SCAPHOID (NAVICULAR)

FRACTUREBy

Craig Coldwell

August 31, 2010

THE SCAPHOID BONE: The scaphoid bone (also called the

navicular bone) is one of eight carpal (wrist) bones. These small bones allow complex, yet delicate movements of the hand. The carpal bones fit between the forearm and hand bones. The scaphoid sits below the thumb, and is shaped something like a kidney bean.

BLOOD FLOW TO THE SCAPHOID: The interesting thing about the scaphoid bone is

that is has a retrograde blood supply. This means that the blood flow comes from a small vessel that enters the most distant part of the bone and flows back through the bone to give nutrition to the bone cells.

The pattern of blood supply in the scaphoid presents a problem when you sustain a scaphoid fracture. Because of the tenuous blood supply, a scaphoid fracture can sever this blood flow and stop the delivery of necessary oxygen and nutrients to the bone cells. When this occurs, healing can be slow, and the scaphoid fracture may not heal at all.

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SYMPTOMS OF A SCAPHOID FRACTURE: The symptoms of a scaphoid fracture are pain on the

thumb side of the wrist, swelling in that area, and difficulty gripping objects. Many patients are diagnosed with a wrist sprain, when in actuality they have a broken scaphoid bone. The diagnosis is difficult because x-rays taken right after the injury may show no abnormality. A scaphoid fracture that is not displaced may only show up on x-ray after healing has begun, which can be one to two weeks after the injury. Because of this, it is not uncommon to treat a wrist injury with immobilization (as though it were a scaphoid fracture) for a week or two and then repeat x-rays to see if the bone is broken. An MRI or bone scan is also a possible means to diagnose this injury, but usually not needed.

PROBLEMS WITH SCAPHOID FRACTURE HEALING: When a scaphoid fracture heals slowly

(delayed union), or does not heal at all (non-union), the injury may remain painful, and deformity and arthritis of the bone may result. The risk of developing a non-union of the scaphoid depends most importantly on the location of the fracture in the bone. Other factors that can contribute to non-union are smoking, certain medications, and infections.

TREATMENT OF SCAPHOID FRACTURES: There are two general approaches for

treatment of a scaphoid fracture. Often, orthopedists will initially treat the injury in a cast to see if the fracture heals in a timely manner. So long as the scaphoid fracture is not badly displaced (out of position), this is an excellent approach. By obtaining repeat x-rays over several weeks and months, your doctor can look for signs of healing. Healing of this fracture usually takes 10 to 12 weeks. If it does not heal, surgery can be considered.

TREATMENT OF SCAPHOID FRACTURES: If the scaphoid fracture is displaced, the risk of

nonunion is higher, and your doctor may recommend initial surgery to reposition the bones, and fix them into place. Or if the fracture does not heal with cast treatment (immobilization), surgery will be recommended. The surgery involves using either a screw or small pins to hold the bone together in the proper position. A bone graft may also be used to promote healing at the scaphoid fracture site. The surgical incision will be between two and five centimeters, depending on the dissection necessary to properly position the fracture and place bone graft (if needed). After surgery, a cast is used to immobilize the scaphoid bone and allow for healing.

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OUTCOME STUDY Journal of Bone and Joint Surgery -

British Volume, Vol 63-B, Issue 2, 225-230Copyright © 1981 by British Editorial Society of Bone and Joint Surgery

Articles The fractured carpal scaphoid.

Natural history and factors influencing outcome

IJ Leslie and RA Dickson

OUTCOME STUDY The scaphoid fracture is commonest in young

men in the age group 15 to 29 years, who have the highest incidence of non-union, take the longest time to unite, lose more time from work, and spend the longest time as outpatients.

A union rate of 95 per cent can be achieved using standard simple treatment.

All but a few fractures are visible on the first radiograph, and failure of visualisation at this stage is not associated with a bad outcome. The postero-anterior and semipronated views are the most important to scrutinise.

CONT’D Crank-handle injuries have a particularly

bad prognosis when they produce a transverse fracture of the waist of the scaphoid.

Poor prognostic factors are displacement during treatment, the fracture line becoming increasingly more obvious, and the presence of early cystic change.

The severity of trauma is an important factor to elicit from the history.

OUTCOME STUDY Scaphoid non-union: Factors affecting the

functional outcome of open reduction and wedge grafting with herbert screw fixation

R. Nakamura MD1, E. Horii, K. Watanabe, K. Tsunoda and T. Miura

From the Division of Hand Surgery, Department of Orthopaedic Surgery, Nagoya University School of Medicine, Japan

Accepted 9 June 1992.  Available online 15 April 2005.

CONT’D Abstract 50 patients with scaphoid non-union were treated by

open reduction, anterior wedge bone grafting and internal fixation using the Herbert screw. Intra-operative image intensifier control enabled us to insert the screw into the scaphoid accurately. An excellent or good functional outcome was less likely when more than 5 years had elapsed since injury, the non-union was in the proximal third, when sclerosis of the proximal fragment was present, and when reduction of carpal and scaphoid deformity was unsatisfactory. These four factors are believed to be the primary determinants affecting the functional results of the surgical treatment of scaphoid non-union, even when bony union is achieved.

OUTCOME STUDY Treatment of scaphoid nonunion with casting

and pulsed electromagnetic fields: A study continuation

Brian D. Adams MD, a, b, Gary K. Frykman MDa, b and Julio Taleisnik MDa, b

aDepartment of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vt., USA

bDepartment of Orthopedic Surgery, Loma Linda University School of Medicine, Loma Linda, Calif., USA

Received 31 May 1991;  accepted 20 January 1992.  Available online 4 December 2007.

CONT’D Abstract This article presents a continuation of a study of the

treatment of scaphoid nonunion with pulsed electromagnetic fields (PEMF) and cast immobilization. Fifty-four patients were reviewed. The overall success rate for healing has decreased since the previous review from 80% to 69%. Proximal pole fractures healed in 50%. Success in nonunions with associated radiographic evidence of avascular necrosis decreased from 89% to 73%. Although we believe that the indications for use of PEMF have not changed significantly, this study suggests that a successful outcome with PEMF and casting is less likely than previously reported. We believe that until additional clinical studies have further defined the indications, treatment protocol, and efficacy of this method PEMF treatment should be a secondary alternative to bone-grafting procedures.

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