Aims. The ulna is an extremely rare location for primary bone tumours of the elbow in paediatrics. Although several reconstruction options are available, the optimal reconstruction method is still unknown due to the rarity of proximal ulna tumours. In this study, we report the outcomes of osteoarticular ulna allograft for the reconstruction of proximal ulna tumours. Methods. Medical profiles of 13 patients, who between March 2004 and November 2021 underwent osteoarticular ulna allograft reconstruction after the resection of the proximal ulna tumour, were retrospectively reviewed. The outcomes were measured clinically by the assessment of elbow range of motion (ROM), stability, and function, and radiologically by the assessment of allograft-host junction union, recurrence, and joint degeneration. The elbow function was assessed objectively by the Musculoskeletal Tumor Society (MSTS) score and subjectively by the Toronto Extremity Salvage Score (TESS) and Mayo Elbow Performance Score (MEPS) questionnaire. Results. The mean follow-up of patients was 60.3 months (SD 28.5). The mean elbow flexion-extension ROM was 95.8° (SD 21). The mean MSTS of the patients was 84.4 (SD 8.2), the mean TESS was 83.8 (SD 6.7), and the mean MEPS was 79.2 (SD 11.5). All the patients had radiological union at the osteotomy site. Symptomatic osteoarthritic change was observed in three patients (23%), one of whom ended up with elbow joint fusion. Two patients (15.4%) had recurrence during the follow-up period. Surgical complications included two allograft fractures, two plate fractures, three medial instabilities, and two infections. Conclusion. Osteoarticular ulna allograft reconstruction provides acceptable functional outcomes. Despite a high rate of complications, it is still a valuable reconstruction method, particularly in skeletally immature patients who need their distal humerus physis for the rest of hand growth. Cite this article: Bone Jt Open 2024;5(9):749–757

Aims. The primary aim of this study was to describe long-term patient-reported outcomes after ulna shortening osteotomy for ulna impaction syndrome. Methods. Overall, 89 patients treated between July 2011 and November 2017 who had previously taken part in a routine outcome evaluation up to 12 months postoperatively were sent an additional questionnaire in February 2021. The primary outcome was the Patient-Rated Wrist and Hand Evaluation (PRWHE) total score. Secondary outcomes included patient satisfaction with treatment results, complications, and subsequent treatment for ulnar-sided wrist pain. Linear mixed models were used to compare preoperative, 12 months, and late follow-up (ranging from four to nine years) PRWHE scores. Results. Long-term outcomes were available in 66 patients (74%) after a mean follow-up of six years (SD 1). The mean PRWHE total score improved from 63 before surgery to 19 at late follow-up (difference in means (Δ) 44; 95% confidence interval (CI) 39 to 50; p = <0.001). Between 12 months and late follow-up, the PRWHE total score also improved (Δ 12; 95% CI 6 to 18; p = < 0.001). At late follow-up, 14/66 of patients (21%) reported a PRWHE total score of zero, whereas this was 3/51 patients (6%) at 12 months (p = 0.039). In all, 58/66 patients (88%) would undergo the same treatment again under similar circumstances. Subsequent treatment (total n = 66; surgical n = 57) for complications or recurrent symptoms were performed in 50/66 patients (76%). The most prevalent type of reoperation was hardware removal in 42/66 (64%), and nonunion occurred in 8/66 (12%). Conclusion. Ulna shortening osteotomy improves patient-reported pain and function that seems to sustain at late follow-up. While satisfaction levels are generally high, reoperations such as hardware removal are common. Cite this article: Bone Jt Open 2022;3(5):375–382

Aims. The aim of this study was to assess the ability of morphological spinal parameters to predict the outcome of bracing in patients with adolescent idiopathic scoliosis (AIS) and to establish a novel supine correction index (SCI) for guiding bracing treatment. Methods. Patients with AIS to be treated by bracing were prospectively recruited between December 2016 and 2018, and were followed until brace removal. In all, 207 patients with a mean age at recruitment of 12.8 years (SD 1.2) were enrolled. Cobb angles, supine flexibility, and the rate of in-brace correction were measured and used to predict curve progression at the end of follow-up. The SCI was defined as the ratio between correction rate and flexibility. Receiver operating characteristic (ROC) curve analysis was carried out to assess the optimal thresholds for flexibility, correction rate, and SCI in predicting a higher risk of progression, defined by a change in Cobb angle of ≥ 5° or the need for surgery. Results. The baseline Cobb angles were similar (p = 0.374) in patients whose curves progressed (32.7° (SD 10.7)) and in those whose curves remained stable (31.4° (SD 6.1)). High supine flexibility (odds ratio (OR) 0.947 (95% CI 0.910 to 0.984); p = 0.006) and correction rate (OR 0.926 (95% CI 0.890 to 0.964); p < 0.001) predicted a lower incidence of progression after adjusting for Cobb angle, Risser sign, curve type, menarche status, distal radius and ulna grading, and brace compliance. ROC curve analysis identified a cut-off of 18.1% for flexibility (sensitivity 0.682, specificity 0.704) and a cut-off of 28.8% for correction rate (sensitivity 0.773, specificity 0.691) in predicting a lower risk of curve progression. A SCI of greater than 1.21 predicted a lower risk of progression (OR 0.4 (95% CI 0.251 to 0.955); sensitivity 0.583, specificity 0.591; p = 0.036). Conclusion. A higher supine flexibility (18.1%) and correction rate (28.8%), and a SCI of greater than 1.21 predicted a lower risk of progression. These novel parameters can be used as a guide to optimize the outcome of bracing. Cite this article: Bone Joint J 2022;104-B(4):495–503

Osteofibrous dysplasia is a rare condition usually affecting the tibiae and fibulae of males in the first two decades of life. Involvement at the ulna has also been reported in some cases. We describe an extensive, rapidly progressive lesion of the ulna in a three-year-old girl. The progression of the disease accelerated after a local marginal removal, and required extensive resection of the ulna with reconstruction using a fibular autograft. The particular features of this case are the change in the aggressive nature of the condition, which has not been previously reported. We believe that this is only the second recorded case of histologically proven involvement of the ulna

Two cases of congenital pseudarthrosis of the ulna due to neurofibromatosis are reported. Similar radiographic changes in the ulna were found, with distortion of the capitulum and part of the trochlea and bowing of the radius. In one patient the head of the radius was dislocated and in the other it dislocated readily during pronation. A possible mechanism to explain the findings was suggested. On the basis of these and a review of the literature it is recommended that the main aim of treatment should be maintenance of the normal relative lengths of the radius and ulna by early excision of the pseudarthrosis to remove the restraining effect of the abnormal ulna. This will allow normal development of the lower end of the humerus and radius and prevent dislocation of the radial head

We have assessed the influence of isolated and combined rotational malunion of the radius and ulna on the rotation of the forearm. Osteotomies were made in both the radius and the ulna at the mid-diaphyseal level of five cadaver forearms and stabilised with intramedullary metal implants. Malunion about the axis of the respective forearm bone was produced at intervals of 10°. The ranges of pronation and supination were recorded by a potentiometer under computer control. We examined rotational malunions of 10° to 80° of either the radius or ulna alone and combined rotational malunions of 20° to 60° of both the radius and ulna. Malunion of the ulna in supination had little effect on rotation of the forearm. Malunion of either the radius or of the ulna in pronation gave a moderate reduction of rotation of the forearm. By contrast, malunion of the radius in supination markedly reduced rotation of the forearm, especially with malunion greater than 60°. Combined rotational malunion produced contrasting results. A combination of rotational malunion of the radius and ulna in the same direction had an effect similar to that of an isolated malunion of the radius. A combination in the opposite direction gave the largest limitation of the range of movement. Clinically, rotational malunion may be isolated or part of a complex angular/rotational deformity and rotational malunion may lead to marked impairment of rotation of the forearm. A reproducible method for assessing rotational malunion is therefore needed

Purpose: We report three cases of extensive resection of the ulna without reconstruction. Material and methods: For the first two patients, resection was performed for ulnar tumour, on low-grade osteosarcoma and one adamantinoma. In the third patient with a voluminous giant-cell tumour, the distal part of the ulna was resected and used as a graft for arthrodesis after resection of the distal third of the homolateral radius. Resection involved the distal half, three-quarters, and one-third of the ulna in these three patients. Results: At follow-up of 4, 23 and 1 year respectively, wrist motion is normal in the two patients and elbow motion is normal in two out of three. None of the patients experienced wrist pain or ulnar stump pain. Grip force decreased in the two patients who underwent isolated ulnar resection. Discussion: Our observations corroborate reports in the literature leading to the conclusion that reconstruction of the ulna is not justified when one-quarter of the bone can be preserved. The ulna offers an exceptional graft material for reconstruction of the homolateral radius

Purpose of the study: The purpose of using distal metaphyso-epiphyseal osteotomy to shorten the ulna is to reduce healing time compared with diaphyseal shortening and to adapt the osteotomy to the distal radioulnar anatomy and associated conditions by using a variably oblique cut. Material and methods: Oblique metaphyso-eiphyseal osteotomy of the distal ulna was performed in sixteen patients since 2000. Fourteen presented ulnocarpal pain. Among these, eight had associated distal radioulnar pain. Two patients had pain essentially limited to the distal radioulnar area. Radiographically, there was ulnocarpal impingement in fourteen wrists, and signs of early-stage distal radioulnar osteoarthritis in five. Local regional anesthesia was used in thirteen patients who underwent surgery in an outpatient clinic. The dorsoulnar approach was used. The direction of the osteotomy cut depended on the individual condition, and distal radioulnar anatomy and stability. Two headless canulated screws were used for fixation. The elbow and wrist were immobilized for three weeks followed by self-education of pronosupination beginning with a removable orthesis to stabilize the wrist. Results: Outcome was assessed at maximum follow-up of four years. Preoperative pain had totally resolved in fourteen wrists with residual pain at forced pronosupination in two. Wrist motion was not modified in the frontal and sagittal planes. Complete pronosupination range of motion was achieved in thirteen patients, two patients had supination limited to 20° and one had pronation and supination limited to 30°. Force was 90% compared to the opposite side. Bone healing was achieved in all patients, in 3–4 weeks for fourteen wrists and after two months of elbow and wrist immobilization in two. Discussion: Oblique metaphyso-epiphyseal osteotomy of the distal ulna reduced the healing time compared with diaphyseal shortening osteotomies. This technique enables adaptation of the direction and orientation of the ulnar cut to the individual distal radioulnar anatomy. Favorable clinical outcome in patients with early-stage distal radioulnar osteoarthritis has led us to progressively abandon certain indications for distal resection of the ulna and the Sauvé-Kapankji operation

Non-union of the radius and/or ulna is comparatively common in the treatment of forearm fractures. Bone graft from the iliac crest secured by rigid plate fixation under compression is indicated in non-unions with a bone defect longer than 2 cm. The aim of the study is to compare the results with the current literature. Thirteen patients (female: 1; males: 12), mean age 44 years (23–75 years), were treated in our department between 1993 and 2003. In 10 patients the original injury involved both radius and ulna; in the remaining three only the ulna was affected. All the fractures had been internally fixed, except for a radius fracture. Non-unions involved the ulna in eight cases, the radius in one case and both radius and ulna in four cases. A cortico-cancellous graft was used to fill a defect of the ulna in 11 cases and of the radius in two cases. In the non-unions of both bones only one bone was operated (one radius and three ulna); a different treatment was performed in the other bone. The mean time between the original injury and the indexed procedure was 7 months (3–14 months). The mean bone defect was 4 cm (2–6 cm). A T-shaped cortico-cancellous graft was always used. All the patients were evaluated clinically and radiographically with a mean follow-up of 4 years (1–10 years). Bony union was achieved in all the patients at an average time of 4 months (3–6 months). At the follow-up the mean elbow flexion was 130°, the mean extension lag 4°, the mean pronation 71° and the mean supination 61°. The mean grip strength was 38 kg, 81% of the contralateral side. Cortico-cancellous bone graft from the iliac crest is an effective technique to fill a bone defect of between 2 and 6 cm. Up to this length the mechanical properties of the graft are optimal for a rigid plate fixation under compression; moreover, biological conditions allow ready integration of the graft. Rigid fixation with cortico-cancellous bone graft from the iliac crest is a useful technique for forearm non-unions with a bone defect of between 2 and 6 cm

Aim: The aim of this investigation was to determine how the rotational axis of the wrist moves as the hand goes from full ulna to full radial deviation. Materials & Methods: Ulna to radial deviation was assessed in 30 normal wrists in 15 normal subjects aged 19 to 32. Movement was measured with a Polhemus Fastrak (TM) magnetic tracking system. The system has translational and rotational measurement accuracies of 1 mm and 1 degree respectively. Subjects placed their palms on a flat wooded stool and had movement sensors attached over their 3rd metacarpal and distal radius. These sensors then recorded movement as the hand moved from full ulna to full radial deviation. Results: The mean range of movement was 47 degrees (SD 8). In full ulna deviation the wrist rotational axis was in the region of the lunate/capitate. As the hand moved towards radial deviation, the axis moved distally. At the end of the movement the mean distal displacement was 22 mm (SD 14). In 17 wrists the distal displacement was accompanied by mean displacement towards the ulna of 13 mm (SD 8). In 13 wrists the distal displacement was accompanied by a mean displacement towards the radius of 7 mm (SD 5). Conclusion: The rotational axis position indicates how the wrist is moving during radial deviation. In early movement, when the axis is proximal, there is a high degree of sideways translation. In later movement, when the axis is distal, there is more rotational movement. In some cases the axis moved distally and toward the radius, whereas in other cases it moved distally and toward the ulna. This spectrum of movement may support the theory of 2 type of carpal movement. i.e. Column movers and row movers [Craigen & Stanley]

Aim: The carpal bone arrangement can be described as a matrix of two rows and three columns. There a various theories as to how the bones within the matrix move during ulna to radial deviation. One theory suggests that there are two types of wrist movement, namely Row & Column. 1. . The aim of this study was to investigation how the rotational axis of the wrist moves as the hand goes from full ulna to full radial deviation. Materials and Methods: Ulna to radial deviation was assessed in 50 normal wrists in 25 normal subjects aged 19 to 57. Movement was measured with a Polhemus Fastrak (TM) magnetic tracking system. The system has translational and rotational measurement accuracies of 1 mm and 1 degree respectively. Subjects placed their palms on a flat wooded stool and had movement sensors attached over their 3rd metcarpal and distal radius. These sensors then recorded movement as the hand moved from full ulna to full radial deviation. Results: The mean range of movement was 45 degrees (SD 7). In full ulna deviation the wrist rotational axis was in the region of the lunate. As the hand moved towards radial deviation, the axis moved distally. At the end of the movement the mean distal displacement was 21 mm (SD 15). In 32 wrists the distal displacement was accompanied by mean displacement towards the ulna of 12 mm (SD 8). In 18 wrists the distal displacement was accompanied by a mean displacement towards the radius of 8 mm (SD 5). Conclusion: The rotational axis position indicates how the wrist is moving during radial deviation. In early movement, when the axis is proximal, there is a high degree of sideways translation. In later movement, when the axis is distal, there is more rotational movement. In some cases the axis moved distally and toward the radius, whereas in other cases it moved distally and toward the ulna. This spectrum of movement may support the theory of 2 types of carpal movement. i.e. Column movers and row movers. 1.

Ulna Styloid Fractures have been historically dismissed as a relatively benign injury. However recent clinical and biomechanical research has suggested that primary repair of displaced ulna styloid avulsion fractures is advised as a means of stabilizing the radioulnar joint and preventing the disability associated with chronic radioulnar joint instability. Optimum fixation method was examined in this study using a human cadaveric model. A custom jig was designed to allow testing in radial/ulna deviation in varying degrees of wrist flexion and extension. Universal materials testing device was used to apply a maximum load of 150 N. Eight pairs of cadaveric wrists were tested. Constructs tested were 1.6mm K-wire fixation, Tension Band wiring and Screw Fixation. Fracture displacement was measured using a venire micrometer. Results: Displacement on forced radial deviation was maximum in neutral wrist position in all construct configurations. Displacement was minimized in 20 degrees wrist flexion. The optimum fixation method was 2 k-wires with tension band wiring. This study would suggest that the optimum fixation for ulna styloid fractures is a Tension band-wiring construct. If non-operative treatment is used we suggest that the wrist is immobilized in a position of wrist flexion to reduce tension on the ulna carpal ligament and prevent fracture displacement

The Madelung deformity can result in pain and decreased function of the wrist and hand. None of the surgical techniques available has been shown consistently to improve grip strength, range of movement or relieve pain. In this prospective study we have treated 18 patients with the Madelung deformity (25 wrists) by wedge subtraction osteotomy of the radius and shortening of the ulna. Our results show statistically significant improvement in grip strength and range of movement of the wrist and forearm. Pain improved in 80% of the patients and 88% were satisfied with the appearance. One patient had a wound infection and another developed reflex sympathetic dystrophy. Two had some recurrence due to continued growth of the ulna and it is recommended that the procedure be delayed until skeletal maturity, or else combined with epiphysiodesis of the ulna

The aim of this study was to investigate how the rotational axis of the wrist moves as the hand goes from full ulna to full radial deviation. Fifty normal wrists in 25 subjects were assessed with a Polhemus Fastrak (TM) magnetic tracking system. The subjects, aged 19 to 57, placed their palms on a flat wooded stool. Sensors were attached over their 3rd metcarpal and distal radius. The sensors then recorded movement from ulna to radial deviation. The translational and rotational measurement accuracies were 1 mm and 1 degree respectively. The mean range of movement was 45 degrees (SD 7). In ulna deviation the axis was in the region of the lunate. As the hand moved towards radial deviation, the axis moved distally. At the end of the movement the mean distal displacement was 21 mm (SD 15). In 32 wrists the distal displacement was accompanied by a mean displacement towards the ulna of 12 mm (SD 8). In 18 wrists the distal displacement was accompanied by a mean displacement towards the radius of 8 mm (SD 5). The rotational axis position indicates how the wrist is moving during radial deviation. In early movement, when the axis is proximal, there is a high degree of sideways translation. In later movement, when the axis is distal, there is more rotational movement. In some cases the axis moved distally and toward the radius, whereas in other cases it moved distally and toward the ulna. This spectrum of movement may support the theory of 2 types of carpal movement proposed by Craigen and Stanley (J. Hand Surg, 20B, 165–170, 1995)

Aims:. 1) To determine the predictive value of a simple stability test in children’s wrist fractures treated with simple manipulation and plaster of Paris (PoP) cast immobilisation. 2) To determine the effect of cast quality as reflected in the skin cast distance (distance between the cast and the skin in the plane of major displacement or angulation) and the cast index (the inside diameter of the cast in the sagittal plane divided by the inside diameter in the coronal plane) on re-displacement rates in children’s wrist fractures treated with simple manipulation and plaster of Paris (PoP) cast immobilisation. Methods: This is a prospective study of 57 children aged 4 to 15 with metaphyseal and Salter-Harris II wrist fractures treated with simple manipulation. Under fluoroscopic imaging, a simple stability test involving moving the hand at the wrist in the dorsopalmar, and radioulnar planes was performed following reduction, and x-ray images were saved. We recorded and compared the displacement and angulation on the initial x-rays, during the test, and at one-and 6-week follow-up. We also recorded the skin-cast distance (SCD), and the cast index (CI). Results: 38 patients had isolated radius fractures and 19 had radius and ulna fractures. Four patients needed remanipulation with K-wire fixation. Multiple regression analysis revealed significant correlation between percentage loss of reduction on testing and subsequent re-displacement (relationship between the two sets of values r = 0.6167, (p< 0.001)). This indicates that instability on testing (seen as a significant percentage loss of reduction) is likely to be associated with some loss of reduction on follow-up. There was a significant relationship between the skin cast distance and the cast index, and loss of reduction on one week follow-up. (p=0.006). Isolated radius fractures had a higher risk of re-displacement than radius and ulna fractures (3.9% and 0.9% respectively; p< 0.05%). Conclusion: Stable reduction on stability testing in wrist fractures in children immobilised in a good cast (reflected in a low SCD, and CI) is associated with a good outcome. Isolated radius and ulna fractures are more likely to re-displace than radius and ulna fractures. There is a relationship between instability and loss of position at the 1-week follow-up. Potentially unstable fractures can be prevented from slipping by a good cast. A stable fracture on our stability test rarely slips. We therefore feel that stability test is a useful adjunct in decision-making

Purpose of Study:. To review the outcome of paediatric patients with radius and ulna fractures treated with titanium elastic nails. Description of methods:. Paediatric patients with radius and ulna fractures who fulfilled the criteria for TENS nailing were used. The criteria included failed closed reduction, instability (>15°angulation, >5°rotation) and open fractures. The patients were treated with retrograde TENS nailing of the radius and ulna. The patients were followed up at a paediatric orthopaedic outpatient clinic at 1, 3, 6 and 12 weeks with a final visit at 6 months. Data was collected at every visit looking at range of motion (pronation and supination), clinical and radiological signs of union and complications. Summary of results:. Over a 16 month period, 214 paediatric patients with radius and ulna fractures were seen and managed. Eleven of these patients were treated with TENS nails. The average age of the patient was 8.3 years. The average time to union was 8.5 weeks. The average range of motion at 6 months was pronation of 80°and supination of 73°. Two patients developed a compartment syndrome in the immediate post-operative period and were treated with a fasciotomy and skin grafting. No other complications were noted. Conclusion:. TENS nailing of paediatric radius and ulna fractures in unstable, irreducible and open fractures is a good treatment modality with good, early union of fractures and acceptable range of motion. It provides an excellent alternative to plating these fractures

The results of excision of the distal ulna in 34 wrists of 25 patients with chronic rheumatoid arthritis of the distal radio-ulnar joint were reviewed. Rest pain had been cured or relieved in 77%, pain on pronation-supination in 86%, and limitation of pronation-supination in 90%, while 88% of the patients graded the result as excellent or fair. Despite this marked relief of symptoms, function of the upper limb was improved in only 25% of patients and remained unchanged in 60%. Ulnar subluxation of the carpus had occurred in 24% but seemed to be related to the destructive disease process rather than to the operation itself. The length of ulna resected was not related to the outcome of the operation

The integrity of the periosteum and the interosseous membrane determine the stability of fractures of the distal ulna; this is indicated by the initial displacement. In fractures displaced by less than 50% the periosteum and interosseous membranes are largely intact; these fractures are stable and require only below-elbow immobilisation for protection and relief of pain. In fractures displaced by more than 50% the membranes are disrupted; these fractures are unstable and require above-elbow immobilisation for stability. As most fractures are displaced by less than 50%, immobilisation of the elbow, which significantly increases morbidity, is usually unnecessary. I report the results of a cadaveric study on the pathomechanics of fractures of the distal ulna, and of a prospective clinical trial in which the type of cast used for immobilisation was determined by the stability of the fracture

After a fracture of the distal radius, the bone segments may heal in a suboptimal position. This condition may lead to a reduced hand function, pain and finally osteoarthritis, sometimes requiring corrective surgery. The contralateral unaffected radius is often used as a reference in planning of a corrective osteotomy procedure of a malunited distal radius. In the conventional procedure, radiographs of both the affected radius and the contralateral radius have been used for planning. The 2D nature of radiographs renders them sub-optimal for planning due to overprojection of anatomical structures. Therefore, computer-assisted 3D planning techniques have been developed recently based on CT images of both forearms. The accuracy of using the contralateral forearm for CT based 3D planning the surgery of the affected arm and the optimal strategy for planning have not been studied thoroughly. To estimate the accuracy of the planned repositioning using the contralateral forearm we investigated bilateral symmetry of corresponding radii and ulnae using 3-dimensional imaging techniques. A total of 20 healthy volunteers without previous wrist injury underwent a volumetric computed tomography scan of both forearms. The left radius and ulna were segmented to create virtual 3 dimensional models of these bones. We selected a distal part and a larger proximal part from these bones and matched them with a mirrored CT-image of the contralateral side. This allowed estimation of the accuracy by calculation of relative displacements (Δx, Δy, Δz) and rotations (Δψx, Δψy, Δψz) required to align the left bone with the right bone segments as a reference. We also investigated the relationship between longitudinal length differences in radius and ulna and utilised this relationship to arrive at an optimal planning of the length of the affected radius after surgery. Relative differences in displacement and orientation parameters after planning based on the contralateral radius were (Δx, Δy, Δz): −0.81±1.22 mm, −0.01±0.64 mm, and 2.63±2.03 mm; and (Δψx, Δψy, Δψz): 0.13°±1.00°, −0.60°±1.35°, and 0.53°±5.00°. The same parameters for the ulna were (Δx,Δy, Δz): −0.22±0.82 mm, 0.52±0.99 mm, 2.08±2.33 mm; and (Δψx, Δψy, Δψz): −0.56°±0.96°, −0.71°±1.51°, and −2.61°±5.58°. The results also point out that there is a strong linear relationship between absolute length differences (Δz) of the radius and ulna among the individuals. Since we observed substantial length difference of the longitudinal bone axes of both forearms in healthy individuals, including the length difference of the adjacent forearm bones in the planning turned out to be useful in improving length correction in computer-assisted planning of radius or ulna osteotomies. The improved planning markedly reduces length positioning variability, (from 2.9± 2.1 mm to 1.5 ± 0.6 mm). We expect this approach to be valuable for 3-D planning of a corrective distal radius osteotomy. Awareness of the level of bilateral symmetry is important in reconstructive surgery procedures when the contralateral unaffected side is used as a reference for planning and evaluation. Bilateral asymmetry may introduce length errors into this type of preoperative planning that can be reduced by taking into account the concomitant ulnae asymmetry

Stress shielding (i.e. reduction in bone strains) in the distal ulna is commonly noted following ulnar head replacement arthroplasty. Optimal design parameters for distal ulnar implants, including the length of the stem, are currently unknown. The purpose of this study was to investigate the effect of stem length on bone strains along the length of the ulna. Strain gauges were applied to each of eight cadaveric ulnae to measure bending loads at six locations along each ulna’s length (approximately 1.5, 2.5, 4.0, 6.0, 8.0, and 13.0cm from the ulnar head). The proximal portion of each bone was secured in a custom-designed jig. A materials testing machine applied loads (5–30N) to the ulnar head while native strains were recorded. The ulnar head was removed and the loading procedure repeated for cemented stainless steel stems 3 and 7cm in length, according to a previously reported technique (Austman et al, CORS 2006). Other stem lengths between 3 and 7cm were tested in 0.5cm intervals with a 20N load applied only. Data were analyzed using a two-way repeated measures ANOVA (á=0.05). In general, distal bone strains increased as stem length decreased (e.g. average microstrains at the second distal-most gauges: 138±13 (7cm), 147±15 (6cm), 159±21 (5cm), 186±40 (4cm), 235±43 (3cm)). The native strains were different from all stem lengths for the four distal-most gauges (p< 0.05). No differences were found between any stem length and the native bone at the two proximal-most gauges. The 3cm stem replicated the native strains more closely than the 7cm, over all applied loads (e.g. average microstrains at the third gauge level for a 25N load: 357±59 (native), 396±74 (3cm), 257±34 (7cm)). No stem length tested matched the native strains at all gauge locations. The 3cm stem results were closer to the native strains than the 7cm stem for all loads at gauges overtop of the stem. Overall, the 3cm stem produced the highest strains, and thus would likely result in less distal ulnar bone resorption after implantation. These results suggest that shorter (approximately 3cm) stems should be considered for distal ulnar implants to potentially reduce stress shielding, although this must be balanced by adequate stem length for fixation