1.       Case Report

Arthroscopy of the knee joint is associated with a relatively low rate of complications, fewer than 2% [1-3]. We report an unusual and rare presentation of early subcutaneous emphysema of the thigh following arthroscopy with a fluid medium. This complication has been previously reported with carbon dioxide insufflation.

A 53-year-old female patient underwent arthroscopy of the left knee for a degenerative medial meniscal tear and arthroscopy debridement as a day-surgery procedure. It was performed under spinal anesthesia with tourniquet. The knee was irrigated with saline by arthroscopic pump. A partial medial meniscectomy was performed with an electric shaver under suction. After the procedure the fluid was drained out completely, no stitches were applied; dry dressings, and pressure bandage was given. The dressing was debulked at 48 h and knee exercises were started immediately post-surgery. Postoperatively the patient noticed swelling and tightness around the left thigh. The patient felt crackling-like sensation on rubbing his thigh. Clinical examination of the knee and thigh did not reveal any evidence of infection or effusion in the knee. Painless knee movements ranged from 0^° to 110^°. The anterolateral portal site was red, and a swab was taken from this wound. Blood tests were within normal limits.

Radiography (Figure 1) showed air in the subcutaneous tissue of the thigh and within the knee joint. Blood culture was negative.

Subcutaneous emphysema following arthroscopy has been reported in the literature when carbon dioxide was used to distend the joint with subsequent escape of the gas into the subcutaneous plane [4-8].

This complication was described for the shoulder arthroscopy [9-11]. Also reported are cases in which foot-operated saline pumps with loose junctions between bag and inflow tubing lead to air being pumped into the knee [12]. Hamilton [13] and Saleh [14] have described a similar mechanism of surgical emphysema in their case reports due to a chronic scar over the knee joint. Ferrnyhough [15] reported a mechanism resulting in “tension pneumoarthrosis” complicating a case of knee arthroscopy in which the portal had been used twice previously for an arthroscopy and twice for an arthrotomy. They stated that the dense scar tissue around the recurrent entry portal was a causative factor; their patient underwent arthroscopic irrigation in which the air was expelled and deep cultures taken, and the patient was put on intravenous antibiotics.

It is vital when faced with this clinical scenario to rule out infection due to gas gangrene forming organism [14]. It is also vital to be aware of this unusual presentation, as potentially serious consequences such as extension to the neck with breathing difficulties, pneumoperitoneum and pneumomediastinum have been reported in the literature [7,9-11,16].

Deshmukh decreed this complication with Saline whit gravity alone [17].

In the present case the knee was irrigated with saline by arthroscopic pump. We believe that this unusual occurrence was related to dysfunction of the arthrosopic pump that was not required for more time and that maybe inflow air in the knee. This mechanism was described from Calvisi [11] for the arthroscopy of shoulder.

The sheer stress on the wound due to absence of stitches and early knee mobilization exercises may have contributed. This exposed the subcutaneous tissue to the outside air that entered into the wound with every knee flexion and remained trapped in extension. The patient in our case report did not undergo any procedure and also made a full and uneventful recovery.

Figure 1: Radiography showed air in the subcutaneous tissue of the thigh and within the knee joint.

Figure 2: An MRI that confirmed the presence of air and exclude the infection.

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