Pediatric Knee Injury: A Unique Case of Intra-articular Osteochondral Fracture Following Penetrating Trauma

Penetrating injuries to the musculoskeletal system pose common challenges for orthopedic surgeons in emergency departments (EDs). The complexity escalates when a joint is affected, increasing the risk of severe complications such as infection and post-traumatic arthritis. Given the potential importance of these injuries, early diagnosis and a meticulous treatment plan are crucial. In this paper, we present a unique case of penetrating trauma, resulting in an intra-articular defect on the lateral femoral condyle of an adolescent girl. This case underscores the importance of tailored interventions in managing complex musculoskeletal injuries.

CT Scan versus Saline Load Test for Detection of Traumatic Wrist Arthrotomy

Background  Traumatic arthrotomy of the wrist is most commonly detected using the saline load test (SLT); however, little data exists on the effectiveness of the SLT to this specific joint. The use of computed tomography (CT) scan has been validated as an alternative method to detect traumatic arthrotomy of the knee, as the presence of intra-articular air can be seen when there is violation of the joint capsule. Question/Purpose  The purpose of this study was to determine the ability of CT scan to identify arthrotomy of the wrist capsule and compare the diagnostic performance of CT versus traditional SLT. Materials and Methods  Ten fresh frozen cadavers which had undergone transhumeral amputation were initially used in this study. A baseline CT scan was performed to ensure no intra-articular air existed prior to intervention. After baseline CT, an arthrotomy was created at the 6R radiocarpal portal site. The wrists then underwent a postarthrotomy CT to identify the presence or absence of intra-articular air. Following CT, the wrists were subjected to the SLT to detect the presence of extravasation from the arthrotomy. Results  Nine cadavers were included following baseline CT scan. Following arthrotomy, intra-articular air was visualized in eight of the nine cadavers in the postarthrotomy CT scan. Air was seen in the radiocarpal joint in eight of the nine wrists; midcarpal joint in seven of the nine wrists; and distal radioulnar joint in six of the nine wrists. All wrists (nine of the nine) demonstrated extravasation during the SLT. The mean volume of extravasation occurred at 3.7 mL (standard deviation = 2.6 mL), with a range of 1 to 7 mL. Conclusion  CT scan correctly identified eight of the nine simulated traumatic arthrotomies. Injection of 7 mL during the SLT was necessary to identify 100% of the arthrotomies. Clinical Relevance  CT scan is a sensitive modality for detection of traumatic arthrotomy of the wrist in a cadaveric model.

The "Fight Bite" Saline Joint Loading Test: Effectiveness in Detecting Simulated Traumatic Metacarpophalangeal Arthrotomies

Background: The saline load test is routinely used to recognize other joints' traumatic arthrotomies; however, there are currently no studies evaluating the novelty of this test for metacarpophalangeal joints (MCPJs). This study aimed to investigate the effectiveness and sensitivity of saline load testing in identifying the traumatic arthrotomies of the MCPJs using human cadavers. Methods: This was a cadaveric study of 16 hands (79 MCPJs). Traumatic arthrotomies were created using 11-blade stab-incisions, followed by blunt probing into the joint on the radial or ulnar side of the flexed MCPJs. A 3-mL syringe was used to inject intra-articular methylene-blue-dyed saline from the contralateral side. The volume at saline extravasation was recorded. Test sensitivity and factors influencing extravasation volume were assessed. Results: The mean (range) volume injected to identify arthrotomy of all MCPJs was 0.18 mL (0.1-0.4 mL). The mean volume to identify MCPJ arthrotomy of the thumb, index, long, ring, and small fingers was 0.16 mL (0.1-0.3 mL), 0.19 mL (0.1-0.3 mL), 0.21 mL (0.1-0.4 mL), 0.17 mL (0.1-0.3 mL), and 0.16 mL (0.1-0.3 mL), respectively. Cadaver age, laterality, and joint range of motion were not significantly associated with the injected volume at extravasation(P > .05, each). Injection volumes of 0.3 and 0.32 mL were required to detect arthrotomies at 95% and 99% sensitivities across all MCPJs. None of the MCPJs required > 0.4 mL to detect arthrotomy. Conclusions: Saline joint loading volumes to detect traumatic arthrotomy were similar for all MCPJs. Injection volumes of 0.32 mL is suggested for 99% sensitivity. Our findings provide the first report, to our knowledge, on intra-articular injection volumes expected to detect an arthrotomy of MCPJ. This is critical for further validation using in vivo clinical studies.

Can Ultrasound Identify Traumatic Knee Arthrotomy in a Cadaveric Model?

BACKGROUND

Traumatic arthrotomy of the knee (TAK) involves the violation of the knee capsule. TAK differs from simple lacerations because it requires operative management to prevent resultant septic arthritis. The diagnostic test of choice in the emergency department is the saline load test (SLT). SLT sensitivity ranges from 34% to 99%, depending on volume used. Computed tomography (CT) is a possible alternative, using intra-articular air as a diagnostic marker. Ultrasound can identify air in various tissues, given its highly echogenic nature.

OBJECTIVE

We sought to determine the sensitivity and specificity of ultrasound for detecting intra-articular air in cadaveric knee joints.

METHODS

Soft embalmed cadavers were utilized. The knees were block randomized to having 1 mL of air injected into the joint or sham skin injection. Two blinded, expert operators scanned the knees with a high-frequency linear transducer. The sensitivity and specificity were calculated.

RESULTS

Twenty knees were included. Knees that had any prior dissection were excluded from analysis. Ten knees were randomized for air injection. The pooled sensitivity was 0.65 (95% confidence interval [CI] 0.41-0.85) with a specificity of 0.75 (95% CI 0.48-0.93). Mean time taken was 143 s.

CONCLUSIONS

Ultrasound may have utility in evaluation of TAK. There were limitations. Some knees had effusions with echogenic material present, which could have led to false-positive results. It is also unknown how much air is typical of TAK. One milliliter was used based on previous work with CT. The use of ultrasound for diagnosis of TAK warrants further study.