Abstract
Arthroscopic techniques are effective for the removal of intra-articular bullet and metal fragments after gunshot wounds to the shoulder, hip, knee, and sacroiliac joints. Surgical removal of bullets retained within the synovial joints is indicated; lead is dissolved by synovial fluid over time, leading to proliferative synovitis, lead arthropathy, elevated serum lead levels, and lead toxicity. We present an arthroscopic technique for removal of a shotgun pellet retained within the medial meniscus. In this technique, diagnostic knee arthroscopy is initially performed, which allows for localization of the pellet within the medial meniscus. An up-biter is used to resect the inner rim of meniscus surrounding the pellet, and the pellet is removed with a grasper. This arthroscopic approach is advantageous because it allows for efficient visualization of the pellet within the meniscus, thorough visualization of all compartments of the knee, a reduction in blood loss, and a decrease in surgical morbidity to the surrounding cartilaginous, neurovascular, and soft-tissue structures. This technique may therefore be one option to address bullet fragments or shotgun pellets that are retained within the medial meniscus.
Gunshot wounds to the knee present challenges for both the patient and the treating orthopaedic surgeon. Arthroscopic removal of bullets and metal fragments has been reported as an effective treatment option for gunshot wounds to the shoulder, hip, knee, and sacroiliac joints.1, 2, 3 We describe a technique, with an associated instructional video (Video 1), in which arthroscopy is used for the removal of a shotgun pellet from the medial meniscus of the knee.
Technique Description
Patients presenting to the emergency department after gunshot wounds to the knee should initially be evaluated according to the Advanced Trauma Life Support protocol. A secondary survey can effectively identify other associated injuries. Vascular status is assessed with palpation of peripheral lower-extremity pulses bilaterally. A thorough neuromotor and neurosensory examination is also performed. Antibiotic prophylaxis (third-generation cephalosporin) and tetanus prophylaxis are administered. Radiographs of the knee are obtained, with orthogonal anteroposterior and lateral views. In the case of a shotgun wound, multiple shotgun pellets may be seen scattered throughout the knee on radiography, with pellets potentially retained in both intra-articular and extra-articular locations. The example in Figure 1 shows a pellet appearing intra-articularly within the medial compartment. If a bullet or pellet location looks questionable on radiography, a computed tomography scan of the knee should then be performed to confirm the intra-articular or extra-articular location of metallic fragments (Fig 1).
Fig 1.
Left knee radiographs and computed tomography scans. (A) Anteroposterior and (B) lateral radiographs are standard in the radiographic workup of a gunshot wound to the knee. For cases in which the missile appears intra-articularly on radiography, a computed tomography scan is next performed to confirm the intra-articular or extra-articular location of metallic fragments. In this example, 1 shotgun pellet is located intra-articularly within the medial compartment, just distal to the weight-bearing surface of the medial femoral condyle, as seen on the (C) coronal and (D) sagittal views.
After an intra-articular position of the bullet or pellet fragments has been confirmed, the patient thereby meets the indications for surgical removal, either with an open arthrotomy or with an arthroscopic approach. If bullet or pellet fragments are thought to be embedded in the meniscus, an arthroscopic approach may be a useful option. In this approach, the patient is positioned supine and is prepared and draped for diagnostic knee arthroscopy. An anterolateral portal is made using an inverted surgical scalpel with a No. 11 blade (Swann-Morton, Sheffield, England), just lateral to the patellar tendon and distal to the inferior pole of the patella. An arthroscopic sheath with a blunt obturator (Arthrex, Naples, FL) is aimed toward the notch and is used to enter through the knee capsule. The obturator is then removed from the sheath, and a 3.5-mm 30° arthroscope (Arthrex) is inserted into the knee through the sheath. Diagnostic arthroscopy begins in the patellofemoral compartment (Fig 2). The medial and lateral facets of the patella, as well as the trochlea, are inspected for signs of chondral injury. The arthroscope is then positioned in the suprapatellar pouch to look for metal fragments or projectiles. The medial gutter, lateral gutter, and popliteal hiatus are next visualized to identify any free-floating metal fragments, pellets, or bullet debris. With the arthroscope positioned in the medial compartment, an anteromedial portal is made under direct visualization. A hook probe (Arthrex) is then inserted through the anteromedial portal. The meniscal root, posterior horn, body, and anterior horn regions of the medial meniscus are probed and assessed for stability and for the presence of tears or metallic fragments (Fig 3).
Fig 2.
Knee diagnostic arthroscopy in left knee after gunshot wound. The diagnostic arthroscopy for a gunshot wound to the knee begins with the patient supine, the knee flexed to 90°, and the arthroscope inserted through the anterolateral portal. (A) The patellofemoral articulation is first visualized with the knee in extension. (B) With the arthroscope in this same position, the trochlea is next visualized by simply rotating the arthroscope 120°. (C) The arthroscope is then advanced into the suprapatellar pouch to look for metallic debris. The (D) lateral gutter and (E) medial gutter are then visualized; in this example, the shotgun pellet entered the joint, piercing the capsule of the medial gutter. (F) The popliteal hiatus is a common location for metallic debris and bullet fragments to collect and therefore must be thoroughly visualized. (G) The femoral condyles are then inspected for signs of articular cartilage damage. (H) The posterior compartment and the posterior horn of the medial and lateral menisci are inspected; loose bodies and bullet fragments can also collect posteriorly. (I) In this case example, there are no obvious signs of the shotgun pellet within the medial compartment at first glance.
Fig 3.
Shotgun pellet removal from medial meniscus in left knee. (A) The body of the medial meniscus is viewed through the anterolateral portal. The (B) superior and (C) inferior surfaces of the meniscus are then probed, assessing for any metallic debris or meniscal tears. (D) A reactive hyperemic synovial response near the capsular rim of the meniscus is a useful finding because it confirms the meniscal entry site of the pellet. An 18-gauge (18 G) spinal needle is next inserted through the anteromedial portal and is used to pierce the meniscus, probing for the pellet location. (E) The subtle finding of a dark structure beneath the superior surface of the meniscus (black arrow) is also a useful clue. (F) An up-biter punch is next inserted through the anteromedial portal and is used to trim the inner rim of the white-white zone, exposing the pellet location. (G) The shotgun pellet is removed with a grasper, and the inner rim of the meniscus is recontoured using a shaver. The removed pellet is then (H) photographed, (I) measured, and sent to police authorities for ballistic analysis.
Precise localization of the shotgun pellet can be challenging, especially if the pellet is embedded within the meniscus and not visible with use of the arthroscope. Additional arthroscopic clues are therefore necessary to localize the pellet. For wounds whereby the bullet or pellet enters the medial meniscus from the medial joint line of the knee, a hypervascular synovial response can be seen just peripheral to the meniscus at the zone of bullet entry (Fig 3). With the body of the medial meniscus reflected superiorly, this hypervascular synovial response can be seen just peripheral to the meniscus; this clue can help to localize the zone of injury and help to establish the precise location of the pellet within the meniscus (Video 1). For pellets embedded in the medial meniscus, a dark metallic hue can be seen just beneath the superior surface. This region of meniscus with a darker hue is then probed using an 18-gauge spinal needle inserted through the anteromedial portal, and the embedded pellet can be noted to be harder and more dense than the surrounding meniscal tissue (Fig 3). These steps aid in the confirmation of the precise location of the bullet or pellet within the medial meniscus.
Once the pellet location within the meniscus is accurately localized, a focal partial meniscectomy of the inner rim can be performed. To do so, a curved-shaft 15° Up WideBiter Punch Tip (Arthrex) is inserted through the anteromedial portal, and the inner rim of meniscal tissue surrounding the pellet is resected. Care is taken to resect the minimal amount of meniscal tissue necessary to expose the metallic pellet. The pellet is then visualized within the substance of the medial meniscus (Fig 3). The pellet is removed from the medial meniscus with an arthroscopic Alligator Grasper (Arthrex), measured, and sent to the police authorities for ballistic analysis (Video 1). The surrounding edges of the meniscal defect are then recontoured using a 3.5-mm SabreTooth straight arthroscopic shaver blade (Arthrex). The superior and inferior edges surrounding the meniscal defect are further debrided of loose tissue with the arthroscopic shaver. All loose meniscal fragments and debris are then removed with the arthroscopic shaver under high suction.
The anterior and posterior cruciate ligaments are probed and assessed for stability. The lateral compartment of the knee is then inspected for any further bullet fragments. The lateral meniscus is also probed and assessed for stability. Finally, the arthroscope is passed through the notch between the lateral border of the medial femoral condyle and the medial border of the posterior cruciate ligament and is positioned in the posterior compartment, which is inspected for any further metallic fragments, pellets, or loose bodies (Video 1). This step is crucial because metallic fragments from gunshot wounds to the knee are often free floating and can migrate throughout the compartments of the knee during arthroscopy; if the posterior compartment is not visualized, these fragments may be missed. The medial and lateral femoral condyles are then visualized through full flexion and extension range of motion and inspected for any sign of chondral injury. Finally, the knee is thoroughly irrigated with sterile arthroscopy fluid and drained, and the portals are closed. Postoperatively, the patient is allowed weight bearing as tolerated on the operative lower extremity.
Discussion
Arthroscopy has been recognized as an efficient means for bullet removal from the knee, hip, acetabulum, shoulder, and sacroiliac joints.1, 2, 3, 4, 5, 6 In our experience, the arthroscopic technique we hereby describe has proved successful for removal of a bullet or pellet from within the substance of the meniscus. Bullet fragments located within the synovial joints dissolve into the synovial fluid over time, leading to increased serum lead levels and chronic lead poisoning.7, 8 Manifestations of lead poisoning include anemia, motor neuropathy, encephalopathy, and nephropathy.7, 8 Retained bullet fragments within the joints may also lead to mechanical damage to the articular cartilage when weight bearing resumes. Lead fragments that remain intra-articular may also lead to proliferative synovitis and lead arthropathy.7 Surgical removal is therefore indicated for intra-articular lead or metallic bullet fragments after gunshot wounds to the knee.
The arthroscopic approach for bullet removal from the knee has numerous advantages over an open arthrotomy, including smaller incisions, decreased blood loss, a lower risk of associated injury to the neurovascular and soft-tissue structures, better visualization of associated osseous or chondral injuries, and a faster recovery time.1, 2, 3, 4, 5, 6 Metal foreign bodies can migrate within the knee, and arthroscopy allows for access to locations such as the popliteal hiatus and the posterior compartment that would otherwise be difficult to reach with an open arthrotomy approach.7 In the case of a shotgun pellet embedded within the medial meniscus, we have found that removing the shotgun pellet arthroscopically has major advantages over doing so with an open arthrotomy (Table 1). The magnified visualization of the arthroscope allows for more accurate localization of the pellet within the meniscus, as well as more efficient pellet removal with less untoward trauma to the surrounding cartilage. Diagnostic arthroscopy also enables more thorough visualization of all compartments of the knee, including the posterior compartment and popliteal hiatus; this visualization is more difficult with a single-incision open arthrotomy approach. Arthroscopic visualization ensures that no additional pellets or metal fragments are left behind. The arthroscopic technique also allows for thorough irrigation of the knee with the flow of sterile arthroscopy fluid.
Table 1.
Comparison of Open Versus Arthroscopic Techniques for Shotgun Pellet Removal in Knee
| Indications | Contraindications | Advantages | Disadvantages | |
|---|---|---|---|---|
| Open arthrotomy | GSW in knee with intra-articular bullet, pellet, or metal | Bullets retained in extra-articular location | Decreased risk of compartment syndrome | Greater risk of damage to neurovascular structures |
| Lead poisoning (plumbism) | Poor visualization of posterior compartment necessitates posterior knee approach | |||
| Lead arthropathy | Greater perioperative pain | |||
| Slower rehabilitation | ||||
| Arthroscopic | GSW in knee with intra-articular bullet, pellet, or metal | Bullets retained in extra-articular location | Smaller incisions | Risk of compartment syndrome due to fluid extravasation |
| Lead poisoning (plumbism) | High-energy tibial plateau fracture | Decreased blood loss | Hemarthrosis-related visualization difficulties | |
| Lead arthropathy | Faster rehabilitation | Mini-open arthrotomy needed for removal of larger bullet fragments | ||
| Lower risk of injury to neurovascular structures | ||||
| Access to shotgun pellets within meniscus | ||||
| Accurate localization of zone of injury | ||||
| Decreased iatrogenic trauma to adjacent articular cartilage | ||||
| Better visualization of popliteal hiatus and posterior compartment |
GSW, gunshot wound.
The disadvantages of an arthroscopic technique after any gunshot wound to the knee include the potential for poor visualization because of hemarthrosis and the risk of compartment syndrome due to extracapsular extravasation of arthroscopy fluid (Table 1). The described technique has limitations in that it is applicable only for pellets embedded in the white-white zone or in the red-white zone. For pellets embedded more peripherally in the red-red zone of the meniscus, resection of the meniscus extending from the inner rim peripherally would likely result in a larger than desired region of partial meniscectomy, leading to a detrimental increase in contact forces within the medial compartment (Table 2).9 In our experience, in the case of a shotgun wound to the knee with a retained pellet embedded in the red-white or white-white zone of the medial meniscus, the described arthroscopic technique is an effective approach for pellet removal.
Table 2.
Tips, Pearls, and Pitfalls of Arthroscopic Shotgun Pellet Removal From Meniscus
| Tips and pearls |
| Obtain a CT scan preoperatively to confirm the pellet location. |
| Perform a thorough diagnostic arthroscopy, including assessment of the popliteal hiatus and posterior compartment. |
| Perform careful management of arthroscopy fluid pressures to prevent extravasation and compartment syndrome. |
| Look for a hypervascular synovial/capsular response to help identify the zone of injury. |
| Probe any embedded pellets with a spinal needle to confirm their location. |
| Resect the minimal amount of meniscus needed to remove the pellet to preserve knee joint biomechanics. |
| Inspect for any missile-related articular cartilage damage. |
| Pitfalls |
| Failure to perform a preoperative CT scan contributes to difficulty with pellet localization. |
| An incomplete diagnostic arthroscopy of all compartments of the knee may result in unidentified metallic debris and loose bodies. |
| Failure to visualize the popliteal hiatus and posterior compartment can occur; pellet fragments and metal debris often collect is these locations. |
| Failure to accurately localize the pellet location within the meniscus may result in difficulties with extraction. |
| Resection of an excessive amount of meniscus leads to abnormal knee compartment biomechanics and subsequent osteoarthritis. |
CT, computed tomography.
Footnotes
The authors report that they have no conflicts of interest in the authorship and publication of this article.
Supplementary Data
Arthroscopic technique for the localization and removal of a shotgun pellet embedded in the medial meniscus of the left knee. With the patient in the supine position, the anterolateral portal serves as the primary viewing portal; a thorough diagnostic arthroscopic assessment of the patellofemoral, medial, lateral, and posterior compartments, as well as the popliteal hiatus, helps to identify any free-floating bullet fragments or metallic debris. Through the anteromedial portal, the pellet within the medial meniscus is probed with a spinal needle; once the pellet is localized, the inner rim is trimmed with a basket punch exposing the pellet, and the pellet is removed with a grasper.
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Associated Data
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Supplementary Materials
Arthroscopic technique for the localization and removal of a shotgun pellet embedded in the medial meniscus of the left knee. With the patient in the supine position, the anterolateral portal serves as the primary viewing portal; a thorough diagnostic arthroscopic assessment of the patellofemoral, medial, lateral, and posterior compartments, as well as the popliteal hiatus, helps to identify any free-floating bullet fragments or metallic debris. Through the anteromedial portal, the pellet within the medial meniscus is probed with a spinal needle; once the pellet is localized, the inner rim is trimmed with a basket punch exposing the pellet, and the pellet is removed with a grasper.