Faculty Bibliography

OBJECTIVE:: To 1) determine the incidence and injury profile of open periarticular fractures about the knee joint in a cohort of patients presenting to the emergency department with a deep periarticular knee wound and to 2) determine the effectiveness of CT scan to detect and guide management of these open fractures compared to plain radiographs. DESIGN:: Retrospective Review SETTING:: Level I trauma center PATIENTS/PARTICIPANTS:: 78 patients (79 knees) with deep periarticular knee wounds of which 62 patients (63 knees) received both a plain radiograph and a CT scan of the knee. INTERVENTION:: Plain radiograph and CT scan of the injured knee. MAIN OUTCOME MEASUREMENTS:: Comparison of OTA fracture classification and surgeon produced management plan as determined by plain radiographs versus CT scans. CT scan was considered the gold-standard test to detect a fracture. RESULTS:: Twenty-one (27%, 21/79) knees had an open periarticular fracture of the knee and 95% (20/21) of these knees had intra-articular air indicative of an associated traumatic arthrotomy. Of 41 (52%, 41/79) knees with a traumatic arthrotomy, 51% (21/41) had an associated open periarticular fracture of the knee. Plain radiographs detected 18 fractures in 17 knees (of which 1 fracture was later determined to not be a true fracture) whereas CT scan detected 26 fractures in 21 knees. Overall, CT scan detected 9 additional fractures in 6 knees. The specificity and sensitivity and positive predictive and negative predictive values of plain radiographs to detect and rule-out a fracture was 98%/65% and 94%/82%, respectively. Compared to plain radiographs, CT scan altered the fracture classification in 48% of patients and altered the management plan in 43% of patients, respectively. Gunshot wounds to the knee had a 48% (12/25) incidence of an associated open periarticular fracture compared to an 17% (9/54) incidence for all other injury mechanisms combined (p<.01). CONCLUSION:: Patients with a periarticular knee wound have a high incidence of open periarticular fractures, and the incidence is even higher if the mechanism of injury is a GSW or there is associated traumatic arthrotomy. CT scan improves detection and management of open fractures of the knee compared to plain radiographs. Consideration should be given to routinely using CT scan to evaluate knees with deep periarticular wounds that present to the ED, especially if secondary to gunshot injuries, given the high incidence open periarticular fractures of the knee. LEVEL OF EVIDENCE:: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

OBJECTIVE:: To report our experience with computed tomography (CT) scans to detect traumatic arthrotomies of the knee joint (TAK) based upon the presence of intra-articular air. DESIGN:: Retrospective review SETTING:: Level I trauma center PATIENTS/PARTICIPANTS:: Sixty-two consecutive patients (63 knees) underwent a CT scan of the knee in the emergency department and had a minimum of 14 days follow-up. Cohort of 37 patients (37 knees) from the original 62 patients who underwent a Saline Load Test (SLT) INTERVENTION:: CT scan and SLT MAIN OUTCOME MEASUREMENTS:: Positive traumatic arthrotomy of the knee (+TAK) was defined as operating room (OR) confirmation of an arthrotomy or no intra-articular air on CT scan (-iaCT) (and -SLT if performed) with follow-up revealing a septic knee. Periarticular wound equivalent to no traumatic arthrotomy (pw=(-TAK)) was defined as OR evaluation revealing no arthrotomy or -iaCT (and -SLT if performed) with follow-up revealing no septic knee. RESULTS:: All 32 knees with intra-articular air on CT scan (+iaCT) had OR confirmation of a TAK and none of these patients had a knee infection at a mean follow-up of 140.0+/-279.6 days. None of the 31 patients with -iaCT had a knee infection at a mean follow-up of 291.0+/-548.1 days. Based on these results, the sensitivity and specificity of the CT scan to detect +TAK and pw=(-TAK) was 100%. In a subgroup of 37 patients that received both a CT scan and the conventional SLT, the sensitivity and specificity of the CT scan was 100% compared to 92% for the SLT (p<0.001). CONCLUSION:: CT scan performs better than the conventional SLT to detect traumatic knee arthrotomies and identify periarticular knee wounds that do not require surgical intervention and should be considered a valid diagnostic test in the appropriate clinical setting. LEVEL OF EVIDENCE:: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

OBJECTIVES:: To determine the lowest estimated radiation dose necessary to reproducibly detect intra-articular air in the knee joint of a cadaver model. METHODS:: 10 adult fresh-frozen cadaver knees with intact joint capsules provided by Science Care(R), Phoenix, AZ. were thawed and scanned at 5 decreasing radiation doses (decreasing by approximately half from 8.42 mGy to 0.74 mGy) after introducing increasing volumes (0 cc, 0.1 cc, 0.3 cc, 0.5 cc, 0.7 cc, 0.9cc) of intra-articular air. Scans were performed using 2.0 mm slice-thickness from the distal 1/3 of the femur to the proximal 1/3 of the tibia. Sagittal and coronal reconstructions of each scan using 1.0 mm slice-thickness were rendered. All scans were reviewed by 1) a single attending radiologist, 2) a single attending orthopedic surgeon, and 3) a single chief resident, for the presence of intra-articular air. RESULTS:: The sensitivity and specificity of CT scan to detect intra-articular air at each volume of intra-articular air (0.1 cc, 0.3 cc, 0.5 cc, 0.7 cc, 0.9cc) was 100% at 0.74 mGy - the radiation threshold dose (RadTH) (scan parameters: voltage 80kV, current: 33mA, and scan time: 12.17 sec). The effective radiation dose at 0.74 mGy for a CT scan of the knee is approximately 0.10 mSV CONCLUSIONS:: CT scan to detect traumatic knee arthrotomies can be successfully accomplished at a threshold radiation dose of 0.74 mGy and for an intra-articular volume of 0.1cc of air. This low radiation dose protocol and volume of intra-articular air should be taken into consideration with future studies evaluating the use of CT scan to detect traumatic arthrotomies.

OBJECTIVE:: To describe the use of the Saline Load Test (SLT) utilizing a new definition that more adequately characterizes its use in the emergency department (ED) setting. DESIGN:: Retrospective review SETTING:: Level I trauma center PATIENTS/PARTICIPANTS:: Fifty consecutive patients who underwent a SLT of the knee in the emergency department and had a minimum of 14 days follow-up. INTERVENTION:: Saline Load Test MAIN OUTCOME MEASUREMENTS:: Positive traumatic arthrotomy of the knee (+TAK) defined as OR confirmation of an arthrotomy (assumed to develop a septic knee) or -SLT with follow-up revealing a septic knee. Periarticular wound equivalent to no traumatic arthrotomy of the knee (pw=(-TAK)) defined as OR evaluation revealing no arthrotomy (assumed not to develop a septic knee) or -SLT whose follow-up revealed no septic knee. Development of a septic knee was considered the gold-standard for determining true positives/negatives and false positives/negatives. RESULTS:: The mean wound size was 3.9 +/- 4.3 cm and the mean saline load volume was 74.9 +/- 28.2 cm. There were 19 +SLTs of which there were 16 +TAK and 3 pw=(-TAK). The 3 pw=(-TAK) in the +SLT group were evaluated in the OR where inspection of the joint capsule revealed the absence of a traumatic arthrotomy. There were 31 -SLTs of which there were 1 +TAK and 30 pw=(-TAK). The SLT has a sensitivity of 94% and a specificity of 91% for detecting +TAKs and ruling-out periarticular wounds not requiring surgical intervention (pw=(-TAK)). The false-positive rate of the SLT to detect +TAK is 9%. CONCLUSION:: Using +TAK and pw=(-TAK) as the newly defined measures of the SLT, we report the sensitivity (94%) and specificity (91%) of the SLT in the ED setting while still maintaining the clinical relevancy of the test. Based on a small sample size, knees with small periarticular wounds and a -SLT and no other radiographic or clinical evidence of an arthrotomy appear to have an infection rate of 0% with non-operative management. LEVEL OF EVIDENCE:: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Wire breakage and migration is a known complication of using a wire tension band construct to treat displaced patella fractures. We report a case of a broken K-wire that migrated from the patella completely into the proximal tibia without complication 9 years after the index surgery. This report highlights the fact that wire migration can occur long after fracture healing and be relatively asymptomatic. But because the complications of wire migration can be deadly, it requires diligence on the part of the physician to educate the patient that new knee pain after operative fixation requires formal evaluation by the treating surgeon.

Standard techniques for immobilization of a tibia shaft fracture in the emergency department in a long-leg splint can be cumbersome, technically difficult, and often requires the use of an assistant. We have developed a novel technique for the reduction and splinting of tibial shaft fractures, which uses a 'hammock' constructed of stockinette, which allows a single consulting orthopaedic physician to rapidly reduce and place a long-leg plaster splint or cast on a patient. This technique was performed on 12 consecutive patients with a total of 12 tibial shaft fractures. Translation, angulation, and shortening of the fracture were documented in anteroposterior and lateral views of the injured tibia and these parameters were compared against values measured after the hammock technique was used to reduce and splint the fracture. Pre-'hammock' average values for fracture displacement in the anteroposterior plane for translation, angulation, and shortening were 10.5 mm (53.1%), 12.0 degrees , and 9.4 mm, respectively. Post-'hammock' average values for fracture displacement in the anteroposterior plane for the same parameters were 8.7 mm (44.4%), 4.2 degrees , and 7.9 mm, respectively. Pre-'hammock' average values for fracture displacement in the lateral plane for translation and angulation were 4.9 mm and 8.7 degrees . Post-'hammock' average values for fracture displacement in the lateral plane for the same parameters were 4.9 mm and 2.0 degrees , respectively. These results show that this technique is able to achieve the goals of fracture reduction and immobilization in a rapid fashion when help is not available