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.     

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.

Size and stabilization of the dorsoulnar fragment in AO C3-type distal radius fractures

IntroductionVolar locking plate (VLP) fixation has become the gold-standard treatment for distal radius fractures (DRFs). Especially, internal fixation of the volar lunate facet fragment is essential for the treatment of AO C3-type DRFs. On the other hand, the necessity of the fixation of the dorsal lunate facet fragment (dorsoulnar fragment) remains unclear. The purpose of the present study was to measure three-dimensionally the size of the dorsoulnar fragments in AO C3-type DRFs using computed tomography (CT) images in detail, and to reveal relationships of the size and stabilization of the dorsoulnar fragment with postoperative fracture displacement after VLP fixation.Materials and methodsWe retrospectively reviewed the 101 consecutive Japanese patients who underwent surgical treatment for AO C3-type distal radius fractures. If patient had dorsoulnar fragment, the three-dimensional size of this fragment and the occupying ratio to the radiocarpal joint (RCJ) and the distal radioulnar joint (DRUJ) were anatomically evaluated using the preoperative CT images. In addition, we investigated the relationship of the size and stabilization of the dorsoulnar fragment with fracture displacement after VLP fixation. We statistically compared the size parameters and occupying ratio of the dorsoulnar fragment between the displaced group and the stable groups using a two-tailed t-test. We also statistically compared the numbers of screws inserted into the dorsoulnar fragments between the displaced and stable groups using a chi-square test.ResultsThe mean dorsoulnar fragment size was 9.4 mm × 7.9 mm × 11.0 mm and the occupying ratio to the DRUJ and RCJ was 50% and 10%, respectively. The number of patients treated with volar locking plate fixation was 77, of which 12 patients had postoperative displacements. Although the size of the dorsoulnar fragment was not associated with postoperative displacement, stabilization following screw insertion into the dorsoulnar fragment was significantly associated with displacement.ConclusionStabilization of the dorsoulnar fragment with at least one screw of the volar locking plate was necessary to prevent postoperative fracture displacement regardless of dorsoulnar fragment size in AO C3-type distal radius fractures.     

Kinematics of the midcarpal and radiocarpal joint in flexion and extension: an in vitro study

PURPOSE: To apply carpal kinematic analysis using noninvasive medical imaging to investigate the midcarpal and radiocarpal contributions to wrist flexion and extension in a quasidynamic in vitro model. METHODS: Eight fresh-frozen cadaver wrists were scanned with computed tomography in neutral, full flexion, and full extension. Body-mass-based local coordinate systems were used to track motion of the capitate, lunate, and scaphoid with the radius as a fixed reference. Helical axis motion parameters and Euler angles were calculated for flexion and extension. RESULTS: Minimal out-of-plane carpal motion was noted with the exception of small amounts of ulnar deviation and supination in flexion. Overall wrist flexion was 68 degrees +/- 12 degrees and extension was 50 degrees +/- 12 degrees. In flexion, 75% of wrist motion occurred at the radioscaphoid joint, and 50% occurred at the radiolunate joint. In extension, 92% of wrist motion occurred at the radioscaphoid joint, and 52% occurred at the radiolunate joint. Midcarpal flexion/extension between the capitate and scaphoid was 0 degrees +/- 5 degrees in extension and 10 degrees +/- 13 degrees in flexion. Midcarpal flexion/extension between the capitate and lunate was larger, with 15 degrees +/- 11 degrees in extension and 22 degrees +/- 19 degrees in flexion. CONCLUSIONS: The capitate and scaphoid tend to move together. This results in greater flexion/extension for the scaphoid than the lunate at the radiocarpal joint. The lunate has greater midcarpal motion between it and the capitate than the scaphoid does with the capitate. The engagement between the scaphoid and capitate is particularly evident during wrist extension. Out-of-plane motion was primarily ulnar deviation at the radiocarpal joint during flexion. These results are clinically useful in understanding the consequences of isolated fusions in the treatment of wrist instability.     

Patterns of carpal deformity in scaphoid nonunion: a 3-dimensional and quantitative analysis

PURPOSE: To clarify quantitatively the 3-dimensional deformity of the carpus in scaphoid nonunion on the basis of fracture location. METHODS: Three-dimensional computed tomography was used to examine 20 patients with scaphoid nonunion. Displacements of the distal and proximal fragments of the scaphoid, lunate, triquetrum, and capitate were visualized and quantified using a 3-dimensional image-matching technology. Cases were categorized as distal fracture (16 cases) or proximal fracture (4 cases) based on the location of the fracture line relative to the dorsal apex of the scaphoid ridge where the dorsal scapholunate interosseous ligament is attached. RESULTS: The displayed distal scaphoid fractures showed that the proximal fragment of the scaphoid, lunate, and triquetrum rotated into extension and supination. The distal fragment of the scaphoid and capitate translated dorsally without notable rotation. The deformity in proximal fractures was less remarkable than that in distal fractures. Most distal scaphoid nonunions had dorsal intercalated segment instability deformity patterns, whereas a dorsal intercalated segment instability occurred in only 1 case of a proximal fracture. CONCLUSIONS: Whether the fracture line passes distal or proximal to the dorsal apex of the scaphoid determines the subsequent carpal deformity. Dorsal translation of the distal fragment might be one of the factors in the development of degenerative change at the radial styloid.     

Kinematics of the midcarpal and radiocarpal joints in radioulnar deviation: an in vitro study

PURPOSE: Carpal kinematics have been studied widely yet remain difficult to understand fully. The noninvasive measurement of carpal kinematics through medical imaging has become popular. Studies have shown that with radial deviation the scaphoid and lunate flex whereas the capitate moves radiodorsally relative to the lunate. This study investigated the midcarpal and radiocarpal contributions to radial and ulnar deviation of the wrist. This was accomplished through noninvasive characterization of the scaphoid, lunate, and capitate using 3-dimensional medical imaging of the wrist in radial and ulnar deviation. METHODS: Eight fresh-frozen and thawed cadaveric wrists were used in an experimental set-up that positioned the wrist through spring-scale actuation of the 4 wrist flexor and extensor tendon groups. The wrists were scanned by computed tomography in neutral and full radial and ulnar deviation. Body mass-based local coordinate systems were used to track the motion of the capitate, lunate, and scaphoid with the radius as a fixed reference. Helical axis motion and Euler angles were calculated from neutral to radial and ulnar deviation for the capitate relative to the radius, lunate, and scaphoid and for the lunate and scaphoid relative to the radius. RESULTS: The capitate, scaphoid, and lunate moved in a characteristic manner relative to the radius and to one another. Radial and ulnar deviation occurred primarily in the midcarpal joint. Midcarpal motion accounted for 60% of radial deviation and 86% of ulnar deviation. In radial deviation the proximal row flexed and the capitate extended; the converse was true in ulnar deviation. CONCLUSIONS: Radioulnar deviation (in-plane motion) occurred mostly through the midcarpal joint, with a lesser contribution from the radiocarpal joint. The results of our study agree with previous investigations that found the scaphoid and lunate flex in radial deviation (out-of-plane motion) relative to the radius whereas the capitate extends (out-of-plane motion) relative to the scaphoid/lunate (with the converse occurring in ulnar deviation). Our study shows how these out-of-plane motions combine to produce in-plane wrist radioulnar deviation. The use of 3-dimensional visualization greatly aids in the understanding of these motions. The results of our study may be useful clinically in understanding the consequences of isolated midcarpal fusions in the treatment of wrist instability.     

The triple-injection wrist arthrogram

The last 100 patients to have wrist arthrography at our institution had, in addition to the standard radiocarpal joint injection, injections into the distal radioulnar joint and midcarpal joint. Seventy-seven of the 100 patients had abnormal arthrograms. In 29 cases abnormalities not identified by the radiocarpal joint injection were demonstrated either by the distal radioulnar joint or the midcarpal joint injection. In 38 patients abnormalities shown by radiocarpal joint injection were not demonstrable by the other two injections. Seven detachments of the triangular fibrocartilage complex from the ulnar styloid could be demonstrated only by the distal radioulnar joint injection. The midcarpal joint injection was far more useful than the radiocarpal joint injection in the evaluation of radiocarpal joint-midcarpal joint communications. All three injections appear to be necessary for a complete arthrographic evaluation.     

带筋膜血管蒂桡骨骨膜骨瓣移植治疗陈旧性舟骨骨折

目的探讨带筋膜桡动脉茎突返支蒂桡骨骨膜骨瓣移植治疗陈旧性腕舟状骨骨折的临床疗效。方法切开复位，采取桡骨茎突切除加用带筋膜血管蒂骨膜骨瓣移植治疗陈旧性腕舟骨骨折15例，术后进行5～16个月随访。结果临床用骨瓣治疗舟骨骨折15例，骨瓣血供丰富，术后10～12周愈合，腕关节功能恢复正常。结论带筋膜血管蒂桡骨骨膜骨瓣是移植治疗陈旧性腕舟骨骨折及骨不连的一种可靠的方法。     

Hypertrophic ulnar styloid nonunions

Eleven patients with chronic pain on the ulnar side of the wrist and roentgenographic evidence of a hypertrophic ulnar styloid nonunion were treated with subperiosteal excision of the nonunion fragment. This procedure relieved the localized pain without changing either radiocarpal or distal radioulnar joint stability.     

Radiocarpal osteoarthritis associated with bilateral bipartite carpal scaphoid bones: a case report

Bipartite carpal scaphoid is a rare congenital anomaly. The authors report on a 56-year-old man who presented with bilateral wrist pain without a history of trauma. X-ray films demonstrated bilateral symmetric bipartition of the scaphoid into a large distal ossicle and a smaller proximal ossicle. There was degenerative change in the articulation between the distal ossicle and the radial styloid. The joint space between the proximal ossicle and the scaphoid fossa was preserved. The absence of periscaphoid degenerative change has been suggested as a criterion for the diagnosis of congenital bipartite scaphoid. This patient fulfilled all other criteria for the diagnosis and the authors suggest that degenerative change developed due to abnormally high contact force between the distal ossicle and the radial styloid. An identical pattern of degenerative change has been observed in long-standing nonunion of the scaphoid, likely due to a similar mechanism. Radiocarpal osteoarthritis can develop in patients with congenital bipartition of the scaphoid and is similar to that observed in long-standing nonunion of the scaphoid.     

Contact pressures in radiocarpal and triquetrohamate joints after vascularized capitate transposition

The vascularized capitate transposition has been designed to treat advanced Kienb?ck disease, in which the necrotic lunate is excised and the vascularized capitate bone graft is proximally shifted into the lunate fossa to reconstruct the radiocarpal joint. Since it notably alters the normal anatomy of the wrist, the anatomical alterations are thought to be responsible for the increased tendency to develop symptomatic arthritis. Clinically, however, more than 1-year follow-up does not show any arthrosis in the reconstructed radiocarpal joint after this procedure. We tied to investigate the reason of no postsurgical arthrosis by documenting the contact pressures in the radiocarpal and triquetrohamate joints in a cadaveric wrist model. The contact pressures were measured by the super low pressure Fuji prescale film in 6 different wrist positions. No statistically significant difference existed in the average contact pressures of the scaphoid fossa, lunate fossa, triangular fibrocartilage, and triquetrohamate articulation in each wrist position between pre- and postsurgically. These results suggest that this procedure does not necessarily result in increased rate of postsurgical 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.     

Simulated scaphoid proximal pole fracture

Five fresh cadaver upper extremities were studied with use of a static positioning frame, pressure-sensitive film, a microcomputer-based videodigitizing system, and a Sun station image analysis system to assess the load bearing characteristics of the scaphoid in the proximal carpal joint. Specimens were studied in their normal condition, after a proximal pole osteotomy of the scaphoid, and after resection of the proximal pole of the scaphoid. The amount of contact area born through the scaphoid fossa was essentially the same whether the scaphoid was intact, or after a simulated scaphoid fracture of its proximal pole, or after resection of the proximal pole. The scaphoid contact area and pressure, although overall relatively constant, was redistributed after osteotomy, resulting in increased contact area under the distal fragment and no change or a slight decrease in the contact area under the proximal fragment of the scaphoid. After resection of the proximal fragment, all scaphoid contact area and pressure was born by the distal scaphoid fragment. The contact area and pressure characteristics of the lunate remained unchanged in all conditions compared with the normal condition. There were no significant changes in the locations of the centroids of the scaphoid segments and the lunate in any of the conditions tested.     

Radioscapholunate arthrodesis

Although RSL fusion is a viable option for isolated radiocarpal arthritis, the enthusiasm for this procedure should be tempered with the reality that kinematics of the wrist is not entirely suited for independent midcarpal flexion and extension [10]. Limited wrist flexion and extension is expected following a successful RSL arthrodesis. The effects of imposed abnormal kinematics are further shown by the high incidence of RSL nonunions, occurrence of scaphoid fractures, and postoperative deterioration of the midcarpal joint [15,22]. In a young patient with posttraumatic arthritis or rheumatoid arthritis limited to the radiocarpal joint, however, RSL arthrodesis remains a viable alternative to complete wrist arthrodesis if the midcarpal joint is normal. Internal fixation with plates and screws and distal scaphoid excision are technical alternatives to consider when an RSL arthrodesis is performed.     

Distal scaphoid excision after radioscaphoid arthrodesis

Radioscaphoid and radioscapholunate arthrodeses are effective surgical procedures for the treatment of nonsalvageable and isolated radiocarpal arthritis. These procedures, however, limit wrist motion significantly as the immobile scaphoid bridges the remaining midcarpal joint. A cadaver study of radioscaphoid arthrodesis followed by distal scaphoid excision was undertaken. Range of motion after radioscaphoid K-wire fixation alone demonstrated a 58% decrease in the preoperative flexion-extension arc to 60 degrees. After distal scaphoid excision (with the radioscaphoid pins still in place) the flexion-extension arc increased to 122 degrees or 86% of the preoperative range of motion; most of the increase in motion occurred at the midcarpal joint. Distal scaphoid excision releases the midcarpal joint following radioscaphoid fixation and results in a significantly greater wrist motion. If the results of this cadaver study are extrapolated to clinical practice the addition of this step to the previously described procedures of radioscaphoid or radioscapholunate arthrodesis addresses their major limitation, restricted motion.     

Severity of scapholunate instability is related to joint anatomy and congruency

PURPOSE: To determine whether the bony architecture of the distal radius and proximal scaphoid have a role in stabilizing the scaphoid, and to determine whether a relationship between the bony geometry measurements and the amount of wrist constraint could be determined. METHODS: Eight cadaver wrists were tested in a wrist joint motion simulator. The level of scapholunate instability after sectioning the scapholunate interosseous, radioscaphocapitate, and the scaphotrapezium ligaments was determined and related to radiographic measurements of volar tilt, lateral tilt (ulnar tilt of the radioscaphoid fossa), the depth of the radioscaphoid fossa, and 6 radii of curvature measurements of the proximal scaphoid and distal radius. The force to dorsally dislocate the scaphoid out of the radioscaphoid fossa was computed. RESULTS: The radioscaphoid fossa and scaphoid curvatures were larger in those wrists that did not show gross instability after ligamentous sectioning in the wrist simulator. Similarly, those wrists with a deeper radioscaphoid fossa and greater volar tilt were also more stable. The force required to dislocate these wrists was greater than in those wrists that showed gross carpal instability. CONCLUSIONS: This study suggests that the bony anatomy of the radius and scaphoid have a role in stabilizing the carpus after ligament injury. The effect of ligament sectioning on producing carpal instability may be moderated by the bone geometry of the radiocarpal joint. This may explain why some people may have a tear of the scapholunate interosseous ligament but not present with clinical symptoms.     

Anatomical study of radiocarpal joint--degenerative change and morphometry]

The present investigator studied following degenerative changes of the articular cartilage of the radiocarpal joint: the ruptures of the scapholunate and the lunotriquetral interosseous ligaments (S-L lig., L-T lig.), the shape of the scaphoid and the lunate fossa of the distal radius. We studied 120 wrist joints from 74 cadaveric specimens (age 20-97, average age 68). The cartilaginous changes were correlated significantly with age (p < 0.01). The cartilaginous changes were most commonly found in the ulnar demarcation of the lunate, next commonly, in the radiodorsal demarcation of the scaphoid fossa, thirdly, in the radiodorsal demarcation of the scaphoid and finally, in the radial demarcation of the scaphoid fossa. Clearly, the cartilaginous changes in the ulnar demarcation of the lunate intensified proportionally as the ulnar variance increased (p < 0.05) and as the radial inclination decreased (p < 0.05). The S-L lig. and the L-T lig. ruptures increased as the age of the specimens increased. The cartilaginous changes of the interosseous ligament rupture group were stronger than those of the non ligament rupture group (p < 0.01). The concavity of the scaphoid fossa in the dorsovolar direction exhibited an S shaped curve, a convexity on the dorsal side and a concavity on the volar side. The other concavities exhibited a smooth concave curve. From these results, it was concluded that the stability of the wrist joint in extention and the cartilaginous changes of the radioscaphoid joint were due to the volar concavity of the scaphoid fossa of the radius.     

Degenerative change in symptomatic scaphoid nonunion

A retrospective radiographic analysis of 64 patients with symptomatic scaphoid nonunions without previous surgical treatment was accomplished. The results showed a high frequency of degenerative changes occurring in a predictable sequence. For nonunions of 4 years duration, 75% of patients had radioscaphoid changes, and for those of 9 years duration 60% of the patients had midcarpal changes. The pattern of arthritis in scaphoid nonunion is that of scapholunate advanced collapse (SLAC) wrist resulting from rotary subluxation of the distal scaphoid fragment. The radius-proximal scaphoid fragment joint and the radiolunate joint were consistently spared from degenerative changes, even with severe arthritis. Instability was progressive and associated with an earlier onset of arthritis. Patients with symptomatic scaphoid nonunions appear to have a significant likelihood of arthritis developing.     

Combined radiocarpal arthrodesis and midcarpal (lunocapitate) arthroplasty for treatment of rheumatoid arthritis of the wrist

Arthroplasties for the wrist with rheumatoid arthritis are usually revised for the articulation between radius and carpus. The midcarpal joint is disregarded although it remains structurally better preserved and is therefore better suited for the preservation of stable motion. When the midcarpal surfaces are satisfactory, a radio-scapho-lunate fusion, accompanied by a midcarpal synovectomy, is an excellent procedure. When the midcarpal surfaces, particularly the head of the capitate, are also destroyed, the tendency has been to either perform a pan-arthrodesis, or to insert a wrist endo-prosthesis. For these severely unstable and destroyed wrists, a stabilization of the radiocarpal joint by arthrodesis, combined with preservation of motion at the midcarpal level by resection of the damaged head of the capitate and its replacement with a small implant has been done. This procedure has allowed all patients to retain a functional range of motion and to experience satisfactory relief of pain.