Scaphoid nonunions: a 3-dimensional analysis of patterns of deformity

We tested the hypothesis that the fracture location of scaphoid nonunions relates to the fracture displacement, development of dorsal intercalated segment instability (DISI) deformity, and changes in the contact area of the bones in the radiocarpal joint. Eleven patients with scaphoid nonunions were examined with 3-dimensional computed tomography and a new method of proximity mapping. Two different patterns of displacement of scaphoid nonunions were demonstrated, 1 volar and 1 dorsal. All patients with a volar pattern scaphoid nonunion had a DISI deformity. Only a few of the patients with a dorsal pattern scaphoid nonunion, mostly in longstanding nonunions, had a DISI deformity. The fracture line was generally distal to the dorsal apex of the ridge of the scaphoid in the volar-type fractures and proximal in the dorsal displaced fractures. The proximity map of the distal fragment of the scaphoid on the radius in the volar type shifts radial compared with normal; in the distal type it shifts dorsal. Neither of the patterns showed any significant changes of the proximity map in the radiocarpal joint at the proximal scaphoid fragment and the lunate. Whether the fracture line passes distal or proximal to the dorsal apex of the ridge of the scaphoid appears to determine the likelihood of subsequent fracture displacement, DISI deformity, and contact area of the bones in the radiocarpal joint.     

Association between lunate morphology and carpal collapse patterns in scaphoid nonunions

PURPOSE: Type I lunates have a single distal facet for articulation with the capitate; type II lunates have an additional (medial) hamate facet on the distal articular surface. We retrospectively reviewed a series of patients with scaphoid nonunions to determine if there was an association between lunate morphology and the degree of carpal instability observed. Association between lunate morphology and the location of the scaphoid fracture (proximal or waist) was also investigated. METHODS: Radiographs were evaluated for 45 patients with established scaphoid nonunions. Lunate morphology, scaphoid fracture location, and radiolunate angle were determined. RESULTS: Type I lunates were present in 21 patients. Of these, 15 were found to have a dorsal intercalated segment instability pattern (radiolunate angle greater than 15 degrees ). By contrast, only 4 of the patients with type II lunates exhibited this pattern of instability. No significant association was found between lunate morphology and the scaphoid fracture location. CONCLUSIONS: Type II lunate morphology is associated with significantly decreased incidence of dorsal intercalated segment instability (DISI) deformity in cases of established scaphoid nonunion (p = .0002). Lunate morphology, however, was not significantly associated with the location of the scaphoid fracture in these cases (p = .19).     

Patterns of bone defect in scaphoid nonunion: a 3-dimensional and quantitative analysis

PURPOSE: To clarify patterns and size of bone defect in scaphoid nonunion in order to facilitate accurate correction of scaphoid deformity. METHODS: Three-dimensional computed tomography was used to examine 24 patients with scaphoid nonunion. Configuration and size of bone defect were quantified and computed on the basis of fracture location. Cases were categorized as distal or proximal based on location of the fracture line relative to the dorsal apex of the scaphoid ridge. RESULTS: Distal scaphoid fractures displayed wedge-shaped bone defects with the base facing volarly. Proximal scaphoid fractures exhibited flat, crescent-shaped defects that presented only around the fracture site. The size of bone defects was significantly greater for distal fractures than for proximal fractures. CONCLUSIONS: Whether the fracture line passes distal or proximal to the dorsal apex of the scaphoid ridge is a crucial factor in the generation of bone defect. A large wedge-shaped bone graft from the volar side is necessary for distal nonunion whereas a small cancellous bone graft from the dorsal side may be preferable for proximal nonunion.     

Three-dimensional analysis of osteophyte formation on distal radius following scaphoid nonunion

Background

The purposes of this study were to quantitatively analyze osteophyte formation of the distal radius following scaphoid nonunion and to investigate how fracture locations relate to osteophyte formation patterns.

Correction of lunate malalignment when bone grafting scaphoid nonunion with humpback deformity: rationale and results of a technique revisited

Patients with scaphoid nonunion with humpback deformity and collapse of the wrist were treated with palmar wedge bone grafting combined with reduction of the lunate to correct the dorsal intercalated segment instability deformity. Union was obtained at an average of 3 months, and patient satisfaction with functional outcome and pain relief was high. Palmar wedge bone grafting combined with correction of lunate malalignment successfully achieved scaphoid union, restored scaphoid length, and avoided the potential complication of scaphoid malunion. This report revisits a technique that facilitates accurate correction of lunate malalignment (dorsal intercalated segment instability) by initial reduction and pin fixation to the radius before insertion of scaphoid bone graft and internal fixation.     

Preliminary lunate reduction and pinning facilitates restoration of carpal height when treating perilunate dislocation, scaphoid fracture and nonunion, and scapholunate dissociation

Carpal collapse potentially accompanies greater and lesser arc perilunate injuries; unstable, acute scaphoid fracture; scaphoid nonunion with humpback deformity; and scapholunate dissociation. When surgical treatment is elected, preliminary reduction of the lunate from extension to neutral--to correct dorsal intercalated segment instability deformity--facilitates restoration of carpal height and decreases the risk of carpal malalignment and scapholunate advanced-collapse arthritis. This simple technique is described.     

The role of the dorsal intercarpal ligament in dynamic and static scapholunate instability

PURPOSE: Scapholunate instability (SLI) is the most common carpal instability. Recent studies have suggested that the dorsal intercarpal (DIC) and the dorsal radiocarpal ligaments play an important role in stabilization of the scaphoid and lunate. Differences between dynamic SLI and static SLI with a dorsal intercalated segment instability (DISI) are clearly described in the clinical literature; however, there has never been a clear explanation of the anatomic differences. This study describes the role of the DIC in the development of dynamic and static SLI with DISI in a cadaver model. METHODS: Five fresh cadavers were studied radiographically and by 3-dimensional digitization. Six increasing stages of instability were developed by sectioning progressively the following structures: the dorsal capsule, the palmar and proximal (membranous) portion of the scapholunate interosseous ligament, the DIC from its insertion on the scaphoid and trapezium, the dorsal scapholunate interosseous ligament from the scaphoid, the DIC ligament from its attachment on the lunate, and the lunotriquetral interosseous ligament. RESULTS: The scaphoid position and the scapholunate gap changed significantly after sectioning the entire scapholunate interosseous ligament and DIC from the scaphoid when a 5-kg load was applied. The lunate position was unchanged in both the loaded and the unloaded conditions. After detaching the DIC from the lunate, both the scaphoid and lunate moved and the scapholunate gap increased significantly in both loaded and unloaded conditions and showed a DISI deformity. CONCLUSIONS: This study describes an anatomic difference between dynamic and static scapholunate instability. Complete disruption of the scapholunate ligament did not result in the development of a static collapse of the lunate. The DIC had an important role in stabilizing the scaphoid and lunate and preventing DISI deformity. This study suggests that in the clinical setting the DIC ligament should be assessed intraoperatively and consideration should be given to repair and/or reconstruction of the DIC ligament attachments to both the scaphoid and the lunate.     

Scaphoid nonunion and distal fragment resection: analysis with three-dimensional rigid body spring model

Background  Distal fragment resection is one of the salvage procedures for scaphoid nonunion with osteoarthritis. Despite being reported as a simple procedure with favorable midterm outcomes, further arthritic changes remain a concern in the long term. Scaphoid waist fracture is classified into volar or dorsal types according to the displacement pattern, but the indications for distal fragment resection have never been discussed for these fracture types. Method  We reconstructed a normal wrist model from computed tomography images and performed theoretical analysis utilizing a three-dimensional rigid body spring model. Two types of scaphoid fracture nonunion followed by distal fragment resection were simulated. Results  With volar-type nonunion, the force transmission ratio of the radiolunate joint increased, and the pressure concentration was observed in the dorsal part of the scaphoid fossa and volar part of the lunate fossa of the radius; no deterioration was seen in the midcarpal joint. In the distal fragment resection simulation for volar-type nonunion, pressure concentrations of the radiocarpal joint resolved. With dorsal-type nonunion, force transmission ratio in the radiocarpal joint resembled that of the normal joint model. Pressure concentrations were observed in the dorsoulnar part of the scaphoid fossa and radial styloid. The pressure concentration in the dorsoulnar part of the scaphoid fossa disappeared in the resection model, whereas the concentration in the radial styloid remained. In the midcarpal joint, pressure was concentrated around the capitate head in the nonunion model and became aggravated in the resection model. Conclusions  With volar-type scaphoid nonunion, distal fragment resection seems to represent a reasonable treatment option. With dorsal-type nonunion, however, pressure concentration around the capitate head was aggravated with the simulated distal fragment resection, indicating a potential risk of worsening any preexisting lunocapitate arthritis.     

Resection of the distal pole of the scaphoid for scaphoid nonunion with radioscaphoid and intercarpal arthritis

PURPOSE: The treatment of scaphoid nonunion with degenerative arthritis poses a clinical problem that is particularly challenging in cases of associated dorsal intercalated segmental instability collapse, radiocarpal and intercarpal degenerative changes, and poor scaphoid bone quality. The purpose of this study was to report our clinical experience performing a distal scaphoid resection for symptomatic scaphoid nonunion in patients with either radioscaphoid or intercarpal arthritis who have had multiple surgeries. METHODS: Nine patients with recalcitrant scaphoid nonunion and associated degenerative arthritis treated by resection of the distal scaphoid fragment were evaluated both clinically and radiographically. Eight patients were male and one patient was female; the average follow-up period was 28.6 months (range, 12-52 mo). RESULTS: Seven patients reported pain with daily use and the remaining 2 patients reported mild pain with light work before surgery, whereas after surgery 4 of the 9 patients had no wrist pain and the remaining 5 patients had only mild pain with strenuous activity. The wrist range of motion improved from 70 degrees (51.4% of the opposite wrist) to 140 degrees (94% of the opposite wrist) and grip strength improved from 18 kg (40% of the opposite wrist) to 30 kg (77% of the opposite wrist). Clinical results were excellent in 6 patients and good in 3 patients based on a modified Mayo wrist-scoring chart. Radiographically neither additional degeneration nor progress of degenerative changes was noted after surgery in 8 patients. Newly developed degenerative arthritis occurred at the proximal scapholunate capitate articulation in the remaining patient who has a type II lunate, which had a facet (medial facet) articulation with the hamate. CONCLUSIONS: The results of this study showed that distal scaphoid resection produces a satisfactory clinical outcome, requires only a short period of immobilization, and should be considered one of the surgical options for long-standing scaphoid nonunion with either radioscaphoid or intercarpal degenerative arthritis. Nevertheless care must be taken in performing this procedure on patients whose preoperative radiograph show a type II lunate.     

Proximal row carpectomy with capitate osteochondral autograft transplantation

Proximal row carpectomy (PRC) is an effective treatment option for degenerative or posttraumatic osteoarthritis of the wrist in conditions such as scapholunate advanced collapse, scaphoid nonunion advanced collapse, Kienbock disease, and chronic fracture dislocations of the carpus. PRC involves excision of the scaphoid, lunate, and triquetrum, and relies on the articulation of the remaining capitate from the distal row to articulate with the lunate fossa. PRC offers the potential advantage of greater range of motion, technical ease, and decreased immobilization, and eliminates specific complications found with other motion-preserving procedures such as nonunion, hardware irritation, and impingement. An established relative contraindication for PRC is the presence of advanced capitolunate arthritis. Many authors have offered modifications of the traditional PRC procedure to account for the presence of capitate arthritis. A PRC technique utilizing an osteochondral autograft, from the carpal bank of excised bones, for transfer to the capitate defect is described.     

Kinematics of the ulnar carpus related to the volar intercalated segment instability pattern

Anatomic dissections were done on 18 fresh and 4 preserved cadaver upper extremities to study the pathology of the carpal kinetics and to define the ligaments involved in the volar intercalated segment instability pattern. In a normal wrist, the scaphoid, lunate, and triquetrum all rotate so that their distal surfaces tilt palmarward with radial deviation. With ulnar deviation, all three carpal bones rotate dorsally. In the volar intercalated segment instability pattern, the lunate remains tilted volarly instead of rotating dorsally with ulnar deviation. In this study changes in carpal motion were observed after serially sectioning the ligaments supporting the ulnar carpus before and after loads were applied to the wrist to simulate the dynamic conditions of the wrist. The ligaments were then repaired to help identify which repairs restored normal carpal motion with radial and ulnar deviation with and without axial loads. In these anatomic studies the volar intercalated segment instability pattern occurred when there was instability between both hamate and triquetrum and between the lunate and triquetrum. The main ligaments involved in this instability appeared to be the ulnar half of the volar arcuate ligament and the luno-triquetral ligament as division of these ligaments, particularly under axial loads, produced the most significant change in lunate rotation (p less than 0.05). Similarly repair of these two ligaments produced the most significant correction of lunate position particularly with maintenance of dorsal rotation of the lunate during ulnar deviation under axial loads (p less than 0.01).     

The relationship between the site of nonunion of the scaphoid and scaphoid nonunion advanced collapse (SNAC).

We studied retrospectively the radiographs of 33 patients with late symptoms after scaphoid nonunion in an attempt to relate the incidence of scaphoid nonunion advanced collapse (SNAC) to the level of the original fracture. We found differing patterns for nonunion at the proximal, middle and distal thirds. The mean intervals between fracture and complaint were 20.9, 6.7 and 12.6 years and obvious degenerative changes occurred in 85.7%, 40.0% and 33.3%, for the six proximal-, eight middle- and two distal-third nonunions, respectively. Nonunion at the proximal and middle thirds showed the first degenerative changes at the radioscaphoid joint, and this was followed by narrowing of the scaphocapitate and then the lunocapitate joints. In our two nonunions of the distal third degenerative changes were seen only at the lunocapitate joint. Most patients with SNAC and nonunion of the middle or distal third showed dorsal intercalated instability; few patients with nonunion of the proximal third developed this deformity. We discuss the initial management of nonunion of the scaphoid at different levels in the light of our findings, and make recommendations.     

Difficult wrist fractures. Perilunate fracture-dislocations of the wrist

Perilunate dislocations of the wrist have a common pathway of disruption that occurs from extensive dorsiflexion injuries. Open reduction and internal fixation of these injuries is required to provide accurate alignment and the option for ligament repair. Both dorsal and palmar surgical incisions may be indicated. Associated injuries to the median nerve must be recognized. Treatment includes scaphoid and radial styloid stabilization with multiple K-wires or internal compression screw (Herbert or Association for the Study of Internal Fixation [ASIF] screws). In these injuries, the lunate must be reduced first and stabilized. The scaphoid proximal segment follows the lunate unless the scapholunate (SL) ligament is torn. The distal scaphoid fragment, capitate, and triquetrum are reduced and aligned with the lunate and need to be held with K-wires. Ligament repair and augmentation may be necessary at both scapholunate and lunotriquetal areas if there has been serious ligament injury. Palmar ligament repair is often required, and we recommend a palmar exploration in most patients along with release of the median nerve. Surgical treatment results of perilunate fracture-dislocations of the wrist appear better than conservative treatment methods, but complications following both indicate the need for improved internal fixation and fracture-dislocation realignment. These fractures are a real challenge to the treating surgeon who must use patience, precise surgical techniques, and careful roentgenographic study (including tomograms and traction views) to assure the best result.     

Three-corner wrist fusion using memory staples

Scapholunate dissociation with advanced collapse (SLAC), scaphoid nonunion advanced collapse (SNAC), and lunotriquetral advanced collapse (LTAC) of the carpus are challenging problems. Various treatment options have been described. We describe a technique of 3-corner wrist fusion, using memory staples. The scaphoid and triquetrum are resected, and the capitate is fused to the lunate. Articular cartilage is removed from the capitolunate joint, and the bones are shaped to conforming surfaces. Bone graft from the resected triquetrum and scaphoid is used to increase fusion rate and a dynamic compressive fixation force is applied due to the unique properties of the memory staples. The main advantages of this procedure include the following: retained anatomical articulation between the lunate and the lunate fossa on the radius, improved ulnar deviation due to the resection of the triquetrum, and an excellent fusion rate between the lunate and capitate due to the dynamic fixation, the conforming surfaces, and the use of autologous bone graft.     

Scaphoid nonunion treated with vascular bone grafts pedicled on the dorsal supra-retinacular artery of the distal radius

BACKGROUND: Nonunion and avascular necrosis (AVN) are frequent complications of scaphoid fractures. We describe the operative technique and long-term results of treatment with pedicle vascularized bone grafts (VBGs) of the distal radius in patients with scaphoid fractures in whom nonunion and AVN developed. METHODS: During a 4-year period (1997-2000), VBGs pedicled on either the first and second or second and third compartments of the supraretinacular artery of the distal radius were in our hospital used to treat 11 patients with symptomatic scaphoid nonunion involving AVN of the proximal fragment (one with perilunate transscaphoid fracture dislocation and 10 with displaced scaphoid fractures with nonunion). Nine of these 11 patients received fixation with divergent K-wires fixation and two received Herbert screws fixation. RESULTS: Osseous union was achieved in all 11 patients treated with VBGs within an average period of 13 weeks. Functional results of treatment, which were measured using the modified Mayo Wrist Score, were encouraging in all patients in this series (four excellent, six good, and one fair). The deformity of ununited scaphoid was well corrected. CONCLUSIONS: The index study suggests that this treatment can be used not only to revascularize necrotic scaphoid, but also to correct humpback deformity and the resulting carpal instability.     

Intercarpal arthrodesis for static and dynamic volar intercalated segment instability

Since 1982 seven patients with volar intercalary segment instability (VISI) have been operated on at the Massachusetts General Hospital. All had preoperative wrist pain and described a painful "clunk" with ulnar deviation. In each case there was palpable evidence of instability when the wrist was deviated ulnarly that produced a "buckling" sensation as the distal and proximal rows rotated with ulnar deviation. Arthrograms in six patients and a cineradiography in one patient confirmed that this buckling correlated with volar rotation of the lunate and triquetrum and dorsal rotation of the capitate and hamate. All the patients had some type of intercarpal arthrodesis including four capitate-lunate-triquetrum hamate (CLTH), one lunate-triquetrum (LT), one lunate-triquetrum-hamate (LTH), and one triquetrum-hamate (TH). Surgical findings included the position of the lunate that had rotated on the capitate so that it was tilting volarly and the major ligament instability was between the proximal and distal rows although ligament tears were also present between lunate and triquetrum. Arthrodesis of the proximal and distal rows provided relief of wrist pain in five of six patients. The one patient with the arthrodesis limited to the proximal row had a poor result. Of the five successful cases, the postoperative range of wrist motion was 81 degrees of extension/flexion arc (63% of the normal contralateral) and 35 degrees of radial and ulnar deviation arc (57% of the normal contralateral wrist). The grip strength postoperatively averaged 58 pounds (74% of the normal contralateral side).     

Radiographic clues for determining carpal instability and treatment protocol for scaphoid fractures

The magnitude of carpal instability following scaphoid fracture is closely related to the fracture location. Middle-third fractures of the scaphoid are classified into B1 (distal oblique fractures) and B2 (complete waist fractures). Deciding preoperatively whether a fracture is B1 or B2 is clinically important, because several studies have revealed that B1 is more stable than B2. Dorsal intercalated segment instability deformity often develops in B2, creating a large, wedge-shaped bone defect, while minimal humpback deformity develops in B1, and the bone defect is much smaller, even after long-standing nonunions. However, determination of the fracture types using X-rays may be less accurate than using three dimensional computed tomography. This article suggests two radiographic clues for estimation of post-fracture carpal instability along with a treatment protocol for each fracture type.     

Isolated fracture-dislocation of the scaphoid’s proximal pole treated by scaphoid internal fixation and scapho-lunate ligament reconstruction

We present a case of irreducible palmar dislocation of the proximal fragment of a scaphoid fracture without carpal dislocation. We observed this lesion 2 days after the injury and we immediately operated the patient with a combined volar and dorsal access: using the Henry access we reduced the fracture and we inserted a cannulated screw to synthesize the scaphoid, using the dorsal access we repaired the complete rupture of the scapho-lunate ligament using a mini anchor. Stabilization among scaphoid, lunate and capitate was performed using Kirschner wires. X-ray showed fracture healing after 90 days. No clinical or radiographic evidence of carpal instability was revealed, on standard X-rays or on dynamic evaluations. No sign of avascular necrosis or degenerative arthritis was observed after 9 months.     

部分腕骨融合术或切除术对腕关节运动影响的实验研究

目的 研究临床常用的部分腕骨融合术或切除术对腕关节运动的影响程度。方法 将１２侧新鲜上肢处理后,固定于特制的测试架上,在腕背部打入２根或多根克氏针,作舟头骨、舟大小多角骨、舟月骨、月三解骨、桡月骨、ｆｏｕｒ ｃｏｒｎｅｒ、头月骨融合术、舟骨切除＋ｆｏｕｒ ｃｏｒｎｅｒ、舟骨切除＋头月融合术。观测腕关节正常运动活动范围,及作上述不同部分腕骨融合术后腕关节屈曲、伸腕、尺偏、桡偏度数。结果 桡舟月骨融合