Management of the scaphoid during four-corner fusion-a cadaveric study

The Biomechanical Effects of Simulated Radioscapholunate Fusion With Distal Scaphoidectomy, 4-Corner Fusion With Complete Scaphoidectomy, and Proximal Row Carpectomy Compared to the Native Wrist

PURPOSE

To determine the effect of simulated radioscapholunate fusion with distal scaphoid excision (RSLF+DSE), 4-corner fusion with scaphoidectomy (4-CF), and proximal row carpectomy (PRC) on the wrist's range of motion (ROM), contact pressure, and contact force in a cadaveric model.

METHODS

Ten freshly frozen cadaveric wrists were tested under 4 sequential conditions: native wrist, RSLF+DSE, 4-CF, and PRC. The simulated fusions were performed using two 1.6-mm Kirschner wires. The ROM in the flexion-extension and radioulnar deviation planes was evaluated. Contact area, contact pressure, and contact force were measured at the scaphocapitolunate joint for the RSLF+DSE simulation and radiocarpal joint for the 4-CF and PRC simulations. Mechanical testing was performed using a 35-N uniaxial load and pressure-sensitive film.

RESULTS

The RSLF+DSE and 4-CF groups had a decreased wrist arc ROM compared with the native wrist. The PRC group had a greater wrist arc ROM compared with the RSLF+DSE and 4-CF groups, but compared to the native wrist, it demonstrated a mildly decreased wrist arc ROM. The carpal pressure and contact force were significantly increased in the RSLF+DSE, 4-CF, and PRC groups compared with those in the native wrist. The RSLF+DSE group had the smallest increase in the carpal pressure and contact force, whereas the PRC group had the greatest increase.

CONCLUSIONS

Our study validates previous findings that PRC is motion-conserving but has the greatest contact force, whereas RSLF-DSE and 4-CF may cause a decrease in the ROM but have lower contact forces.

CLINICAL RELEVANCE

Understanding the underlying native wrist biomechanics and alterations following different surgical treatments may assist hand surgeons in their clinical decision making for the treatment of stage II scapholunate advanced collapse.

The Use of Contact Biomechanics to Study the Intact, Proximal Row Carpectomy and Scaphoid Excision, Four Bone Fusion Wrist

The study of contact biomechanics of the wrist is a challenge. This is partly due to the relatively small size of the joint as well as the lack of space in the radiocarpal joint which makes the delivery of investigative materials such as pressure sensitive film without causing artifact, difficult. Fortunately, a number of authors have studied the intact wrist, the scapholunate ligament injured wrist, the proximal row carpectomy and the scaphoid excision, four bone fusion. Despite some contrasting findings, there are some general concepts that we understand about wrist mechanics.

The Effect of Radioscapholunate Fusion With and Without Distal Scaphoid and Triquetrum Excision on Capitolunate Contact Pressures

PURPOSE

To determine the effects of motion-increasing modifications to radioscapholunate (RSL) arthrodesis on capitolunate contact pressure in cadaveric wrist specimens.

METHODS

Ten fresh-frozen cadaveric wrists were dissected of all superficial soft tissue, potted in polymethyl-methacrylate, and the carpus exposed via a ligament-sparing capsulotomy. An RSL arthrodesis was simulated using 2 2.4-mm distal radius plates with locking screws. The distal scaphoid pole and triquetrum were removed with an osteotome and rongeur, respectively. Contact area, pressure, and force were measured in the capitolunate joint during the application of a 35-N uniaxial load using pressure-sensitive film. Measurements were obtained before and after simulated RSL fusion, following distal scaphoidectomy and after triquetrectomy.

RESULTS

The combination of RSL fusion with distal scaphoid excision (DSE) increased contact forces in the capitolunate joint by 50% over controls. An RSL fusion, and RSL fusion with DSE and triquetrum excision (TE), exhibited intermediate levels of contact force between controls and RSL fusion with DSE. Capitolunate contact pressures were similar between all experimental groups. Contact area in the capitolunate joint increased by 43% after RSL fusion with DSE over intact specimen controls. Lastly, contact area in wrists with RSL fusion, and RSL fusion with DSE and TE, were elevated, but not significantly different from intact controls.

CONCLUSIONS

A DSE performed at the time of RSL fusion results in increased midcarpal joint contact force and area, with resultant contact pressures unchanged. Triquetrectomy, which has been previously shown to improve range of motion, did not increase contact forces in the capitolunate joint.

CLINICAL RELEVANCE

If a surgeon is contemplating performing an RSL arthrodesis with DSE, we recommend adding a triquetrectomy to improve motion because this does not add to the potentially deleterious effects of increased midcarpal contact force.

Four-Corner Arthrodesis: Description of Surgical Technique Using Headless Retrograde Crossed Screws

BACKGROUND

Four-corner fusion has been shown to be a reliable option of treatment of wrist arthritis, but there is no consensus about which implant and surgical procedure should be used in the arthrodesis. The present study aimed to describe a surgical technique using 2 crossed screws as implants, inserted in a retrograde manner, and to demonstrate preliminary results of the use of the technique.

METHODS

A retrospective study was conducted using medical records and imaging tests (radiographs and computed tomography) of all 15 patients who underwent a standardized 4-corner fusion technique, between December 2011 and July 2015, in the Department of Hand Surgery of Instituto Nacional de Traumatologia e Ortopedia (INTO), Rio de Janeiro, Brazil. We collected data on the following variables: fusion rate, time to fusion, and percentage of patients who had any complications or needed another surgical procedure on the same wrist.

RESULTS

All but one patient achieved fusion of arthrodesis. The average time to union was 5.54 months (SD = 3.84). Only the patient who developed nonunion of the 4-corner fusion required another surgery on the same wrist.

CONCLUSIONS

The procedure described in this study demonstrated a low complication rate and high fusion rate, and can therefore be considered a reliable surgical technique for 4-corner fusion.

Four-corner arthrodesis employing the native scaphoid as the principal donor graft for advanced collapse deformity of the wrist: technique and outcomes

The purpose of this study was to determine the functional, radiographic, and subjective outcome of the authors' technique of four-corner arthrodesis using the en bloc excised scaphoid as the principal donor bone graft coupled with Kirschner wire fixation. The study comprised 40 consecutive patients with progressive Stage II and III scapholunate advanced collapse or scaphoid nonunion advanced collapse deformities. Preoperative and postoperative range of motion, grip strength, carpal height, and Michigan Hand Outcomes Questionnaire responses were assessed with a mean follow-up of 4.4 years. At an average of 7 weeks, all patients demonstrated radiographic fusion. Moreover, postoperatively, improvement in the Michigan Hand Outcomes Questionnaire domains of overall function, activities of daily living, work performance, pain, and satisfaction were statistically significant. Complications were few and no patient required revision surgery. In this study, the authors' technique results in a reliable four-corner arthrodesis with a low expectation of complications or revision surgery.

LEVEL OF EVIDENCE

IV.

The Effect of Capitate Position on Coronal Plane Wrist Motion After Simulated 4-Corner Arthrodesis

PURPOSE

The objective of this study was to examine the effect of altering the capitolunate relationship on coronal-plane wrist motion after scaphoidectomy and simulated 4-corner arthrodesis. Two positions of different capitolunate alignments were compared: "anatomic" (unchanged from pre-fusion) and "lunate-covered" (capitate translated to cover the lunate). We hypothesized that wrist resting posture would be altered and radial-ulnar motion would diminish after 4-corner arthrodesis in the lunate-covered position when compared with normal wrists.

METHODS

Six human cadaveric limbs were disarticulated at the elbow and mounted on a custom jig. The resting position of the wrist was recorded with no load applied, followed by a load of 44 N applied to the flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis tendons to simulate radial deviation and to the flexor carpi ulnaris and extensor carpi ulnaris tendons to simulate ulnar deviation. Scaphoidectomy was performed and 2 methods of 4-corner arthrodesis with different capitolunate coronal alignments were studied in random order. Range of motion was compared using one-way analysis of variance and Bonferroni correction.

RESULTS

The "lunate covered" wrist demonstrated significantly greater radial resting posture than that of the preoperative wrist. Under a 44 N load, the lunate-covered position had significantly greater radial motion than the preoperative radial motion. Wrists fused in the "anatomic" position did not differ significantly from the preoperative wrists in posture or range of motion.

CONCLUSIONS

In this cadaveric model, complete covering of the capitate head by the lunate placed the wrist in increased radial deviation compared with the anatomic posture. Changes induced in the resting tension of the extrinsic wrist ligaments serve as a reasonable explanation for the increased radial posture and motion. In a clinical setting, these changes may affect postoperative wrist posture and function.

CLINICAL RELEVANCE

Maintaining anatomic lunate position leads to preservation of greater wrist motion and anatomic alignment in a patient undergoing 4-corner arthrodesis.

[Capitolunate arthrodesis: 12 patients followed-up an average of 10 years]

The aim of the study was to evaluate long-term results of capitolunate arthrodesis for the treatment of posttraumatic degenerative wrist disorders. A capitolunate arthrodesis was performed on 12 patients, three women and nine men, of 45 years on average (28-66). Ten patients were manual workers. Dominant side was involved in seven cases. Indications were nine scapholunate dissociations (SLAC) and three scaphoid non-unions (SNAC) with degenerative lesions. Fixation of the arthrodesis was performed with K-wires in seven, K-wires and staples in two, and only staples in three. Patients were reviewed at 118 months of average follow-up (72-168). One complete wrist arthrodesis was necessary one year after the capitolunate arthrodesis for an evolutive painful osteoarthritis. For the 11 remaining patients, pain on visual analogic scale (VAS) was 0.5. The flexion/extension arc was decreased of 25° and strength of 6kg compared to preoperative values. DASH score was equal to 33.7 points, Cooney score to 77.2 points and Mayo score to 82.8 points. Radiolunate and capitolunate angles were decreased of 4.9° and 6.2° respectively compared to preoperative values. Some complications occurred: evolutive osteoarthritis between triquetrum and lunate in two, non-union of the arthrodesis in one, and reflex sympathetic dystrophy in two. Nine patients were able to return to their previous professional activities. Capitolunate arthrodesis allowed restoring a pain free and functional wrist in eight out of the 11 patients reviewed. Results were maintained with follow-up. It is a satisfactory therapeutic alternative to four corners fusion for chronic instability of the wrist with osteoarthritis.

LEVEL OF EVIDENCE

IV.

Scaphoid excision and 4-bone arthrodesis versus proximal row carpectomy: a comparison of contact biomechanics

PURPOSE

We compare scaphoid excision and 4-bone arthrodesis (FBA) with proximal row carpectomy (PRC) in terms of contact pressure, area, and location.

METHODS

Six cadaveric forearms underwent simulated FBA with K-wires. We measured pressures in the radiocarpal joint with Fuji contact film after we applied a 200-N load via the wrist tendons with the wrist in neutral, flexion, and extension. We repeated the experiment after excising the lunate and triquetrum, to create a PRC in the same specimens.

RESULTS

Contact pressure in the PRC wrist was significantly greater, by 25%, compared with the FBA wrist for all wrist positions. The PRC wrist had a significantly smaller contact area, by 43%, compared with the FBA wrist. In the FBA wrist, lunate contact was more dorsal in flexion but more volar in extension. In the PRC wrist, capitate contact was more dorsal and radial in flexion, whereas the contact was more volar and ulnar in extension. Comparing contact location, FBA contact was significantly more ulnar than PRC contact in wrist flexion. We found no significant difference in contact translation (the distance between the contact locations in the positions of wrist flexion and extension) for the lunate in FBA or the capitate in PRC.

CONCLUSIONS

The FBA wrist has significantly lower contact pressure (P < .001), greater contact area (P < .001), and equal contact translation compared with the PRC wrist. These qualities may make FBA less susceptible to degeneration over time. By advancing our understanding of the biomechanics of both wrist procedures, we may better tailor them to the individual patient.

CLINICAL RELEVANCE

Current biomechanical evidence is lacking for common motion-preserving procedures for wrist arthritis. Comparing contact pressure, area, and location provides a biomechanical basis of our clinical understanding of these surgeries.

Analysis of wrist motion following vascularized bone graft to the proximal scaphoid

PURPOSE

To determine whether there is any motion loss associated with the 1,2 intracompartmental supraretinacular artery (ICSRA) bone graft to the dorsal scaphoid. The null hypothesis is that placement of a vascularized bone graft in the dorsal scaphoid does not lead to a significant change in range of motion.

METHODS

Seven fresh-frozen cadaveric upper extremities were examined. Simulated 1,2 ICSRA bone grafts were harvested and placed into a dorsal trough made in the proximal scaphoid. Wrist motion measurements were performed before and after 1,2 ICSRA bone graft implantation.

RESULTS

There were no significant changes in wrist motion following 1,2 ICSRA bone graft implantation.

CONCLUSIONS

Properly placed 1,2 ICSRA vascularized bone grafts for treatment of proximal scaphoid nonunions do not by themselves cause loss of wrist motion.

CLINICAL RELEVANCE

Loss of motion following the treatment of proximal scaphoid nonunions with properly placed 1,2 ICSRA vascularized bone grafts are due to factors other than the bone graft itself.

Scaphoid hemiresection and arthrodesis of the radiocarpal joint

Radiocarpal arthritis is frequently the result of trauma and/or degenerative disease. The leading causes are malunited or nonunited fractures of the radius or scaphoid, radiocarpal or intercarpal dislocations or dissociations, or a form of primary osteoarthritis or inflammatory arthritis. Management focuses on reducing pain, increasing function, and preserving some degree of motion when possible. Total wrist arthrodesis remains the ultimate salvage procedure. Several surgical procedures attempt to preserve some motion including proximal row carpectomy; lunotriquetrocapitohamate (4-corner) or luno-capito-hamate (3-corner) fusion with scaphoid excision; radiolunate or radioscapholunate; and lunocapitate arthrodesis, and total wrist replacement arthroplasty. These have been used with various success rates. The choice of the procedure depends on which articulation(s) are diseased and which are spared. Motion-sparing procedures require healthy articular cartilage at the site of preserved motion. This paper described scaphoid hemiresection and arthrodesis of the radiocarpal joint, the SHARC procedure.

Biomechanical effect of triquetral and scaphoid excision on simulated midcarpal arthrodesis in cadavers

PURPOSE

To examine the biomechanical effects of triquetral and scaphoid excision on wrist motion and radiolunate contact characteristics in a cadaveric model after simulated 4-corner arthrodesis with rigid internal fixation.

METHODS

Ten fresh-frozen cadaveric upper extremities were studied. For all surgical manipulations, the motion was measured and contact characteristics were assessed using ultralow prescale pressure-sensitive film.

RESULTS

Compared with the intact specimen, simple 4-corner arthrodesis with scaphoid retention led to a significant decrease in flexion (-23%), extension (-69%), radial deviation (-129%), and ulnar deviation (-25%), but no significant change in radiolunate contact characteristics. After 4-corner arthrodesis with scaphoid excision, there was a significant increase in radial deviation (+213%) without significant change in radiolunate contact characteristics, but average radial deviation was still less than in the intact specimen. After further excision of the triquetrum, radial deviation increased significantly (+238%), to a mean value 5% greater than that of the intact state, but at the cost of a significant increase in mean radiolunate contact pressure (+44% compared to the intact state).

CONCLUSIONS

When performing 4-corner arthrodesis, scaphoid and triquetrum excision may improve motion at the cost of increased mean radiolunate contact pressure.

Arthroscopic partial wrist fusion

The wide intraarticular exposure of the wrist joint under arthroscopic view provides an excellent ground for various forms of partial wrist fusion. Combining with percutaneous fixation technique, arthroscopic partial wrist fusion can potentially generate the best possible functional outcome by preserving the maximal motion pertained with each type of partial wrist fusion because the effect of extraarticular adhesion associated with open surgery can be minimized. From November 1997 to May 2008, the author had performed 12 cases of arthroscopic partial wrist fusion, including scaphotrapeziotrapezoid fusion in 3, scaphoidectomy and 4-corner fusion in 4, radioscapholunate fusion in 3, radiolunate fusion in 1, and lunotriquetral fusion in 1 case. Through the radiocarpal or midcarpal joint, the corresponding articular surfaces were denuded of cartilage using arthroscopic burr and curette. Carpal bones involved in the fusion process were then transfixed with K wires percutaneously after alignment corrected and confirmed under fluoroscopic control. Autogenous cancellous bone graft or bone substitute were inserted and impacted to the fusion site through cannula under direct arthroscopic view. Final fixation could be by multiple K wires or cannulated screw system. Early mobilization was encouraged. Surgical complications were minor, including pin tract infection, skin burn, and delay union in 1 case. Uneventful radiologic union was obtained in 9 cases, stable fibrous union in 2, and nonunion in 1. The average follow-up period was 70 months. Symptom was resolved or improved, and functional motion was gained in all cases. All surgical scars were almost invisible, and aesthetic outcome was excellent.

Scaphoid excision with four-corner fusion: a biomechanical study

PURPOSE

Partial wrist arthrodesis is a commonly performed procedure for the treatment of posttraumatic wrist arthritis because of its ability to provide pain relief without sacrificing complete wrist motion. The purpose of this study was to evaluate the redistribution of force after four-corner fusion and scaphoid excision, and to correlate the findings with the reported clinical outcomes.

METHODS

Fifteen cadaveric wrists were used to study the biomechanics of the four-corner fusion. Pressure-sensitive film (super-low-pressure-indicating film-Pressurex, Sensor Products Inc, Madison, NJ) was inserted into the radiocarpal joint. Using the MTS 858 Mini Bionix (MTS System, Eden Prairie, MN), 50-kg loads (220 N) were applied to the wrists before and after simulated four-corner fusion and scaphoid excision. Statistically, we compared the pressure in the normal (intact) wrists versus four-corner fusion and scaphoid excision. The pressure measurements across the scaphoid fossa, lunate fossa, and triangular fibrocartilage complex (TFCC) were compared.

RESULTS

There is a statistical significant difference between scaphoid, lunate, and TFCC mean total force when pre and post-fusion were compared (p = 0.0001). Our study revealed a statistical significant decrease in the mean scaphoid total force after scaphoid excision and four-corner fusion (p = 0.0001). We also found a subsequent increase in mean total force after scaphoid excision and four-corner fusion for the lunate fossa that did not reach statistical significance (p = 0.08), and no difference in load across the TFCC area (p = 0.995).

CONCLUSIONS

Our findings suggest that load is preferentially transferred to the radiolunate joint after scaphoid excision with four-corner fusion.

Pisotriquetral dysfunction following limited and total wrist arthrodesis

PURPOSE

We report a series of pisotriquetral arthritis cases following wrist and intercarpal arthrodesis, offer an anatomic and biomechanical rationale, and introduce intraoperative considerations to avoid this potential complication.

METHODS

Nine patients with pisotriquetral arthritis requiring pisiform excision following wrist and intercarpal arthrodesis were retrospectively evaluated at 2 institutions. Five paired cadaver wrists were tested for alterations in pressure and kinematics of the pisotriquetral joint following four-corner and total wrist fusions.

RESULTS

Nine patients were successfully treated with pisiform excision for pisotriquetral arthritis following wrist and intercarpal fusions. Biomechanical cadaver testing demonstrated profound alterations in pisotriquetral kinematics and pressure changes in measured degrees of wrist position following wrist and intercarpal fusions.

CONCLUSIONS

Patients undergoing four-corner and/or wrist arthrodesis should be assessed for pisotriquetral discomfort before surgery, including a physical examination and a 30 degrees supinated radiograph to look for degenerative changes. Attempts should be made intraoperatively to ensure that the proximal row is not fused in an extended position. After surgery, if discomfort develops and conservative treatment fails, then pisiform excision can successfully alleviate the pain.

Four-corner arthrodesis: influence of the position of the lunate on postoperative wrist motion: a cadaveric study

PURPOSE

Evaluate the influence of the position of the lunate on postoperative wrist motion in four-corner arthrodesis.

METHODS

Six upper cadaveric limbs were evaluated, comparing the total arc of motion in each wrist after simulating four-corner arthrodesis. The lunate was fixed in 3 different positions: neutral (0 degrees ), extended (30 degrees ), and flexed (20 degrees ). Statistical analyses (ANOVA and Bonferroni tests) were carried out to establish the significance of differences in articular motion in these 3 positions.

RESULTS

Significant statistical differences were observed in full wrist extension. No significant differences, however, were found in flexion-extension total arc of motion, radial deviation, or ulnar deviation.

CONCLUSIONS

According to our results in this cadaveric model, the position of the lunate affects postoperative wrist flexion and extension after four-corner arthrodesis. The flexed lunate position increases postoperative wrist extension and restrains wrist flexion. Inversely, the extended lunate position improves articular flexion and limits extension. Total arc of motion of the fused wrist does not vary in the 3 lunate positions.