Pancarpal dissociation, a very rare type of injury: A case report

RATIONALE

Pan-carpal dissociation is very rare injury and there is little information as to diagnosis, treatment, and prognosis of this injury.

PATIENT CONCERNS

A 35-year-man presented to our hospital with severe pain and swelling of the left wrist and forearm after slipping and falling while riding a motorcycle.

DIAGNOSIS

The wrist simple radiographs demonstrated unrecognizable severe fracture-dislocation of the carpal bones concomitant with fractures of the radioulnar shaft. Three-dimensional computed tomography revealed a capitate fracture-dislocation, as well as hamate dislocation, lunotriquetral (LT), and scapholunate (SL) dissociation. These findings suggested pan-carpal dissociation.

INTERVENTIONS

To prevent compartment syndrome, fasciotomy, carpal tunnel release, and open reduction and plate fixation for both bone fracture were performed first. Then, for pan-carpal dissociation, the capitate, carpometacarpal joint (CMCJ), and hamate were reduced and fixed first. Then, the SL, LT, and other intercarpal ligaments were repaired. Finally, additional trans-carpal pins to reinforce the ligament repair and 2.0 mm plate to buttress the third CMCJ were fixed. The patient was instructed to begin gentle range of motion exercises of the wrist with pins from four weeks after surgery and all pins were removed at six weeks postoperatively.

OUTCOMES

12 months after the operation, the patient exhibited almost full range of motion with mild pain with VAS (Visual analogue scale) 1-2 at rest and VAS 3-4 with effort. Quick DASH (the disabilities of the arm, shoulder and hand) score was 25 and modified Mayo score was 70. The radiographs demonstrated union of the radioulnar shaft, and the carpal bone alignment was successfully maintained.

LESSONS

Pan-carpal dissociation can be diagnosed in patients with capitate fracture-dislocation, hamate dislocation, LT, and SL dissociation. This pattern of injury is very rare and the authors recommend reduction and fixation of the distal carpal row, followed by the proximal row to facilitate an easy approach to the distal carpal row. Although it is very severe injury, rigid anatomical fixation and an early rehabilitation can lead to favorable functional outcomes.

Four-corner fusion versus proximal row carpectomy : a retrospective review with a minimal follow-up of 9 years

A retrospective survey on the long-term outcomes of both proximal row carpectomy (PRC) and scaphoidectomy with 4-corner arthrodesis (4CA) was conducted. Seventeen PRC and nine 4CA wrists were retrieved with a minimal follow-up of 9 years. Pain, satisfaction and disability were not significantly different. There was a better flexion and ulnar deviation in the PRC wrists. Conclusion : at long term, the outcome for PRC remains stable despite some series recently reported worsening of the results due to progressive degenerative arthritis. PRC seems to yield comparable clinical results compared to 4CA but a slightly better range of motion than 4CA.

[Proximal row carpectomy in patient with wrist osteoarthritis]

The arthrosis of the wrist is a degenerative, traumatic or idiopathic process, which cause problem for patient characterized by pain, loss of mobility, swelling and deformity of the affected wrist. A surgical alternative is proximal row carpectomy, which consists of resection of the lunate, scaphoid and triquetrum, forming a new joint between the radius and the distal row carpus. Material and methods: Observational, descriptive, case series. 15 patients were evaluated who underwent proximal row carpectomy during the period January 2007-August 2009, with clinical follow-up until august 2010 through mayo and DASH scores, measuring strength. Range of motion and pain. 80% of patients were between 35 and 64 years. The predominant sex was male in 67%. The result was satisfactory in 73%, according to the scale of Mayo. The DASH scale in the postoperative period also improves. Conclusions: The proximal carpectomy is a surgical alternative, it preserves some joint mobility, reduced pain and improved disability of the limb.

Distal Radius Allograft Reconstruction Utilizing a Step-Cut Technique After En Bloc Tumor Resection

Background: En bloc resection of the distal radius is a common treatment for advanced and recurrent giant cell tumors and less commonly for sarcoma. Various reconstructive options exist, including ulnar transposition, osteoarticular autograft and allograft, and allograft arthrodesis. We present a technique of reconstruction using a distal radius bulk allograft with a step-cut to allow for precise restoration of proper length and to promote bony union. Methods: Preoperative templating is performed with affected and contralateral radiographs to assess the size of the expected bony defect, location of the step-cut, and the optimal size of the distal radius allograft required. A standard dorsal approach to the distal radius is utilized, and the tumor is resected. A proximal row carpectomy is performed, and the plate/allograft construct is applied to the remaining host bone. Iliac crest bone graft is harvested and introduced at the graft-bone interface and radiocarpal arthrodesis sites. Results: We have previously reported outstanding union rates with the step-cut technique compared with a standard transverse cut. Conclusions: The technique described provides reproducible union and stabilization of the wrist and forearm with adequate function following en bloc resection of the distal radius for tumor.

Fibroma of tendon sheath embedded in carpal bones mimicking carpal enchondroma: A case report

RATIONALE

Fibroma of tendon sheath is a rare entity that is typically attached to the tendon sheath.

PATIENT CONCERNS

A 43-year-old man presented with a painful mass in his right wrist, which was initially misdiagnosed as an enchondroma.

DIAGNOSIS

Fibroma embedded into carpal bones, which exhibited lytic radiographic features similar to those of enchondroma. Excisional biopsy demonstrated spindle-shaped cells and collagen-like stroma.

INTERVENTIONS

The patient underwent lesion resection surgery.

OUTCOMES

The patient recovered well and showed no signs of recurrence at 6-month follow-up.

LESSONS

This case provides valuable insights for hand surgeons. While radiograph is helpful in multiple diseases, histological examination is indispensable for establishment of final diagnosis.

Carpal tunnel release with versus without flexor retinaculum reconstruction for carpal tunnel syndrome at short- and long-term follow up-A meta-analysis of randomized controlled trials

Background

Carpal tunnel syndrome is a common neuropathy disorder for which surgical treatment consists of release and reconstruction of the flexor retinaculum. Reports of postoperative clinical outcomes after carpal tunnel release with or without flexor retinaculum reconstruction in several studies are controversial. This meta-analysis aimed to compare the efficacy and safety of carpal tunnel release with or without flexor retinaculum reconstruction.

Methods

The PubMed, EMBASE, Web of Science, Ovid, Cochrane Library and Clinical Tri Org databases were searched for randomized controlled trials that compared carpal release with and without transverse carpal ligament reconstruction for carpal tunnel syndrome. Outcomes included postoperative Boston Carpal Tunnel Questionnaire Symptom Severity Scale (SSS), Functional Status Scale (FSS), grip strength and complications. The follow-up time was categorized into short-term (0-3mon) and long-term(>3mon).

Results

A total of 7 studies with 613 patients met the inclusion criteria and were analyzed in detail. Statistical analysis showed no significant difference between two groups on postoperative long-term grip strength (MD 5.85, 95% CI -1.05 to 12.76) long-term SSS (MD -0.31, 95% CI -0.75 to 0.13) and occurrence of complications (RR 1.14, 95% CI 0.84 to 1.54), whereas statistically significant difference was found between groups regarding short-term grip strength (MD 1.51, 95% CI 0.86 to 2.17) and long-term FSS (MD -0.34, 95% CI -0.47 to -0.21).

Conclusion

Carpal tunnel release with flexor retinaculum reconstruction for carpal tunnel syndrome may result in improved long-term functional status while there’s no advantage regarding grip strength, symptom severity and safety over individual carpal tunnel release in short- and long-term outcomes.

Preiser disease after repeated local glucocorticoid injections: A case report

RATIONALE

Preiser disease or avascular necrosis (AVN) of the scaphoid causes intolerable wrist pain and malalignment of the carpal bones. In previously reported cases, patients have had a history of steroid use for systemic illness such as autoimmune hemolytic anemia, systemic lupus erythematosus, or renal transplantation, or have had other risk factors, such as smoking, alcoholism, or infection. In particular, systemic glucocorticoid therapy has been most commonly associated with the disease. Although there are reports of AVN of the scaphoid induced by systemic glucocorticoids, no prior report has associated AVN of the carpal bones with repeated local injections of glucocorticoids.

PATIENT CONCERNS

We present a case in which it was strongly suspected that AVN of the scaphoid was induced by repeated local glucocorticoid injections. The patient had no history of excessive alcohol use, smoking, or trauma, except for local repeated steroid injections.

DIAGNOSES

Initially, she had diagnosed with de Quervain's disease and was treated by repeated local glucocorticoid injections followed by surgery for de Quervain's disease. Five years after surgery for de Quervain's disease, the patient presented at our hospital with sudden onset of intolerable pain in her right wrist without a history of trauma. In spite of nonsurgical treatment with rest, immobilization, analgesia, and surgery, her wrist pain was not improved. After further repeated local steroid injections in her wrist, radiographs, and magnetic resonance imaging of her wrist showed the AVN of the scaphoid.

INTERVENTIONS

Surgery was performed and the fragmented proximal scaphoid and the entire lunate were resected.

OUTCOMES

The diagnosis was confirmed according to the histopathological examination of the proximal scaphoid bone, which showed the characteristic of AVN of the scaphoid. At follow-up evaluation, radiographs of the right wrist showed no progression of osteoarthritis. The patient had no tenderness or residual pain at the wrist and had no desire to pursue additional surgery.

LESSONS

We have presented a case with AVN of the scaphoid, which was strongly suspected to be associated with the repeated local steroid injections. Further studies are required to more fully elucidate the association between AVN of the scaphoid and repeated local steroid injections.

Autosomal dominant stapes fixation, syndactyly, and symphalangism in a family with NOG mutation: Long term follow-up on surgical treatment

OBJECTIVE

Evaluation of clinical findings and audiological outcome after surgery in a Danish family with autosomal dominant facio-audio-symphalangism syndrome with stapes fixation, syndactyly and symphalangism.

METHODS

Retrospective report on eight affected family members in a Danish family. Clinical investigation included X-ray, audiology and in one case video-recorded surgery. Main outcome measure was audiologic results after stapedectomy. Sanger DNA sequencing of NOG was performed on peripheral blood.

RESULTS

Audiologic analysis showed that seven of eight affected family members had bilateral conductive hearing loss. Three patients were treated with stapedectomy, on one or both ears, due to fixation of stapes. All the affected members had syndactyly and symphalangism. A not previously reported mutation in the NOG gene (c.688_699del, p.Cys230_Cys232delins11) was found to segregate with the stapes fixation, syndactyly, and symphalangism. p.Cys230_Cysdelins11 was classified as likely pathogenic according to guidelines from the American College of Medical Genetics and Genomics.

CONCLUSION

The clinical presentation of the reported mutation corresponds with previous case reports of families with NOG mutation. In this family, surgery with stapedectomy had lasting effect without renewed fixation of the stapes in a follow up period of 18 months-38 years.

Perihamate-Peripisiform-Transtriquetrum Axial Ulnar Fracture Dislocation of the Hand With an Associated Perilunate Injury

Axial fracture-dislocations are rare, high-energy injuries. Although cases of axial fracture-dislocations are reported in the literature, there are few reports of a patient who suffered a combined perilunate injury with an ulnar axial dislocation of the hand. This case report describes the anatomical injury and operative treatment of a patient who suffered this injury and discusses the importance of associated soft tissue management.

[Proximal Row Carpectomy - Five-Year Results]

PURPOSE OF THE STUDY This study aims to evaluate the results of patients treated by proximal row carpectomy at a follow-up of at least 5 years after the surgery. MATERIAL AND METHODS A total of 25 patients were treated by proximal row carpectomy for degenerative changes of the wrist as a consequence of the previous trauma or avascular necrosis of the lunate bone, of whom 21 patients underwent a follow-up examination at least 5 years postoperatively. Proximal row carpectomy was indicated in 15 patients for SLAC wrist, in 4 patients for avascular necrosis of the lunate bone, in 1 patient for SNAC wrist, and in 1 patient for inveterate dislocation of the wrist. The follow-up clinical and radiological examinations were performed at least 5 years after the surgery. The range of wrist motion, grip strength, presence of pain at rest or pain under loads, total clinical score according to the Green and O'Brien scoring system, patient satisfaction with the outcome of surgery were assessed. By fluoroscopy the range of wrist motion, degenerative changes of the radiocapitate joint, and translation of the capitate bone with respect to the distal radius were evaluated. RESULTS Postoperative improvements in the range of motion and grip strength were confirmed. Also, the pain relief at rest and under loads was achieved. Five years after the surgery, most of the patients (85.6%) reported an overall improvement. The total clinical score according to the Green and O'Brien scoring system improved from 35.8 preoperatively to 63.1 postoperatively. DISCUSSION The advantage of this procedure is a low percentage of complications, relative technical simplicity, maintenance of functional motion of the wrist, satisfactory grip strength, and pain relief. There are no complications related to the implant, no risk of a non-union. CONCLUSIONS As shown by our results obtained 5 years after the surgery as well as the published data, in the indicated cases the proximal row carpectomy is an appropriate surgical technique to treat the degenerative changes of the wrist. In most of the patients, favourable functional results and pain relief can be expected. Key words:proximal row carpectomy, SLAC wrist, SNAC wrist, avascular necrosis of the lunate bone, dislocation of the wrist.

The Role of Wrist Arthroscopy in Kienbock Disease

Kienbock disease (KD) is a disease of uncertain etiology, leading to chondral and osseous change in the lunate and wrist. Traditionally, Lichtman's classification of KD, based on radiographic appearances, has been used to direct treatment. Diagnostic wrist arthroscopy allows direct assessment of the lunate and surrounding articulations. Wrist arthroscopy can also serve as a therapeutic tool for performing debridement, resection, or arthrodesis procedures. The new Lichtman-Bain algorithm takes into consideration the status of the lunate, the effect on the wrist, and surgical and patient factors to guide management.

Proximal Row Carpectomy and 4-Corner Arthrodesis in Patients Younger Than Age 45 Years

PURPOSE

To examine the long-term outcome of patients aged less than 45 years who underwent either proximal row carpectomy (PRC) or 4-corner arthrodesis (4CA) for wrist arthritis.

METHODS

We reviewed a retrospective cohort of 89 patients aged less than 45 years who underwent either 4CA (n = 51) or PRC (n = 38) for wrist arthritis. Mean follow-up was 11 years in the 4CA group and 18 years in the PRC group.

RESULTS

Overall, there were no differences between groups in the need for revision surgery. Complications included 6 nonunions in the 4CA group (12%), 1 infection in each group, and 11 patients who experienced radiocarpal impingement (8 4CA and 3 PRC). There was no difference in the number of patients reporting moderate or severe pain between the PRC and 4CA groups. Mean flexion-extension arc was 54° after 4CA, compared with 73° after PRC. Patients who underwent 4CA had slightly improved grip strength (65% of the opposite side) compared with those who had PRC (54%). Mean postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire scores were 32 versus 19 (PRC vs 4CA) and patient-rated wrist evaluation scores were 27 versus 28 (PRC vs 4CA). Comparing radiographic arthritis, the 10-year outcome, free of moderate/severe arthritis for the PRC and 4CA groups, was 70% and 71%, respectively.

CONCLUSIONS

Both PRC and 4CA represent a good surgical option for young patients with wrist arthritis, with similar complication rates, postoperative pain levels, wrist function, and long-term outcomes free of arthrodesis. Proximal row carpectomy has improved motion and fewer complications.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Total wrist arthrodesis for septic wrist arthritis and loss of the bony carpus following percutaneous pinning of the fifth carpometacarpal joint: a case report

We report on a patient who developed septic wrist arthritis with destruction of the entire carpus due to osteomyelitis following percutaneous pinning of a fifth metacarpal base fracture. Arthrodesis was performed using a 6 cm vascularized iliac bone graft. This case report may sharpen the surgeon's awareness of risks in orthopedic surgeries, even though the procedure seems to be rather simple and the patient is young and seems to be healthy.

Trans-Scaphoid Transcapitate Perilunate Fracture-Dislocation

Trans-scaphoid transcapitate (TSTC) perilunate fracture-dislocation (PLFD) is a rare type of perilunate injury. Because of the rarity and complexity of this entity, initial diagnosis may be delayed and the extent of osseous and ligamentous lesions underestimated. Early surgical treatment by open reduction and fracture stabilization is recommended to avoid complications such as avascular necrosis, nonunion, posttraumatic arthritis, and functional impairment. In this article, we report the case of a 32-year-old man who sustained a TSTC-PLFD. We describe the radiographic and intraoperative findings, review the current surgical principles for reduction and stabilization of this injury, and assess the clinical and radiologic outcomes.

Proximal row carpectomy on manual workers: 17 patients followed for an average of 6 years

Proximal row carpectomy (PRC) is indicated for the treatment of SNAC or SLAC wrist with preservation of the midcarpal joint. Our hypothesis was that PRC is not appropriate for treating advanced wrist osteoarthritis in patients who carry out heavy manual work. Twenty-three PRCs were performed on 21 patients, 5 women and 16 men with an average age of 54 years (33-77). All patients performed manual work; 11 of them performed heavy manual work. Etiologies were: SLAC wrist in 14 cases (2 stage III, 11 stage II, and 1 stage I) and SNAC wrist in 9 cases (6 stage IIIB and 3 stage IIB). At an average 75 months' follow-up (24-153), five patients were lost to follow-up. Radiocarpal arthrodesis was performed in one patient 10 years after the PRC. In the 17 remaining patients (18 wrists), pain (VAS) averaged 2.2, with residual pain of 5. Flexion-extension range was similar to preoperative levels (67% of contralateral wrist). Wrist strength was decreased by 34% compared to preoperative. The QuickDASH score averaged 26 points and the PRWE 20 points. Radiocapitate distance decreased by 0.3mm on average with joint line narrowing in 6 patients. The carpal translation index was 0.33mm, which was unchanged relative to preoperative values. Three patients had work-related limitations that required retraining and one patient had to be reassigned. PRC preserved the preoperative range of motion and reduced pain levels. However, significant loss of strength was observed, resulting in 23% of manual workers needing retraining or reassignment.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Sagittal Wrist Motion of Carpal Bones Following Intraarticular Fractures of the Distal Radius

Forty patients (mean age, 37 years) with intraarticular C2 and C3 Colles fractures were treated by open reduction, internal fixation and bone grafting. At a mean follow-up of 8 years radiocarpal and midcarpal motion was evaluated, the depth of the articular surface of the distal radius in the sagittal plane was measured and the presence of arthritis was noted. The fractures healed with a mean palmar tilt of 6°, a mean ulnar tilt of 18° and ulna variance within 1 mm of the contralateral side. The depth of the articular surface of the distal radius was 1.3 mm greater than the uninvolved side. Measurement of carpal bone angles relative to the radius in maximum flexion and extension revealed lunate extension of 23°, lunate flexion of 15°, capitate extension of 62°, capitate flexion of 40°. There was a significant correlation between articular surface depth and radiocarpal motion.

Carpal Canal Pressures after Volar Plating of Distal Radius Fractures

Elevated pressures within the carpal canal are known to occur after distal radius fractures. Controversy exists regarding prophylactic carpal tunnel release after open reduction with internal fixation of distal radius fractures. The purpose of this study was to determine the tissue pressures within the carpal canal after volar plating of distal radius fractures. This study was a prospective, observational, IRB approved research study. Ten consecutive patients undergoing volar plating of distal radius fractures were enrolled. After the distal radius fractures were reduced and fixed with volar plates, slit catheters were inserted into the carpal canals for continuous postoperative pressure monitoring for 24 hours. The maximum recorded pressure was 65 mmHg, which occurred in the only patient with fracture blisters. Peak pressures remained at 40 mmHg or less (range 16–40, mean 29) in all patients without fracture blisters. At the conclusion of data collection, all pressures were at 31 mmHg or less. No patient complained of median nerve dysfunction during the study period. Routine prophylactic carpal tunnel release is not recommended after volar plating of distal radius fractures based on these pressure recordings.

A Comparison of Two Indices for Ulnar Translation and Carpal Height in the Rheumatoid Wrist

The indices for ulnar translation described by Chamay et al. (1983 , Annales de Chirurgie de la Main, Vol. 2, pp. 5–17), and Bouman et al. (1994 , Journal of Hand Surgery Vol. 19B, pp. 325–329), and for carpal height described by Youm et al. (1978 , Journal of Bone and Joint Surgery, Vol. 40A, pp. 423–431) and Bouman et al. (1994) were compared in pre- and postoperative wrist X-rays of 91 patients with rheumatoid arthritis undergoing radiolunate arthrodesis. Both indices described by Bouman had a higher applicability and sensitivity than the Chamay and Youm indices and are recommended for use with the rheumatoid wrist. However false-negative values may result when the Bouman index for ulnar translation is used to follow up radiolunate arthrodesis.

Inter-Carpal Soft Tissue Entrapment. A Possible Explanation for Chronic Dorsal Wrist Pain

This retrospective study evaluates the surgical treatment of a group of patients with unknown chronic dorsal wrist pain. The cause of their symptoms was interpreted as a painful entrapment of fibrous tissue in the radio-carpal and inter-carpal joints during specific movements. Between 1997 and 2001, 30 patients were treated by surgical excision of this tissue and 26 patients were traced for follow-up. Twenty-three patients were symptom free, or experienced major benefit from surgery. Wrist function measurements using the VAS scale showed improvement in 24 patients. Microscopic examination of the removed specimen shows fibrous tissue with non-specific changes. Inter-carpal soft tissue entrapment can explain the typical clinical findings in some patients with unknown chronic dorsal wrist pain. After careful selection, surgical excision of all entrapped tissue in the radio-carpal and mid-carpal joint may give relief of pain and improvement of wrist function.

Scaphotrapeziotrapezoid (STT)-Arthrodesis in Kienböck’s Disease

This study reviews the results of 59 of 84 patients with severe Kienböck’s disease who were treated with STT fusion. The average follow-up period was 4 (ranges: 2–8) years.

The average arc of wrist extension and flexion was 67° (60% of the contralateral side, 81% of pre-operative range) and that of ulnar and radial deviation was 31° (52% of the contralateral side, 56% of pre-operative range). Pre-operative pain values (VAS) were 56 (non-stress) and 87 (stress) and were significantly higher than the postoperative values of 12 (non-stress) and 41 (stress). Grip strength improved from 45 kPa pre-operatively to 52 kPa postoperatively. The mean modified Mayo wrist score was 63 points. The patients reported low disability in the DASH scores, with an average of 28 points.

Our data show that STT fusion is a reliable and effective treatment for pain relief and offers a good functional result in advanced stages of Kienböck’s disease. However the long-term effect of this procedure on radioscaphoid and other intercarpal joints is yet to be determined.

[Fractures of carpal bones]

Fractures of the carpal bones are uncommon. On standard radiographs fractures are often not recognized and a computed tomography (CT) scan is the diagnostic method of choice. The aim of treatment is to restore pain-free and full functioning of the hand. A distinction is made between stable and unstable carpal fractures. Stable non-displaced fractures can be treated conservatively. Unstable and displaced fractures have an increased risk of arthritis and non-union and should be stabilized by screws or k‑wires. If treated adequately, fractures of the carpal bones have a good prognosis. Unstable and dislocated fractures have an increased risk for non-union. The subsequent development of carpal collapse with arthrosis is a severe consequence of non-union, which has a heterogeneous prognosis.

Perilunate Injuries

Perilunate injuries often result from high-energy trauma to the carpus. Despite the severity of these injuries, they are often missed initially because of their subtle radiographic and physical examination findings. Early anatomic reduction of any carpal malalignment is paramount to a successful outcome. Even with optimal treatment, complications, such as generalized wrist stiffness, diminished grip strength, and posttraumatic arthritis, commonly develop; however, recent studies suggest these issues are often well tolerated. In this article, the basic presentation and treatment of perilunate injuries are discussed.

Clinical outcomes of proximal row carpectomy versus four-corner arthrodesis for post-traumatic wrist arthropathy: a systematic review

We conducted a systematic review of studies reporting clinical outcomes after proximal row carpectomy or to four-corner arthrodesis for scaphoid non-union advanced collapse or scapholunate advanced collapse arthritis. Seven studies (Levels I-III; 240 patients, 242 wrists) were evaluated. Significantly different post-operative values were as follows for four-corner arthrodesis versus proximal row carpectomy groups: wrist extension, 39 (SD 11º) versus 43 (SD 11º); wrist flexion, 32 (SD 10º) versus 36 (SD 11º); flexion-extension arc, 62 (SD 14º) versus 75 (SD 10º); radial deviation, 14 (SD 5º) versus 10 (SD 5º); hand grip strength as a percentage of contralateral side, 74% (SD 13) versus 67% (SD 16); overall complication rate, 29% versus 14%. The most common post-operative complications were non-union (grouped incidence, 7%) after four-corner arthrodesis and synovitis and clinically significant oedema (3.1%) after proximal row carpectomy. Radial deviation and post-operative hand grip strength (as a percentage of the contralateral side) were significantly better after four-corner arthrodesis. Four-corner arthrodesis gave significantly greater post-operative radial deviation and grip strength as a percentage of the opposite side. Wrist flexion, extension, and the flexion-extension arc were better after proximal row carpectomy, which also had a lower overall complication rate.

Wrist salvage procedures alter moment arms of the primary wrist muscles

BACKGROUND

Proximal row carpectomy and scaphoid-excision four-corner fusion are salvage procedures that relieve pain by removing arthritic joint surfaces. While numerous studies have examined how these procedures affect joint motion, few have examined how they influence muscle mechanical actions. This study examines whether muscle moment arms change after these procedures.

METHODS

Moment arms of primary wrist muscles were measured in 8 cadaveric specimens using the tendon excursion method. In each specimen, moment arms were measured for two degrees of freedom (flexion-extension and radial-ulnar deviation) and three conditions (nonimpaired, scaphoid-excision four-corner fusion, and proximal row carpectomy). For each muscle and degree of freedom, moment arm versus joint angle curves for the three conditions were statistically compared.

FINDINGS

Wrist salvage procedures significantly alter moment arms of the primary wrist muscles. Proximal row carpectomy primarily alters flexion-extension moment arms, while scaphoid-excision four-corner fusion primarily alters radial-ulnar deviation moment arms. Both procedures also alter the balance between agonist and antagonist wrist muscles. Following proximal row carpectomy, wrist extensors have smaller moment arms in extended postures. Following scaphoid-excision four-corner fusion, radial deviators have larger moment arms throughout radial-ulnar deviation.

INTERPRETATION

Different moment arms indicate that different forces are required to complete the same tasks in nonimpaired and surgically altered wrists. The altered muscle moment arms likely contribute to post-operative impairments. Understanding how salvage procedures alter muscle mechanical actions is a critical first step toward identifying the cause of post-operative impairments and is necessary to develop effective interventions to augment deficient muscles and improve overall function.