Various surgical techniques, such as corticocancellous or cancellous bone graft and other vascularized bone grafting techniques have been developed to treat scaphoid nonunion. However, open grafting with dissection of wrist capsule and ligaments damages the joint and hence can lead to increased stiffness of the wrist and hand. Arthroscopic assisted bone grafting and percutaneous fixation have advantages such as minimal surgical trauma to the scaphoid blood supply and its ligament connection and provide a thorough wrist assessment, comprehensive approach for scaphoid nonunion and its sequelae in a minimally invasive manner. This article briefly discusses the characteristic anatomy of the wrist and scaphoid, and reviews the technique of arthroscopic bone grafting and percutaneous fixation for the treatment of scaphoid nonunion.
Untreated scaphoid nonunion progresses to carpal collapse resulting in wrist arthritis and chronic painful disability [
After the introduction of wrist arthroscopy by Chen [
The wrist can be considered as the most complex synovial joint in the human body, consisting of 15 bones with 27 articulation surfaces and numerous ligamentous connections. Among them, the scaphoid is an almost entire intraarticular bone and 80% of the bone is covered by cartilage, which allows only few potential sites for the entrance of perforating vessels. The scaphoid has a tenuous blood supply [
Therefore, if arthroscopy is applied to the scaphoid, ligament injury can be avoided, the scaphoid can be completely assessed through mid-carpal and radio-carpal joint, and the blood supply to the scaphoid can be preserved as much as possible.
Whipple first applied wrist arthroscopy in the treatment of scaphoid fracture and reported the combined advantages of internal fixation and minimal invasive surgical technique [
In proximal pole nonunion, humpback of dorsal intercalated segment instability (DISI) deformity is uncommon. Moreover, scaphoid nonunion advanced collapse (SNAC) progresses more slowly and there is usually a flat crescent-like smaller bone defect. However, due to the lack of surrounding ligaments or capsules in the nonunion site, and in very proximal fracture, the nonunion site can be directly communicating with the radio-carpal joint. The grafted bone may escape from the graft site, so caution is required during bone grafting. To avoid spillage of bone graft from the nonunion site, only fibrous and necrotic tissue should be removed while preserving the cortical shell as much as possible. Wong and Ho [
Distal pole nonunion occurs relatively less often. It is more difficult to perform arthroscopic operation because the nonunion site is unstable when the wrist is distended. Moreover, the surgeons should be aware of the difficulty of reduction and fixation of the nonunion site.
Arthroscopy in scaphoid nonunion can have diagnostic and therapeutic roles. The diagnostic roles are (1) confirmation of the healing status of the fracture site; (2) assessment of the possibility of healing potential, i.e., the presence of punctate bleeding; (3) assessment of the cartilage status; (4) assessment of associated injuries that account for the symptoms, especially the ulnar side wrist pain; and (5) more comprehensive assessment of combined injuries such as scapho-lunate (SL), luno-triquetral (LT), triangular fibrocartilage complex (TFCC) injuries, and chondral injuries [
The operation is performed under general anesthesia with the patient positioned supine on the side of the iliac crest region draped for bone graft harvesting. The arm to be operated is placed in a wrist traction tower and a vertical traction of 4−6 kg force applied through plastic finger trap devices to the middle 3 fingers for joint distraction on a hand table. An arm tourniquet is applied and inflated only if necessary, and a C-arm image intensifier is prepared for the percutaneous scaphoid fracture reduction and K-wires fixation.
We use a 2.5- or 1.9-mm video arthroscope (CONMED, Utica, NY, USA), 2.0 mm and 2.9 mm shavers, a 3.0-mm burr, and a radiofrequency probe for surgical instruments. We also use 2 custom-made cannulas (3.8 mm and 3.0 mm) and 2 custom-made trocars (3.2 mm and 2.7 mm) for percutaneous bone grafting (
An inspection is first done on the radio-carpal joint. For a radio-carpal examination, first, the 3/4 portal is established as the viewing portal. The outflow is commonly made at 6U using an 18 gauge needle. From the 3/4 portal, it is possible to look at the dorsal ridge of the scaphoid where capsular reflection is attached, by orienting the arthroscope dorso-radially along the curvature of the scaphoid. When looking downward, the radial styloid process can easily be reached. From there inwards, the palmar capsular ligaments, the interosseous ligament, the TFCC, and articular cartilage should be evaluated systemically. During arthroscopy, carpal ligament injuries were graded using the system described by Geissler et al. [
Takedown of nonunion site is carried out through the mid-carpal joint with the MCU as the viewing portal. The fracture gap is directly palpated with a probe inserted through the MCR portal. If a frank bone defect is encountered, both ends of the nonunion site are debrided and burred to remove all fibrotic tissue and sclerotic bone by switching the burr and shaver to the MCR and accessory portals until healthy looking cancellous bone with punctate bleeding is visible. Any intact cartilage around the nonunion site should be preserved for better graft containment. Since we do not use a tourniquet, a punctate bleeding can be seen during the debridement. Both ends are inspected for punctate bleeding with inflow irrigation fluid immediately stopped when no distinct bone bleeding is observed, despite the sufficient removal of necrotic bone (
After sufficient debridement and removal of necrotic bone, the 2 fragments of the nonunion should be mobile enough for subsequent reduction. The distal fragment is reduced to the proximal fragment under the C-arm image intensifier by traction, gentle passive ulnar deviation, hypersupination and extension of the wrist with a surgical towel placed under the forearm and a 1.2 mm K-wire is inserted percutaneously from the tubercle of the scaphoid to the proximal pole for provisional scaphoid fixation (
After preparing the bone grafting, cancellous bone graft is harvested from the iliac crest instead of distal radius using an open approach through a small incision. The quality of the iliac bone is superior. The volume of the harvested bone graft has to be at least 3 to 5 times that of the defect because the graft needs to be tightly compressed into the defect to increase the strength of the graft. The bone graft is then cut into small chips using scissors (
For bone grafting, an arthroscope is introduced in the MCU portal to continuously show the nonunion site, a custom-made 3.8 mm cannula is introduced to the nonunion site through the MCR portal, and cancellous chip bone is delivered to the entrance of the cannula. The bone graft is packed with a 3.2-mm trocar until a satisfactory volume of graft is achieved (
Definitive fixation with two 1.2-mm K-wires is performed under the C-arm image intensifier. Additional SL K-wires fixation is performed to fix the unstable nonunion and kept in place for 8 weeks. If there is an RL K-wire, it is left for 2 weeks. K-wires are then placed outside the skin (
Methods of internal fixation have evolved over time. Since the introduction of the Herbert screw, which provides compression force and rigidity at the nonunion site, its success has resulted in many further developments of headless screws, which have compressive abilities and been widely used [
Postoperatively, in case of stable nonunion without SL instability, the wrist is immobilized with a below elbow thumb spica splint. In contrast, in case of unstable nonunion, the wrist is immobilized with an above elbow thumb spica splint for 2 weeks for the protection of RL pinning which was removed after 2 weeks, after which the below elbow thumb spica cast is applied for 8 weeks. Plain radiographs are taken every week until bone union is achieved; however, a computed tomography (CT) scan is taken to confirm the bone union because CT scan is a much more reliable tool than plain radiographs in the evaluation of scaphoid union and deformity [
Waist nonunion is the most common site. Except for cases that are diagnosed early, the gaps are usually large and DISI deformity is common. Moreover, SNAC changes can arise early in the waist nonunion. Given the large defect, significant volumes of cancellous bone graft are required for firm and packed bone graft, and such large volumes can increase the operation time. However, since the capsules and ligament are usually intact in the waist nonunion, the grafted bone is less likely to escape. Bone union was achieved in 35 of 36 nonunion patients. In fifteen patients with SNAC stage I, satisfactory outcomes were achieved both clinically and radiologically with the mean SL angle significant improved from an average 66°±7.9° preoperatively to 50.4°±7.5° at the final follow-up (p=0.001) (
Slade and Gillon [
Kim et al. [
Kang et al. [
Oh et al. [
Several circumstances precluded the use of arthroscopic bone grafting for scaphoid nonunion. First, a surgeon should not attempt using this technique if he/she lacks experience in wrist arthroscopy and arthroscopic anatomy. When we first attempted this operation, we could not find the nonunion site. We then operated using an open technique. Therefore, sufficient wrist arthroscopy experience is extremely important before attempting this operation. Second, we consider the salvage procedure as more effective for severe SNAC and severely destructed wrist joint combined with avascular nonunion; having non-reconstructable fragmented proximal pole than arthroscopic bone grafting. Third, significant arthrofibrosis of the wrist joint causes difficulty in arthroscopic bone grafting. An arthroscopic bone grafting for scaphoid nonunion and delayed union should be performed, with the exception of the above-mentioned limitations.
Arthroscopic bone grafting and percutaneous K-wires fixation seem to be an effective treatment method for patients with scaphoid nonunion. It can provide comprehensive assessment of the fracture status and combined injuries at the time of arthroscopic treatment. This technique can preserve the biology of scaphoid fragments which may promote the bone union.
The authors have nothing to disclose.
The appearance of scaphoid from the mid-carpal joint (A, plain radiographs; B, cadaveric specimen) shows gentle curvature of the waist and the proximal portion that allows fairly stable platform for the surgeon.
Basic instrumentation. (A) 2.5 mm and 1.9 mm video arthroscope, (B) 2.0 mm and 2.9 mm shavers, 3.0 mm burr and radiofrequency probe for surgical instrument. (C) Two custom-made cannulas (3.8 mm and 3.0 mm) and 2 custom-made trocars (3.2 mm and 2.7 mm) for percutaneous bone grafting.
Arthroscopic portals marked in the radio-carpal and mid-carpal joints. MCU, mid-carpal ulnar; MCR, mid-carpal radial; ACC, accessory portal.
A 46-year-old male patient with nonunion of the left scaphoid fracture. Preoperative left wrist plain scaphoid. (A) A view showing nonunion at the waist of the scaphoid. (B) Same patient’s left wrist, mid-carpal arthroscopy image of scaphoid nonunion site shows large gap and sclerotic margins of both fragments. P, proximal fragment; D, distal fragment; MCR, mid-carpal radial.
Left wrist, mid-carpal arthroscopy images of nonunion site of 2 patients after debridement. (A) Showing punctate bleeding from the proximal and distal fragments. (B) Showing no punctate bleeding from the proximal fragment. P, proximal fragment; D, distal fragment; MCR, mid-carpal radial; MCU, mid-carpal ulnar.
After preparing the bone graft, we reduce the scaphoid with traction, gentle passive ulnar deviation, hypersupination and extension of the wrist with a surgical towel placed under the forearm and a 1.2 mm Kirschner-wire is inserted percutaneously from the tubercle of the scaphoid to the proximal pole for provisional scaphoid fixation.
(A) In the presence of a dorsal intercalated segmental instability deformity and extended lunate, the wrist is first flexed to realign the extended lunate with the radius for deformity correction. (B) The radio-lunate joint is then transfixed with a percutaneous 1.2-mm Kirschner-wire inserted from the dorsal distal radius. (C) We then percutaneously fix the scaphoid with a 1.2-mm Kirschner-wire.
(A) Cancellous bone graft is harvested from the iliac crest. (B) The bone graft is then cut into small chips using scissors.
(A) Left wrist, mid-carpal arthroscopy images of percutaneous autogenous iliac cancellous bone grafting at the nonunion site using cannula and trocar. (B) Same patient’s left wrist, mid-carpal arthroscopy image showing finished bone graft to the nonunion site percutaneously using cannula and trocar. MCR, mid-carpal radial; MCU, mid-carpal ulnar.
Immediate postoperative plain scaphoid radiographs of stable nonunion (A) and unstable nonunion (B) show internal fixation with Kirschner-wires and grafted bone at the nonunion site.
Postoperative 49 months after follow-up plain left wrist scaphoid radiograph shows complete bony union.
The mean scapho-lunate angle in 15 scaphoid nonunion advanced collapse patients shows significant improvement from an average 66°±7.9° preoperatively (A) to 50.4°±7.5° at the final follow-up (B).