Evaluation of mushroom-shaped allograft for unstable proximal humerus fractures.

INTRODUCTION: Proximal humerus fractures are common injuries of the elderly. Different treatment options, depending on fracture complexity and stability, have been recommended in the literature. Particularly for varus displaced fractures with a lack of medial support, and patients suffering from osteoporosis, structural allografts can be used to enhance the stability of the construct. An individually shaped allograft has been suggested in the literature and investigated in a clinical setting. However, biomechanical properties have yet to be evaluated. MATERIALS AND METHODS: Twenty-four fresh-frozen humeri and 12 femoral heads were obtained, and an unstable three-part fracture of the humeral head was simulated. Fracture fixation was achieved by using a locking plate in both groups. In the test group, a mushroom-shaped allograft was tailored out of a femoral head to individually fit the void inside the humeral head. Specimens were fitted with a 3D motion analysis system and cyclically loaded with a stepwise increasing load magnitude in a varus-valgus bending test until failure or up to a maximum of 10,000 load cycles. RESULTS: The mushroom group reached a significantly higher number of load cycles (8342; SD 1,902; CI 7133-9550) compared to the control group (3475; SD 1488; CI 2530-4420; p < 0.001). Additionally, the test group showed significantly higher stiffness values concerning all observational points (p < 0.001). CONCLUSION: This mushroom-shaped allograft in combination with a locking plate significantly increased load to failure as well as stiffness of the construct when exposed to varus-valgus bending forces. Therefore, it might be a viable option for surgical treatment of unstable and varus displaced proximal humerus fractures to superiorly prevent loss of reduction and varus collapse.

The female geriatric proximal humeral fracture: protagonist for straight antegrade nailing?

INTRODUCTION: Straight antegrade humeral nailing (SAHN) has become a standard technique for the surgical fixation of proximal humeral fractures, which predominantly affect elderly females. The nail's proximal anchoring point has been demonstrated to be critical to ensure reliable fixation in osteoporotic bone and to prevent iatrogenic damage to the superior rotator cuff bony insertion. Anatomical variations of the proximal humerus, however, may preclude satisfactory anchoring of the nail's proximal end and may bare the risk of rotator cuff violation, even though the nail is inserted as recommended. The aim of this study was to evaluate the anatomical suitability of proximal humeri of geriatric females aged 75 years and older for SAHN. Specifically, we sought to assess the proportion of humeri not anatomically amenable to SAHN for proximal humeral fracture. MATERIALS AND METHODS: A total of 303 proximal humeri of 241 females aged 75 years and older (mean age 84.5 ± 5.0 years; range 75-102 years) were analyzed for this study. Multiplanar two-dimensional reformations (true ap, true lateral, and axial) were reconstructed from shoulder computed tomography (CT) data sets. The straight antegrade nail's ideal entry point, "critical point" (CP), and critical distance (CD; distance between ideal entry point and CP) were determined. The rate of proximal humeri not anatomically suitable for SAHN (critical type) was assessed regarding proximal reaming diameters of currently available straight antegrade humeral nails. RESULTS: Overall, 35.6% (108/303) of all proximal humeri were found to be "critical types" (CD <8 mm) as to the recommended minimal proximal reaming diameter of 10 mm of straight antegrade nails currently in use. Moreover, 43.2% (131/303) of the humeri were considered "critical types" with regard to the alternatively used larger proximal reaming diameter of 11.5 mm. Mean CD was 9.0 ± 1.7 mm (range 3.5-13.5 mm) and did not correlate with age (r = -0.04, P = 0.54). No significant differences in CD and rate of "critical types" were found between left and right humeri as well as between females aged between 75 and 84 years (n = 151) and females aged 85 and older (n = 152). CONCLUSIONS: More than a third of proximal humeri of geriatric females are "critical types" as to SAHN and may, therefore, be at risk for procedure-related complications, such as rotator cuff violation, fixation failure, and potential malreduction. In view of this finding, we recommend to routinely analyze multiplanar CT reformations of the uninjured contralateral side prior to surgery to improve selection of patients for SAHN and to minimize foreseeable complications. For "critical type" humeri, an alternative surgical procedure should be considered.

Biomechanical evaluation of straight antegrade nailing in proximal humeral fractures: the rationale of the "proximal anchoring point".

PURPOSE: Varus failure is one of the most common failure modes following surgical treatment of proximal humeral fractures. Straight antegrade nails (SAN) theoretically provide increased stability by anchoring to the densest zone of the proximal humerus (subchondral zone) with the end of the nail. The aim of this study was to biomechanically investigate the characteristics of this "proximal anchoring point" (PAP). We hypothesized that the PAP would improve stability compared to the same construct without the PAP. METHODS: Straight antegrade humeral nailing was performed in 20 matched pairs of human cadaveric humeri for a simulated unstable two-part fracture. RESULTS: Biomechanical testing, with stepwise increasing cyclic axial loading (50-N increments each 100 cycles) at an angle of 20° abduction revealed significantly higher median loads to failure for SAN constructs with the PAP (median, 450 N; range, 200-1.000 N) compared to those without the PAP (median, 325 N; range, 100-500 N; p = 0.009). SAN constructs with press-fit proximal extensions (endcaps) showed similar median loads to failure (median, 400 N; range, 200-650 N), when compared to the undersized, commercially available SAN endcaps (median, 450 N; range, 200-600 N; p = 0.240). CONCLUSIONS: The PAP provided significantly increased stability in SAN constructs compared to the same setup without this additional proximal anchoring point. Varus-displacing forces to the humeral head were superiorly reduced in this setting. This study provides biomechanical evidence for the "proximal anchoring point's" rationale. Straight antegrade humeral nailing may be beneficial for patients undergoing surgical treatment for unstable proximal humeral fractures to decrease secondary varus displacement and thus potentially reduce revision rates.

Does intra-articular load distribution change after lateral malleolar fractures? An in vivo study comparing operative and non-operative treatment.

PURPOSE: The impact of isolated malleolar fractures on the intra-articular load distribution within the ankle joint has been studied in several biomechanical cadaver studies during the last decades. Recently, computed tomography osteoabsorptiometry (CT-OAM) has been proposed as a valuable tool to assess intra-articular joint load distribution in vivo. The purpose of this retrospective matched pair analysis was to apply CT-OAM to evaluate in vivo changes of talar load distribution after lateral malleolar fractures in patients treated with open anatomic reduction and internal fixation (ORIF) compared to patients treated non-operatively. METHODS: Ten matched pairs of patients with isolated lateral malleolar fractures with a maximum fracture dislocation of 3mm and a median follow-up of 42 month were included into the study. Patients were matched for age, gender, and fracture dislocation. Range of ankle motion (ROM), the AOFAS hindfoot score and the Short Form 36 (SF-36) were evaluated. CT-OAM analysis of the injured and the uninjured contralateral ankles were performed. RESULTS: Patients treated with ORIF showed a significant lower ROM compared to the uninjured contralateral ankle. No differences were found regarding clinical scores between patients treated by ORIF and those treated non-operatively. CT-OAM analysis showed symmetrical distribution of subchondral bone mineralization in comparison to the uninjured contralateral ankles for both groups of patients. CONCLUSIONS: The data of this study suggest that isolated lateral malleolar fractures with fracture gaps up to 3mm are not associated with a change of the tibio-talar joint load distribution in vivo. Therefore, patients with isolated minimally displaced lateral malleolar fractures may achieve good clinical long-term outcome following non-operative treatment. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Computed tomography-based prediction of the straight antegrade humeral nail's entry point and exposure of "critical types": truth or fiction?

BACKGROUND: Straight antegrade intramedullary nailing of proximal humerus fractures has shown promising clinical results. However, up to 36% of all humeri seem to be "critical types" in terms of the potential violation of the supraspinatus (SSP) tendon footprint by the nail's insertion zone. The aims of this study were to evaluate if a computed tomography (CT) scan could reliably predict the nail's entry point on the humeral head and if it would be possible to preoperatively estimate the individual risk of iatrogenic violation of the SSP tendon footprint by evaluating the uninjured contralateral humerus. METHODS: Twenty matched pairs of human cadaveric shoulders underwent CT scans, and the entry point for an antegrade nail as well as measurements regarding critical distances between the entry point and the rotator cuff were determined. Next, gross anatomic measurements of the same data were performed and compared. Furthermore, specimens were reviewed for critical types. RESULTS: Overall, 42.5% of all specimens were found to be critical types. The CT measurements exhibited excellent intra-rater and inter-rater reliability (intraclass correlation coefficients >0.90). Similarly, excellent agreement between the CT scan and gross anatomic measurements in contralateral shoulders (intraclass correlation coefficients >0.88) was found. CONCLUSION: Assessing the uninjured contralateral side, CT can reliably predict the entry point in antegrade humeral nailing and preoperatively identify critical types of humeral heads at risk of iatrogenic implantation damage to the SSP tendon footprint. This study may help surgeons in the decision-making processon which surgical technique should be used without putting the patient at risk for iatrogenic, implant-related damage to the rotator cuff.

The J-Shaped Bone Graft for Anatomic Glenoid Reconstruction: A 10-Year Clinical Follow-up and Computed Tomography-Osteoabsorptiometry Study.

BACKGROUND: The J-shaped bone graft procedure is one of the recommended methods to reconstruct significant glenoid rim defects. PURPOSE: To evaluate long-term (minimum 10-year) clinical outcomes and show further details of the remodeling effects on the articular cavity of the glenoid after J-shaped bone grafting. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 14 patients treated with a J-shaped bone graft procedure were observed clinically. Additionally, bilateral preoperative and postoperative follow-up computed tomography (CT) scans were used for CT-osteoabsorptiometry (OAM) to evaluate the bony remodeling processes. RESULTS: The follow-up rate was 93% at a mean follow-up time of 10.7 years (range, 10.08-11.75 years). Patients exhibited a mean Constant score of 92.5 (range, 80-100) on the clinical evaluation. All patients had free range of motion and were pain free without any recurrence of instability. Based on CT-OAM, comparable and almost anatomically reconstructed, bilaterally equal glenoid cavities were found postoperatively. The distribution patterns of glenoid subchondral mineralization were bilaterally equal in 85.7% of the patients. CONCLUSION: The surgical treatment of recurrent shoulder instability with a significant bony Bankart lesion using the J-shaped bone graft procedure provided excellent long-term results. This study lends evidence to support the capability of the J-shaped bone graft procedure to restore the normal glenoid shape due to physiological remodeling processes.

Predictors for satisfaction after anatomic total shoulder arthroplasty for idiopathic glenohumeral osteoarthritis.

INTRODUCTION: The use of total shoulder arthroplasty (TSA) to treat primary glenohumeral osteoarthritis (GHOA) is increasing. Factors influencing patient satisfaction after surgery have not been well documented. The aim of this study was to determine demographic, radiologic, and surgical, factors predictive for satisfaction after TSA for GHOA. MATERIALS AND METHODS: Between 2005 and 2012, 95 shoulders undergoing TSA for GHOA by a single surgeon were eligible for inclusion in the study. Age, gender, previous surgeries, American Society of Anesthesiologists (ASA) score, and Walch glenoid morphology were analyzed as satisfaction predictors. Patients with Walch glenoid type C were excluded. RESULTS: Data on 80/92(87 %) shoulders were available at a mean of 3 years (range 2-9). Three complications (3 %) and 2 failures (2 %) occurred. The outcome scores collected significantly improved from preoperative values (p < 0.05). Median patient satisfaction was 10/10. Gender, age, previous surgery, ASA score, and Walch morphology were not associated with patient satisfaction. CONCLUSIONS: TSA provided excellent results for patients with idiopathic GHOA with low complication and failure rates. Outcomes after TSA for type B glenoid morphology with posterior subluxation were similar to outcomes after TSA for centered type A morphology. Overall patient satisfaction was high and was not influenced by the demographic, anatomic, and surgical variables investigated. LEVEL OF EVIDENCE: III, Therapeutic study, Retrospective Cohort Study.

Chronic rupture of the long head of the biceps tendon: comparison of 2-year results following primary versus revision open subpectoral biceps tenodesis.

INTRODUCTION: The purpose of this study was to evaluate the clinical results of surgical repair for proximal long head of the biceps (LHB) tendon ruptures comparing chronic primary and postsurgical revision LHB tendon ruptures. MATERIALS AND METHODS: Patients who underwent subpectoral LHB tenodesis for chronic ruptures with a minimum of 2 years from surgery were identified. ASES and SF-12 PCS scores and surgical and demographic data were collected prospectively. At final follow-up, patients were interviewed regarding symptoms related to their biceps. Symptoms were converted into a Subjective Proximal Biceps Score (SPBS). RESULTS: Twenty-seven patients (22 males, 5 females) with a mean age of 61 years (range 40-76 years) underwent LHB tenodeses. Twenty patients (74.1 %) were primary repairs for chronic ruptures and seven patients (25.9 %) were revision repairs after failed prior LHB tenodesis. Twenty-five patients (92.6 %; n = 18 primary; n = 7 revision) were available for follow-up a mean of 3.8 years (range 2-6.1). The overall median postoperative SPBS showed significant improvement over the preoperative baseline (p < 0.001). Individual components of the SPBS showed substantial improvements. The SPBS significantly correlated with the postoperative ASES score (r = -0.478; p = 0.038). There were no differences in postoperative SPBSs between the primary and revision tenodesis groups. The mean postoperative ASES score was 90.3 and SF-12 PCS was 52.6. CONCLUSIONS: Open subpectoral LHB tenodesis was a safe and effective method for the treatment of chronic LHB tendon ruptures and for the revision of failed post-surgical LHB ruptures. Patients had less pain, cramping, and deformity after LHB tenodesis. The SPBS, ASES, and SF-12 PCS scores significantly improved among this group of patients. LEVEL OF EVIDENCE: Level III; Retrospective comparative study.

The relevance of neutral arm positioning for true ap-view X-ray to provide true projection of the humeral head shaft angle.

INTRODUCTION: Textbooks commonly recommend using the true anterior-posterior (ap)-view with the patient's arm in a sling and therefore in internal rotation (IR) for radiologic diagnostic assessment of the proximal humerus after trauma. However, IR or external rotation (ER) may affect the projection of the head shaft angle (HSA) and therefore bias the diagnostic conclusion significantly. We hypothesized that neutral rotation (NR) of the arm is mandatory for true ap-view to provide true projection of the HSA. MATERIALS AND METHODS: A simplified geometrical model of the proximal humerus was used to examine the influence of different arm positions and angulations of the central ray in relation to the projection of the HSA. RESULTS: Both ER and IR misleadingly suggested an increased valgus angle. Simulating the true ap-view with the central ray in cranio-caudal direction, IR changed the projection of the HSA substantially. CONCLUSION: In conclusion, standard fixation of the patient's arm in a shoulder sling in IR for true ap-view may result in an oblique projection, potentially leading to incorrect surgical implications. To prevent misdiagnosed valgus or varus angulation, NR of the arm should be obeyed when performing true ap-view X-ray. We, therefore, highly recommend to overcome the traditionally arm position, ensuring the true amount of dislocation to assure correct surgical implications and comparable follow-up examinations.

The ability of massive osteochondral allografts from the medial tibial plateau to reproduce normal joint contact pressures after glenoid resurfacing: the effect of computed tomography matching.

BACKGROUND: Current techniques for resurfacing of the glenoid in the treatment of arthritis are unpredictable. Computed tomography (CT) studies have demonstrated that the medial tibial plateau has close similarity to the glenoid. The purpose of this study was to assess contact pressures of transplanted massive tibial osteochondral allografts to resurface the glenoid without and with CT matching. METHODS: Ten unmatched cadaveric tibiae were used to resurface 10 cadaveric glenoids with osteochondral allografts. Five cadaveric tibiae and glenoids were CT matched and studied. An internal control group of 4 matched pairs of glenoids, with the contralateral glenoid transplanted to the opposite glenoid, was also included as a best-case scenario to measure the effects of the surgical technique. All glenoids were tested before and after grafting at different abduction and rotation angles, with recording of peak contact pressures. RESULTS: Peak contact pressures were not different from the intact state in the autografted group but were increased in both allografted groups. CT-matched tibial grafts had lower peak pressures than unmatched grafts. Peak pressures were on average 24.8% (range [18.3%, 29.6%]) greater than in the native glenoids for unmatched allografts, 21.8% ([17.0%, 25.5%]) greater for the matched allografts, and 4.9% ([3.8%, 5.5%]) greater for matched autografts. CONCLUSION: Osteochondral grafting from the medial tibial plateau to the glenoid is feasible but results in increased peak contact pressures. The technique is reproducible as defined by the autografted group. Contact pressures between native and allografted glenoids were significantly different. The clinical significance remains unknown. Peak pressures experienced by the glenoid seem highly sensitive to deviations from the native glenoid shape.

Biomechanical analysis of subpectoral biceps tenodesis: effect of screw malpositioning on proximal humeral strength.

BACKGROUND: Humeral fracture after subpectoral tenodesis of the long head of biceps tendon (LHB) is a rare but devastating complication. PURPOSE: To determine whether malpositioned (laterally eccentric) tenodesis screw placement has an influence on humerus strength reduction compared with central placement. STUDY DESIGN: Controlled laboratory study. METHODS: Two groups, each consisting of 10 matched pairs of human humeri, were used for this study. Biceps tendons were fixed subpectorally with 8-mm screws in unicortical 8-mm sockets. In the first group, the socket was placed concentrically in the bicipital groove and the tendon was fixed with an interference screw. In the second group, the socket was malpositioned 30% eccentrically to the lateral (tension) side of the humerus. Contralateral humeri remained intact as positive controls. Specimens were aligned in 40° of abduction, and a uniaxial compressive force was applied to the humeral head until failure. Strength reduction was reported as percentage reduction in ultimate failure load between paired humeri. Relative defect size was calculated as a percentage of the total humeral width at the height of the tenodesis. RESULTS: Laterally eccentric malpositioned biceps tenodeses significantly decreased humeral strength compared with intact (mean change, -25%; SD, 23%; P=.017), while concentrically placed biceps tenodeses did not (mean change, -10%; SD, 15%; P=.059). A linear regression between relative defect size and strength reduction in the malpositioned group showed a significant negative linear correlation (beta=-2.577; R2=0.423; P=.042). CONCLUSION: Humeral fracture after subpectoral tenodesis of the LHB is a complication that may be minimized with careful surgical technique. Laterally eccentric malpositioned biceps tenodesis caused significant reduction (25%) in humeral strength, which might be clinically relevant and contribute to postsurgical humeral shaft fracture. Strength reduction was also significantly correlated with relative defect size. Surgeons using this technique should ensure central and orthogonal placement of the socket, especially in smaller individuals. This study lends biomechanical evidence to support the clinical procedure of a correctly, concentrically placed tenodesis screw. CLINICAL RELEVANCE: These biomechanical results indicate that in a clinical setting, special attention should be drawn to patient selection for LHB tenodesis. This study reveals that central screw positioning is critical, particularly in high-impact and overhead athletes, as well as for patients with small humeral widths or osteoporotic bone quality. Alternative surgical options such as smaller screws or other fixation methods might be considered to diminish the postoperative risk of humeral fracture.

Allogenic bone grafting for augmentation in two-part proximal humeral fracture fixation in a high-risk patient population.

INTRODUCTION: The surgical fixation of unstable, varus displaced two-part fractures of the proximal humerus remains challenging. MATERIALS AND METHODS: In a case series of 10 non-compliant, high-risk patients (median age 63 years; range 52-78), a cancellous allograft was used to augment plate fixation of the fractures. RESULTS: After a median follow-up of 28.5 months, all but one fracture were healed, with the bony allografts incorporated without any systemic or local complications. No significant loss of reduction or evidence of avascular necrosis of the humeral head was seen. The median Constant-Murley Score was 72.0 (range 45-86). Median pain on a visual analog scale was 1 (range 0-7). Median values for the range of motion were flexion: 155° (range 90-170), abduction: 168° (range 95-180) and external rotation: 43° (range: 30-50). Compared to the uninjured contralateral side, flexion was impaired by 13 %, abduction by 14 %, and external rotation by 15 %. Median abduction power was 64 % of the uninjured side. The median varus displacement was 51° (range 45-59) preoperatively, 4° (range -5 to 19) intraoperatively, and 13° (range 1-18) at the time of the final follow-up, relating to an improvement of 38° compared to the preoperative status. CONCLUSIONS: The augmentation of proximal humeral fracture fixation using a cancellous allograft might be a viable and reliable alternative to prevent early varus failure and to, moreover, lead to bony union in a non-compliant or high-risk patient population.

Biomechanical consequences of proximal biceps tenodesis stitch location: musculotendinous junction versus tendon only.

PURPOSE: The purpose of this study was to determine the biomechanical effects of placing the biceps tenodesis stitch at the musculotendinous junction versus in the tendon only. Placing the stitch at the musculotendinous junction was hypothesized to result in a significantly weaker repair than stitching in the tendon only. METHODS: Testing was performed on two groups of six matched pairs of long head of the biceps (LHB) with enclosed musculotendinous junction and muscle belly. Specimens were randomly distributed between two groups. The same baseball whipstitch configuration was performed using the same suture material in both groups. In group 1, the stitch configuration started 1 cm proximal of the musculotendinous junction (tendon tissue only). For contralateral specimens, the baseball whipstitching included the distal 1 cm of the musculotendinous junction. Specimens were pulled to failure at a rate of 60 mm/min. Ultimate failure load and failure pattern were recorded. RESULTS: Average ultimate failure load of group 2 was significantly higher than group 1 (mean increase 18.6 %, range -9.7 to 35.8 %; p = 0.046). A cut-through failure pattern was observed for all specimens in both groups. There were highly significant correlations between ultimate failure load and tendon thickness (p = 0.004, τ = 0.636), age of the specimen (p = 0.002, τ = 0.724), and gender (p = 0.004, τ = -0.739). No significant difference between the groups regarding tendon diameter was observed. CONCLUSIONS: Baseball whipstitching of the LHB including the distal part of the tendon and the musculotendinous junction was stronger than sutures placed in the tendon alone. These results suggest that suture pattern affects initial strength of repair, and therefore may affect decisions regarding early post-operative rehabilitation or ultimate clinical outcomes. Inclusion of the musculotendinous junction should be considered clinically for improved time zero strength of the repair construct.

The effect of delayed treatment on clinical and radiological effects of anterior wedge grafting for non-union of scaphoid fractures.

INTRODUCTION: The aim of the treatment of displaced scaphoid non-unions is the restoration of normal scaphoid anatomy. Restoration of normal scaphoid anatomy at an earlier stage might have functional benefits as maladaptive carpal ligament contractures and the development of preliminary osteoarthritis could be avoided. The purpose of this retrospective study was to determine if late reconstruction (delayed reconstruction group) was as effective as early reconstruction (early reconstruction group) of scaphoid non-union in restoring clinical and radiological outcome. PATIENTS AND METHODS: The early reconstruction group included patients who underwent surgery between 6 and 12 months after the original fracture. This group consisted of 14 male and 2 female patients. The delayed reconstruction group included patients who underwent surgery 12 or more months after the original fracture. This group consisted of 9 male and 1 female patients. Average time from injury to surgery in the early reconstruction group was 10 months (range 6-12 months) and mean postoperative follow-up period averaged 58 months (range 19-72 months). Average time from injury to surgery in the delayed reconstruction group was 69 months (range 12-88 months) and mean postoperative follow-up period averaged 62 months (range 24-80 months). All patients showed a humpback deformity as well as a DISI deformity with the radiolunate angle being greater than 15°. The outcome was assessed on the basis of measurement of active wrist range of motion and grip power. Wrist pain was evaluated using a visual analogue scale. Functional subjective outcome was evaluated with the DASH and PRWE scores. Results were compared to preoperative measurements as well as to the uninjured contralateral side. Pre- and post-operative radiographs were assessed for scapholunate angle (SLA) as a measure of palmar rotation and radiolunate angle (RLA). The presence of DISI was defined by a difference of >60° for the SLA or of >10° for the RLA between the affected and unaffected wrist. RESULTS: In the early reconstruction group bone union and correction of DISI deformity could be achieved for all patients (n = 16). In the delayed reconstruction group bone union could only be achieved without correction of the DISI deformity in six patients (60 %). In four patients (40 %) of the delayed reconstruction group non-union persisted. For the early reconstruction group at final follow-up mean flexion-extension arc, mean ulnar-radial-deviation arc and mean grip strength were 82, 91.5 and 82 % of uninjured side, respectively. Mean pain level decreased from 6 points before surgery to 1 point at final follow-up. The preoperative DASH changed from 48 to 17 and the preoperative PRWE changed from 30 to 14. The SLA changed from 51° to 48° and the RLA from 18° to 9°. Six patients from delayed reconstruction group showed bone union, but no correction of DISI deformity at final follow-up. Functional and radiological results showed only slight improvement. The remaining four patients from delayed reconstruction group with a persistent non-union continued to experience pain, reduced grip strength and limited range of wrist movement and DISI deformity persisted. CONCLUSION: In conclusion, wedge-shaped bone grafting of scaphoid non-union leads to increased functional scores as well as to improved carpal angles as long as bony union can be achieved. Remaining non-union and the inability to correct DISI deformity are severely correlated with an increased time frame between fracture and surgical treatment. Furthermore, the vascularization of the proximal fragment and patients' smoking habits has to be taken into consideration preoperatively.

Biomechanical Consequences of Coracoclavicular Reconstruction Techniques on Clavicle Strength.

BACKGROUND: Lateral clavicle fractures have been reported after coracoclavicular (CC) ligament reconstructions with bone tunnels through the clavicle. PURPOSE: To biomechanically compare clavicle strength following 2 common CC reconstruction techniques with different bone tunnel diameters. STUDY DESIGN: Controlled laboratory study. METHODS: Testing was performed on 2 groups of matched-pair cadaveric clavicles. Clavicles were prepared with either 2.4-mm tunnels and cortical fixation button (CFB) devices or 6.0-mm tunnels with hamstring tendon grafts (TGs) and tenodesis screws; contralateral clavicles were left intact. A 3-point bending load was applied to the distal clavicles at a rate of 15 mm/min until failure. Ultimate failure load and anterior-posterior width of the clavicles 45 mm medial from the lateral border were recorded. Strength reduction was determined as the percentage reduction in ultimate failure load between paired intact and surgically prepared clavicles. Relative tunnel size was determined as the quotient of tunnel diameter and clavicle width, reported as a percentage. RESULTS: The TG technique significantly reduced clavicle strength relative to intact (P = .011) and caused significantly more strength reduction (mean, -30.7%; range, 8.1% to -62.5%) than the CFB technique (mean, -3.8%; range, 34.2% to -28.1%; P = .031). The CFB technique was not significantly different from intact (P = .314). There was a significant correlation between clavicle width and strength reduction (τ = -0.36, P = .04) and between relative tunnel size and strength reduction (τ = 0.51, P = .005). CONCLUSION: The TG reconstruction technique with 6.0-mm tunnels, grafts, and tenodesis screws caused significantly more reduction of clavicle strength compared with the CFB technique with 2.4-mm tunnels and CFB device. Additionally, relative tunnel width correlated highly with the strength reduction. CLINICAL RELEVANCE: This information can influence intraoperative decision making based on the individual clavicle width and might influence postoperative treatment protocols. Large bone tunnels may predispose patients to clavicle fractures after anatomic CC reconstructions.

Engineering of vascularized transplantable bone tissues: induction of axial vascularization in an osteoconductive matrix using an arteriovenous loop.

INTRODUCTION: Vascularization remains an obstacle to engineering of larger volume bone tissues. Our aim was to induce axial vascularization in a processed bovine cancellous bone (PBCB) matrix using an arteriovenous (AV) loop (artery, vein graft, and vein). METHODS: Custom-made PBCB discs (9 x 5 mm) were implanted into rats. In group A (n = 19), the matrices were inserted into microsurgically constructed AV loops between the femoral vessels using a vein graft from the contralateral side. In group B (n = 19), there was no vascular carrier. The matrices were encased in isolation chambers. After 2, 4, and 8 weeks, the animals were perfused with India ink via the abdominal aorta. Matrices were explanted and subjected to histological and morphometric analysis. Results were compared with intravital dynamic micro & magnetic resonance imaging and scanning electron microscopy images of vascular corrosion replicas. RESULTS: In group A, significant vascularization of the matrix had occurred by the 8th week. At this time, vascular remodeling with organization into vessels of different sizes was evident. Blood vessels originated from all 3 zones of the AV loop. Group A was significantly superior to group B in terms of vascular density and vascularization kinetics. DISCUSSION: This study demonstrates for the first time successful vascularization of solid porous matrices by means of an AV loop. Injection of osteogenic cells into axially prevascularized matrices may eventually create functional bioartificial bone tissues for reconstruction of large defects.