Abstract
Simple bone cyst is a common tumorlike lesion of the bone and can involve the bones of the foot. It is usually asymptomatic but can also present with pain or pathologic fracture. The purpose of this technical note is to describe the uni–osseous portal approach of endoscopic curettage and bone grafting of simple bone cyst of the navicular bone. The single-portal approach reduces the risk of iatrogenic fracture of the navicular bone. This is indicated for painful bone cyst of the navicular bone resistant to conservative treatment. It is contraindicated in multiple septated cysts, the presence of pathologic fracture, or the presence of aggressive cystic lesions.
Simple bone cyst is a common tumorlike lesion of the bone. Proximal humerus and proximal femur are the most common sites of involvement.1 It can also involve the bones of the foot. It is usually asymptomatic but can also present with pain or pathologic fracture. Surgery is indicated in the presence of pain resistant to conservative treatment methods, impending or pathologic fractures, and when a histopathologic diagnosis is required for differential diagnoses like aneurysmal bone cyst, giant cell tumor, or any other suspected aggressive bone lesion.1, 2, 3 Surgical treatment options for simple bone cyst include curettage in combination with autologous or allogenic grafting, the use of bone substitutes, autologous bone marrow injection, and various methods of cyst decompression including cannulated screws or a cannulated hydroxyapatite pin.1 Endoscopic curettage with bone grafting or injection of bone substitute has been reported for treatment of cystic lesions of the metatarsal,4 calcaneus,1, 5 and talus.6 Generally, 2–osseous portal approach is utilized.1, 4, 5, 6 The purpose of this technical note is to describe the uni–osseous portal approach of endoscopic curettage and bone grafting of simple bone cysts of the navicular bone. It is indicated for simple bone cysts of the navicular bone associated with pain resistant to conservative treatment. It is contraindicated in multiseptated lesions or the presence of pathologic fracture. Aggressive cystic lesions, for example, aneurysmal bone cyst is a relative contraindication for endoscopic procedure as en bloc resection is usually indicated (Table 1).7, 8, 9, 10
Table 1.
Indications and Contraindications of Endoscopically and Fluoroscopically Assisted Curettage and Bone Grafting of the Navicular Bone Cyst
| Indications | Contraindications |
|---|---|
| 1. Simple solitary bone cyst of the navicular bone | 1. Multiple septated lesions |
| 2. Presence of pathologic fracture | |
| 3. Aggressive cystic lesion (e.g., aneurysmal bone cyst) |
Technique
Preoperative Planning and Patient Positioning
Preoperative magnetic resonance imaging and computed tomogram can confirm the diagnosis and study the location, dimension and architecture of the navicular bone cyst (Fig 1).
Fig 1.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. Preoperative magnetic resonance imaging ([A] axial view; [B] sagittal view) and computed tomogram ([C] coronal view; [D] sagittal view) of the illustrated case confirm the diagnosis and study the location, dimension, and architecture of the navicular bone cyst (arrowhead).
The patient is in supine position with a thigh tourniquet to provide a bloodless operative field. A 2.7-mm 30° arthroscope (Henke-Sass, Wolf, Tuttlingen, Germany) is used for this procedure.
Portal Placement
The dorsolateral and lateral midtarsal portals are used for this procedure.11, 12, 13 The dorsolateral midtarsal portal is located at the junction between the talonavicular and calcaneocuboid joints. The lateral midtarsal portal is located at the plantar lateral corner of the calcaneocuboid joint (Fig 2). The dorsolateral midtarsal portal is also one of the portals of talonavicular arthroscopy and can be used to examine the talonavicular joint. Three- to 4-mm incisions are made at the portal sites. The underlying soft tissue is bluntly dissected to the lateral wall of the navicular bone.
Fig 2.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. The dorsolateral midtarsal portal (DLMP) is located at the junction between the talonavicular and calcaneocuboid joints. The lateral midtarsal portal (LMP) is located at the plantar lateral corner of the calcaneocuboid joint.
Exposure of the Lateral Cortex of the Navicular Bone
The lateral midtarsal portal is the viewing portal. The soft tissue over the lateral wall of the navicular bone is stripped by an arthroscopic shaver (Dyonics; Smith & Nephew, Andover, MA) via the dorsolateral midtarsal portal (Fig 3). The lateral part of the capsule of the talonavicular joint is also resected to expose the articular cartilage. Arthroscopic synovectomy can be performed if there is synovitis of the talonavicular joint.
Fig 3.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. The lateral midtarsal portal is the viewing portal. The soft tissue over the lateral wall of the navicular bone (N) is stripped by an arthroscopic shaver via the dorsolateral midtarsal portal. (T, talar head.)
Bone Tunnel to the Navicular Bone Cyst
The lateral midtarsal portal is the viewing portal. The bone tunnel is made from the lateral navicular wall to the bone cyst. This is performed by sequential drilling with a 1.6-mm K-wire (Zimmer, Warsaw, IN), 2.5-mm drill bit, and 3.5-mm drill bit via the dorsolateral midtarsal portal (Fig 4). Sequential drilling with increasing drill size avoids iatrogenic fracture. The direction and depth of the drilling is guided by fluoroscopy.
Fig 4.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. The lateral midtarsal portal (LMP) is the viewing portal. (A) The bone tunnel is made from the lateral navicular wall to the bone cyst. A bone tunnel is created by drilling the lateral cortex of the navicular bone toward the bone cyst. (B) Arthroscopic view of the bone tunnel (BT) of the lateral navicular (N) wall. (DLMP, dorsolateral midtarsal portal; T, talar head.)
Endoscopically and Fluoroscopically Assisted Curettage of the Navicular Bone Cyst
The dorsolateral midtarsal portal is used alternatively as the viewing and working portal. The arthroscope is inserted into the bone tunnel via the dorsolateral midtarsal portal. The bone cyst and its lining are assessed arthroscopically (Fig 5). The arthroscope is then removed and an arthroscopic curette (Acufex; Smith & Nephew) is inserted into the cyst via the dorsolateral midtarsal portal. The cyst wall is curetted under fluoroscopic guide (Fig 6). The curette is then replaced by the scope. The loosened fibrous membrane can be seen. The scope is replaced by the arthroscopic shaver and the loosened fibrous membrane is resected by the shaver (Fig 7). The steps are needed to be repeated a few times before completion of cyst wall debridement (Fig 8). Frequently, bubble is introduced into the cyst during insertion of the instruments into the bone tunnel. The bubble can be expelled by internal rotation of the leg, withdrawal of the scope to the orifice of the bone tunnel, and pumping normal saline into the bone cyst.
Fig 5.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. (A) The arthroscope is inserted into the bone tunnel via the dorsolateral midtarsal portal (DLMP). (B) The bone cyst (BC) and its fibrous membrane (FM) are assessed arthroscopically. (BT, bone tunnel.)
Fig 6.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. (A) An arthroscopic curette (Acufex; Smith & Nephew) is inserted into the cyst via the dorsolateral midtarsal portal (DLMP). The cyst wall is curetted under fluoroscopic guide ([B] dorsoplantar view; [C] lateral view).
Fig 7.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. (A) The dorsolateral midtarsal portal is the viewing portal. The fibrous membrane loosened by the curette can be seen. (B) The scope is replaced by the arthroscopic shaver and the loosened fibrous membrane is resected by the shaver. (BT, bone tunnel; DLMP, dorsolateral midtarsal portal; LFM, loosened fibrous membrane.)
Fig 8.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. The dorsolateral midtarsal portal is the viewing portal. The bone cyst (BC) is completely debrided. (BT, bone tunnel.)
Endoscopically and Fluoroscopically Assisted Bone Grafting of the Navicular Bone Cyst
The lateral midtarsal portal is the viewing portal. A 3.5-mm drill guard loaded with cancellous autograft is inserted into the orifice of the bone tunnel via the dorsolateral midtarsal portal (Fig 9). Bone graft is delivered to the bone tunnel and the bone cyst by a trocar (Video 1, Table 2). The direction and depth of the trocar is checked by fluoroscopy. The grafting procedure is repeated until the cyst and the bone tunnel is completely grafted. Postoperatively, the foot is immobilized by a short leg cast for 6 to 8 weeks.
Fig 9.
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. The lateral midtarsal portal is the viewing portal. The drill guard (DG) loaded with cancellous bone graft is inserted via the dorsolateral midtarsal portal and placed to the orifice of the bone tunnel (BT).
Table 2.
Pearls and Pitfalls of Endoscopically and Fluoroscopically Assisted Curettage and Bone Grafting of the Navicular Bone Cyst
| Pearls | Pitfalls |
|---|---|
| 1. Sequential drilling with increasing drill size reduces the risk of iatrogenic fracture. | 1. Curettage of the proximal and distal wall of the bone cyst should be performed with caution to avoid perforation of the articular surfaces. |
| 2. Uni–osseous portal approach reduces the risk of iatrogenic fracture. | 2. The lateral wall of the cyst is the blind spot of this procedure. |
| 3. The dorsolateral midtarsal portal is used alternatively as the viewing and working portals for the endoscopic curettage and grafting of the bone cyst. | 3. Multiseptated lesions increase the risk of recurrence as some of the cysts may be left untouched. |
| 4. The endoscopic curettage and grafting is guided by intraoperative fluoroscopy. | |
| 5. The bubble of the bone cyst can be expelled by proper positioning of the arthroscope and the operated leg. |
Discussion
Compared with the long bone of the extremities, the bones of the foot are small. The cortical window used for open curettage of the bone cyst of the foot is small, and blind spots exist. Under the magnifying view of arthroscopy, there are fewer blind spots in the operative field and a thorough curettage could be performed.1 Moreover, the bone window for open curettage is larger than that required for endoscopic curettage. This can weaken the cortical structures of the bone and increase the risk of fracture.1 Two osseous portals are needed to allow curettage under direct arthroscopic visualization. This is possible for the larger bone of the foot.1, 4, 5, 6 However, the navicular bone is small, and 2 osseous portals will significantly weaken the bone and increase the risk of pathologic fracture. In this reported technique, the same osseous portal is used alternatively as the viewing and working portal. The location of the osseous portal depends on the location of the bone cyst. Ideally, the portal should be placed so that the distance between the cyst and the portal is shortest. For the plantarly located cyst, as in this illustrated case, a plantar osseous portal is ideal but practically impossible. The medial osseous portal has the risk of avulsion fracture of the navicular tubercle and loss of action of the tibialis posterior. The dorsal osseous portal put the medial cutaneous branch of superficial peroneal nerve at risk. The lateral osseous portal has been used because establishment of the lateral osseous portal and bone grafting can be performed under an endoscopic guide. This is essentially an endoscopic procedure, and the working space is larger than that of the dorsal or medial approach. Both the lateral cortical wall of the navicular bone and the lateral part of the talonavicular joint can be accessed via the same approach.
The issue after curettage of the cyst is how to reconstruct the bone defect. Curettage with augmentation demonstrated significant improvements over curettage with cannulated-screw placement.1 Bone cement, bone graft, and other alternatives have been used to augment the bone defect. Reconstruction with cement can make immediate weight-bearing possible without risk of fracture and can improve radiographic follow-up. However, the long-term effect of cement on the articular surface of the bone remains unknown, but it is possible that arthritis may develop, because of the nonanatomic construction of the cement.1 Endoscopic curettage and injection of bone substitute has been proposed to minimize the risk of postoperative pathologic fracture and local recurrence after early return to initial level of sports activities.5 At present, biological reconstruction using bone graft seems to be the best option. The advantages of autograft include improved rate of graft incorporation and lack of immunogenic concerns; however, it may need a longer operating time and can result in donor morbidity.14, 15 Use of allograft is an alternative option. However, fracture and nonunion are common complications for allograft. There is also a risk of transmitting disease with allograft; however, with safety precautions, including donor selection and biological investigations, such risks are low.15 We use autograft in our technique as allograft is not readily available in our locality.
The advantages of this endoscopic technique include small incisions and better aesthetical results, little blood loss, limited dissection, and less scarring, less pain, low cost, and early rehabilitation.1, 4, 5 The potential risks of this technique include injury to the motor branch to the extensor brevis, iatrogenic fracture of the navicular bone, injury to the articular surfaces of the navicular bone, failure of graft incorporation, and recurrence of the bone cyst (Table 3).
Table 3.
Advantages and Risks of Endoscopically and Fluoroscopically Assisted Curettage and Bone Grafting of the Navicular Bone Cyst
| Advantages | Risks |
|---|---|
| 1. Uniportal approach reduces the risk of iatrogenic fracture | 1. Injury to the motor branch to the extensor brevis |
| 2. The same approach can access both the lateral part of the talonavicular joint and the navicular bone cyst | 2. Iatrogenic fracture of the navicular bone |
| 3. Small incisions and better aesthetical results | 3. Injury to the articular surfaces of the navicular bone |
| 4. Little blood loss | 4. Failure of graft incorporation |
| 5. Limited dissection, less scarring, and less pain | 5. Recurrence of the bone cyst |
| 6. Low cost | |
| 7. Early rehabilitation |
Footnotes
The author reports that he has no conflicts of interest in the authorship and publication of this article.
Supplementary Data
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. The lateral midtarsal portal is the viewing portal. The soft tissue over the lateral wall of the navicular bone is stripped by an arthroscopic shaver via the dorsolateral midtarsal portal. The lateral navicular wall is drilled to create a bone tunnel to the bone cyst. The dorsolateral midtarsal portal is then used alternatively as the viewing and working portals during endoscopic curettage of the bone cyst. After completion of debridement of the bone cyst, the lateral midtarsal portal is used as the viewing portal. A drill guard loaded with cancellous bone graft is inserted via the dorsolateral midtarsal portal and placed to the orifice of the bone tunnel. Bone graft is then delivered to the bone cyst.
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Associated Data
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Supplementary Materials
Endoscopically and fluoroscopically assisted curettage and bone grafting of the right navicular bone cyst. The lateral midtarsal portal is the viewing portal. The soft tissue over the lateral wall of the navicular bone is stripped by an arthroscopic shaver via the dorsolateral midtarsal portal. The lateral navicular wall is drilled to create a bone tunnel to the bone cyst. The dorsolateral midtarsal portal is then used alternatively as the viewing and working portals during endoscopic curettage of the bone cyst. After completion of debridement of the bone cyst, the lateral midtarsal portal is used as the viewing portal. A drill guard loaded with cancellous bone graft is inserted via the dorsolateral midtarsal portal and placed to the orifice of the bone tunnel. Bone graft is then delivered to the bone cyst.