brooker classification (Illustration C). It is caused by activation and proliferation of mesenchymal stem cells and is an active research area in trauma and rehabilitation. Prolonged ventilator time, brain injury, spinal cord injury, burns, neurologic compromise (measured via GCS), and amputation thru the zone of injury in a patient injured in a blast are all literature proven risk factors for development of heterotopic ossification.
Pape et al retrospectively studied heterotopic ossifications in patients with blunt multiple trauma with and without associated head injury. They evaluated two cohorts of patients at risk for development of heterotopic ossification and found prolonged ventilation times in multiply traumatized patients was associated with an increased risk of development of heterotopic ossification.
Pape HC, Lehmann U, van Griensven M, Gänsslen A, von Glinski S, Krettek C
J Orthop Trauma. 2001 May;15(4):229-37. PMID: 11371787 (Link to Abstract)
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A 32-year-old male sustains a the injury shown in Figure A after a high-speed motor vehicle collision. Which factor has been found to have the highest direct correlation with severe heterotopic ossification after traumatic knee dislocation?
Injury Severity Score (ISS)
Glascow Coma Scale (GCS)
Timing of knee reconstruction
Number of ligaments reconstructed
Open ligament reconstruction
Figure A shows a knee dislocation with cruciate ligament avulsion injuries. Development of significant heterotopic ossification (HO) formation has been shown to be most directly correlated to the ISS score.
Mills and Tejwani looked at multiple variables including injury severity score (ISS), Glascow coma scale (GCS), closed head injury (CHI), timing of surgery (> or < 3 weeks) and type of surgery (open vs. arthroscopic, number of ligaments reconstructed) in its relation to the formation of HO following knee dislocation. In the final group the sensitivity and specificity of the ISS in relation to HO formation was 100%, while presence of CHI had a specificity of 97%. Timing, type of surgery and approach did not influence HO formation.
Mills WJ, Tejwani N.
J Orthop Trauma. 2003 May;17(5):338-45. PMID: 12759638 (Link to Abstract)
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