Isolated Greater Tuberosity (GT) fractures were described as separate entities from proximal humeral fractures more than 100 years ago. However, there is limited literature available about the functional outcome of the two different types of GT fractures: avulsed and comminuted. To compare functional outcomes of the 2 different types of Greater Tuberosity fractures; simple and comminuted and to determine how these outcomes were affected by associated injuries such as shoulder dislocation and rotator cuff tear. We also looked at the acceptable post fixation displacement of GT fracture and when to consider it mal-reduction (malunion due to over or under reduction) and the acceptable time frame to delay the fixation and still get satisfactory results. We looked at Greater Tuberosity fractures of the humerus in Waikato Hospital between 1999–2009. Radiographs were reviewed by senior Author to classify them into simple and comminuted. Measurements were done by senior Author for post fixation displacement. Operative notes checked by the authors, when in doubt, double-checked by senior author. Outcome scores used: UCLA, ASES and oxford scores to compare functional outcome. We also measured the time off work and time on ACC (Physiotherapy), as well as period of follow up. A total of 35 patients were included in the final analysis were treated operatively. Mean age of the patients was 51 years. M/F ratio was 3/2. Mechanism of injury was predominantly direct force applied to that shoulder. Shoulder dislocation was found in around 77% of patients. Methods of fixation included tension band wiring with or without screws, rotator cuff repair and one T-plate. Follow up time was shorter for simple comminuted fractures (22 v 44 weeks respectively). Outcome scores for patients who sustained simple fractures were slightly higher than those with comminuted fractures but the difference did not reach statistical significance. The groups with dislocation and rotator cuff tear did worse than the other groups in all aspects of the study. Post fixation displacement of GT of less than 5 mm led to a significantly better outcome than displacement of 5mm plus. Better results were obtained when the time between injury and operation was less than 2 weeks. The comminuted group had similar functional outcome to the other group but required much longer follow up. Worse outcome should be expected with dislocation and rotator cuff tear associated with GT fracture. Satisfactory results relate to degree of displacement post fixation of <5 mm. Delay of fracture fixation of >2 weeks results in a less favourable outcome

Medial transfer of the tibial Tuberosity remains the treatment of choice for skeletally mature patients with patellar malalignment (recurrent dislocation, subluxation with or without patellar tilt). As many patients with patellar malalignment have patellar articular cartilage lesion or patella alta, anteriorisation and distalisation of the tibial tuberosity is advised. Material and Methods: Tibial tuberosity transfer was performed in our center on 80 knees in 66 patients (40 females, 26 males) during the past 13 years (mean age 23 range 15 – 52). One surgeon supervised all the operations. The average follows-up was 6.2 years (one to thirteen years). All patients were examined clinically for the purpose of this study. The Lisholm and Karlsson scoring system were used to evaluate the results. Radiographs of both knees were also taken. Fifteen knees had no dislocation of the patella prior to the operation, seventeen knees had 1 to 10 eleven knees had 10 to 50, ten knees 50 to 100, and twenty-seven knees had more than hundred dislocations of the patella prior to surgery. Ten of these knees had daily dislocations of the patella. All operations were done either by selective epidural anesthesia (only sensory and not motor) or general anesthesia without muscle relaxant using quadriceps muscle stimulation. The mean tibial tuberosity medialisation, anteriorisation and distalisation was 1.4 cm (0–2.5 cm) 0.4cm (0–1.1cm) and 0.87cm (0–1.2cm) respectively. Results: When interviewed by an independent examiner 87% of the patients reported improvement and only 4.3% (3 patients) reported worsening of their condition after the operation. 84% of the patients stated they would have the operation again. All patients had full active range of motion on both knees without extension lag. At the final evaluation visit the Lisholm and Karlsson scores were good and excellent in 72% and 72.5%, 18.8% and 23.5% had fair results and only 8.7% and 4.4% had poor results respectively. The poor results correlated well with the degree of the patella cartilage damage found during surgery, poor selection of patients and extreme ligamentous laxity. There were two complications: one non-union of the tibial tuberosity treated successfully with bone grafting and one non displaced fracture bellow the osteotomy, treated conservatively. Both had excellent results. Conclusion: We conclude that distal patella re-alignment done by tibial tuberosity transfer is a reliable technique for the treatment of patello femoral pain secondary to mal-alignment

INTRODUCTION – Tuberosity fractures of the calcaneum are rare injuries. The traditional operative treatment involves open reduction and internal fixation with a tension band wire construct. We have developed a new technique of fixing these fractures with internal fixation using cannulated screws and a figure of eight wire. This paper describes the new technique outlining its advantages and compares the 2 methods of fixation biomechanically to determine their properties with respect to fracture fixation. METHOD – 20 sections of bovine bone were taken to act as an experimental model for the calcaneum. They were osteotomised to create the posterior process fracture model. 10 were fixed using a traditional tension band wire construct and 10 were fixed using the cannulated screw and wire construct. Each construct was subjected to biomechanical testing to identify the stiffness, energy to failure and load to failure. RESULTS – During loading the cannulated screw and wire constructs showed a significant increase in stiffness and energy to failure compared to the tension band wire constructs. CONCLUSION – The increased stability of the cannulated screw construct demonstrated by the testing offers biomechanical benefit over the traditional tension band wire construct. This, as well as the improved technical aspects of the cannulated screw fixation, may be beneficial for clinical use

Tuberosity ‘avulsion’ fractures to the base of the fifth metatarsal respond well to symptomatic treatment. The purpose of this study was a prospective comparison of clinical and radiological outcome with treatment in a plaster slipper, compared to a tubigrip support. Ethical approval was obtained and written consent with an information sheet issued at the first fracture clinic appointment. Forty three patients with this fracture were allocated to one of our two treatment groups and followed up at regular intervals over a 12 week period or until they were suitable for discharge. A combined foot score (maximum 100 points) was used at each follow up appointment to measure levels of pain (40 points) and function (60 points). A check radiograph was taken prior to discharge to assess union. A repeated measures analysis was used to assess any difference between the two treatment groups and whether this changed with time. Results indicated no overall significant difference between the two treatment groups with a mean foot score of 73.5 for the tubigrip group and 80.3 for the plaster slipper group over the entire treatment period. At 2 weeks post injury the plaster group (70.9) had a significantly (p< 0.01) better combined foot score at assessment in comparison to the tubigrip group (54.1).By the 5–8 week stage, the mean combined foot scores had improved and were comparable at 89.5 (tubigrip) and 90 (plaster slipper). Radiographs taken prior to discharge indicated two patients in each treatment group with significant fracture site displacement. One patient remained clinically symptomatic and underwent surgical fixation. In this small cohort of patients the eventual clinical and radiological outcomes were comparable. During the initial 2 week treatment phase the plaster slipper group recorded a significantly better mean foot score

Purpose: The three dimensional position of the tuberosity and the tension of the rotator cuff influence the structural changes of the rotator cuff and their influence on clinical results of reversed trauma prostheses. We propose this technique with it of a biological support, the fractured humeral head, adequately modeled, in order to give again the just tension to the cuff. Method: from February 2007 and February 2009 we treated 29 patients with a reversed trauma prostehes, in 7 cases we have practiced the bony necktie, for giving a support to the correct reconstruction of the tuberosity. The patients have an average of 71,5 years and was evaluated with Constant score and radiographic study with mean follow-up of 18,6 months. Results: Improvement of postoperative Constant score and radiographic good results were correlated with satisfactory subjective results. However, these results will have to be confirmed with more cases and later revision. Conclusion: Tuberosity position and healing is critical for clinical and radiographic outcome in shoulder arthroplasty in trauma. In particular the rate resorption of the tuberosity in Reverse Trauma Prostheses still is elevated. we propose a new surgical technical in order to give again the just position to the tuberosity fractured and therefore to give tension to the rotator cuff

A fracture of the tuberosity is associated with 16% of anterior glenohumeral dislocations. Manipulation of these injuries in the emergency department is safe with less than 1% risk of fracture propagation. However, there is a risk of associated neurological injury, recurrent instability and displacement of the greater tuberosity fragment. The risks and outcomes of these complications have not previously been reported. The purpose of this study was to establish the incidence and outcome of complications associated with this pattern of injury.

We reviewed 339 consecutive glenohumeral dislocations with associated greater tuberosity fractures from a prospective trauma database. Documentation and radiographs were studied and the incidence of neurovascular compromise, greater tuberosity fragment migration and intervention and recurrent instability recorded.

The mean age was 61 years (range, 18–96) with a female preponderance (140:199 male:female). At presentation 24% (n=78) patients had a nerve injury, with axillary nerve being most common (n=43, 55%). Of those patients with nerve injuries 15 (19%) did not resolve. Greater tuberosity displacement >5mm was observed in 36% (n=123) of patients with 40 undergoing acute surgery, the remainder did not due to comorbidities or patient choice. Persistent displacement after reduction accounted for 60 cases, later displacement within 6 weeks occurred in 63 patients. Recurrent instability occurred in 4 (1%) patients. Patient reported outcomes were poor with average EQ5D being 0.73, QDASH score of 16 and Oxford Shoulder Score of 41.

Anterior glenohumeral dislocation with associated greater tuberosity fracture is common with poor long term patient reported outcomes. Our results demonstrate there is a high rate of neurological deficits at presentation with the majority resolving spontaneously. Recurrent instability is rare. Late tuberosity fragment displacement occurs in 18% of patients and regular follow-up for 6 weeks is recommended to detect this.

Aims

The outcomes following nonoperative management of minimally displaced greater tuberosity (GT) fractures, and the factors which influence patient experience, remain poorly defined. We assessed the early patient-derived outcomes following these injuries and examined the effect of a range of demographic- and injury-related variables on these outcomes.

Shoulder arthroplasty procedures continue to increase in prevalence and controversy still remains about the optimal method to manage the subscapularis. Scalise et al. performed an analysis of 20 osteotomies and 15 tenotomy procedures, and found the tenotomy group had a higher rate of abnormal subscapularis tendons on ultrasound examination. There was one tendon rupture in the subscapularis tenotomy group and no ruptures in the osteotomy group. Jandhyala et al. retrospectively examined 26 lesser tuberosity osteotomies and 10 subscapularis tenotomies for arthroplasty, and their study demonstrated a significant improvement in the belly press test for the osteotomy group. Lapner et al. performed a randomised controlled trial assigning patients to either a lesser tuberosity osteotomy or a subscapularis peel procedure. They evaluated 36 osteotomies and 37 subscapularis peels. The outcomes evaluated were Dynamometer internal rotation strength, the Western Ontario Osteoarthritis of the Shoulder Index (WOOS) score and American Shoulder and Elbow Surgeons (ASES) score, and in a subsequent paper they evaluated the healing rates and Goutallier grade. Their studies illustrated no difference in the internal rotation strength between groups. Both groups significantly improved WOOS and ASES scores postoperatively, but the difference was not significant between groups. Goutallier grade increased significantly in both groups, but there was no significant difference between the groups. Overall, the different approaches have not demonstrated a meaningful clinical difference. Further studies are needed to help understand issues leading to subscapularis complications after arthroplasty.

Glenohumeral dislocation is complicated with a greater tuberosity fracture in 16% of cases. Debate regarding the safety of closed reduction in the emergency department exists, with concerns over fracture propagation during the reduction manoeuvre. The study aim was to report the results of closed reduction, identify complications and define outcome for these injuries.

188 consecutive glenohumeral dislocations with a tuberosity fracture were identified from a prospective database from 2014–2017. 182 had an attempted closed reduction under appropriate sedation using standard techniques, five were manipulated in theatre due to contra-indications to sedation. Clinical, radiographic and patient reported outcomes, in the form of the QuickDASH and Oxford Shoulder Score (OSS), were collected.

A closed reduction in the emergency department was successful in 162 (86%) patients. Two iatrogenic fractures of the proximal humerus occurred, one in the emergency department and one in theatre, representing a 1% risk. 35 (19%) of patients presented with a nerve lesion due to dislocation. Surgery was performed in 19 (10%) cases for persistent or early displacement (< 2 weeks) of the greater tuberosity fragment. Surgery resulted in QuickDASH and OSS scores comparable to those patients in whom the tuberosity healed spontaneously in an anatomical position (p=0.13). 18 patients developed adhesive capsulitis (10%).

Glenohumeral dislocation with greater tuberosity fracture can be safely treated by closed reduction within the emergency department with a low risk of humeral neck fracture. Persistent or early displacement of the tuberosity fragment will occur in 10% of cases and is an indication for surgery.

Distal femoral physeal fractures can cause of growth distrurbance which frequently requires further surgical intervention. The aim of this study was to determine if tibial tuberosity ossification at the time of injury can predict further surgery in patients who have sustained a physeal fracture of the distal femur.

We retrospectively investigated all patients who had operative treatment for a distal femoral physeal fracture at a paediatric level one trauma center over a 17 year period. Logistic regression analysis was performed investigating associations between the need for further surgery to treat growth disturbance and tibial tuberosity ossification, age, Salter Harris grade, mode of fixation or mechanism of injury.

74 patients met the inclusion criteria. There were 57 boys (77%) and 17 girls (23%). The average age at time of injury was 13.1 years (range 2.-17.1 years). Following fixation, 30 patients (41%) underwent further surgery to treat growth disturbance. Absence of tibial tuberosity fusion to the metaphysis was significantly associated with need for further surgery (p = < 0 .001). Odds of requiring secondary surgery after tibial tuberosity fusion to metaphysis posteriorly (compared with not fused) were 0.12, 95% CI (0.04, 0.34). The estimate of effect of tibial tuberosity ossification on reoperation rates did not vary when adjusted for gender, mechanism, fixation and Salter Harris grade. When accounting for age, the odds of further operation if the tibial tuberosity is fused to the metaphysis posteriorly (compared with not fused) were 0.28, 95% CI (0.08, 0.94).

Tibial tuberosity ossification stage at time of injury is a predictor of further surgery to treat growth disturbance in paediatric distal femoral fractures. Children with distal femoral physeal fractures whose tibial tuberosity was not fused to the metaphysis posteriorly were 8.3 times more likely to require further surgery.

Subscapularis tenotomy (SST) has been the preferred approach for shoulder arthroplasty for decades but recent controversy has propelled lesser tuberosity osteotomy (LTO) as a potential alternative. Early work by Gerber suggested improved healing and better outcomes with LTO although subscapularis muscular atrophy occurred in this group as well with unknown long-term implications. However, we previously performed a biomechanical study showing that some of the poor results following tenotomy may have been due to historic non-anatomic repair techniques. Surgical technique is critical to allow anatomic healing – this is true of both SST or LTO techniques. A recent meta-analysis of biomechanical cadaveric studies showed that LTO was stronger to SST at “time-zero” with respect to load to failure but there were no significant differences in cyclic displacement.

A recent study evaluated neurodiagnostic, functional, and radiographic outcomes in 30 patients with shoulder arthroplasty who had SST. The authors found that the EMG findings were normal in 15 patients but abnormal in the other 15 and that these abnormalities occurred in 5 muscle groups (not just the subscapularis). In another study, patient outcomes were inferior in those patients who had documented subscapularis dysfunction following SST compared to patients who had LTO (none of whom had subscap dysfunction). The literature is not clear, however, on ultimate outcomes based on subscapularis dysfunction post-arthroplasty with some studies showing no difference and others showing significant differences.

We performed an advancement and medial transfer of the tibial tuberosity based on Fulkerson's principle to treat intractable anterior knee pain associated with patellofemoral maltracking diagnosed by dynamic MRI.

Between January 1998 and July 2000 twenty-two patients had 28 knees operated for anterior knee pain. There were 4 men and 18 women with a mean age of 28 years (range 18-41). Indications for surgery were [a] failure to improve after six months of physiotherapy and [b] patellofemoral maltracking evident in dynamic MRI. Mean follow-up was for 37 months (23 – 42). Knee instability score modified by Fulkerson was employed for objective and subjective assessment.

Objectively 22 (79%) knees achieved good to excellent results. Four knees (14%) had fair, and two (7%) had poor results. Excellent and very good results were seen in 20 knees. These patients were a younger age group (mean age 21 years) and had minimal degeneration (grade I-II) of the patellofemoral joints. Two patients achieved good results. One of them had moderate (grade III) and one minimal (II) arthritis. Three knees with fair results had advanced (grade IV or V) and one had moderate (grade III) arthritis. Out of two patients who had a poor result, one had advanced degeneration (grade V) that later required a patellofemoral joint resurfacing. The other was a 24 year old woman with grade II changes. She was treated by the pain therapy team.

Anterior displacement of the tuberosity in the presented study was kept to 5 mm to avoid the possible complications of wound break down. The overall length and depth of the osteotomy was also reduced to minimise risk of fracture and commence early mobilisation.

Based on our results there is a strong case of justification for Anteromedialisation of tibial tuberosity using a smaller length of osteotomy and lesser degree of anteriorisation in carefully selected patients with Patellofemoral arthralgia associated with maltracking patella.

Previous studies describing drill trajectory for single incision distal biceps tendon repair suggest aiming ulnar and distal (Lo et al). This suggests that the starting point of the drill would be anterior and radial to the anatomic insertion of the distal biceps tendon. Restoration of the anatomic footprint may be important for restoration of normal strength, especially as full supination is approached.

To determine the safest drill trajectory for preventing injury to the posterior interosseous nerve (PIN) when repairing the distal biceps tendon to the ANATOMIC footprint through a single-incision anterior approach utilising cortical button fixation.

Through an anterior approach in ten cadaveric specimens, three drill holes were made in the radial tuberosity from the centre of the anatomic footprint with the forearm fully supinated. Holes were made in a 30º distal, transverse and 30º proximal direction. Each hole was made by angling the trajectory from an anterior to posterior and ulnar to radial direction leaving adequate bone on the ulnar side to accommodate an eight-millimetre tunnel. Proximity of each drill trajectory to the PIN was determined by making a second incision on the dorsum of the proximal forearm. A K-wire was passed through each hole and the distance between the PIN and K-wire measured for each trajectory.

The PIN was closest to the trajectory K-wires drilled 30° distally (mean distance 5.4 mm), contacting the K-wire in three cases. The transverse drill trajectory resulted in contact with the PIN in one case (mean distance 7.6 mm). The proximal drill trajectory appeared safest with no PIN contact (mean distance 13.3 mm). This was statistically significant with a Friedman statistic of 15.05 (p value of 0.00054).

When drilling from the anatomic footprint of the distal biceps tendon the PIN is furthest from a drill trajectory aimed proximally. The drill is aimed radially to minimise blowing out the ulnar cortex of the radius.

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Introduction

Tibial tuberosity and trochlear groove (TT-TG) distance has been investigated for the patients with primary patellofemoral subluxation/dislocation. To date, TT-TG distance after TKA has not been evaluated, and the effect of postoperative TT-TG distance on patellar tracking is unknown. The purpose of the current study was to investigate the effect of TT-TG distance and rotational position of the femoral and tibial components on patellar tilt after TKA.

Aims

Isolated greater tuberosity fractures make up 17–21% of proximal humeral fractures, 30% are associated with shoulder dislocation. Conservative management of minimally displaced fractures (<5 mm) is recommended. There are few guides to which and how many fractures displace over time.

The aim of the study was to assess the rate of greater tuberosity non union in reverse shoulder arthroplasty performed for proximal humerus fractures and to assess if union is related to type of fracture or the intraoperative reduction of the greater tuberosity.

All cases of reverse shoulder arthroplasty for proximal humerus fractures at our institution over a three year period were retrospectively reviewed from casenotes and radiologically and the position of the greater tuberosity was documented at immediate post op, 6 months and 12 months. Any malunion or non union were noted.

A total of 27 cases of reverse shoulder arthroplasty for proximal humeral fractures were identified. 4 cases did not have complete follow up xrays and were excluded from analysis. The average age at operation of the cohort of the 23 remaining patients was 79 years (range 70–91). The greater tuberosity was anatomically well positioned intraoperatively in 17 of the 23 cases.

At the end of 12 months there were 4 cases of tuberosity non union (17%), all except one occurring in poorly intraoperatively positioned greater tuberosity. 50% (3 out of 6) of greater tuberosities displaced further and remained ununited if the intraoperative position was poor. Only 6% (1 out of 17) greater tuberosities did not unite if the greater tuberosities was reduced anatomically. Intra operatively position of the greater tuberosity was strongly associated with their union (Fischer's exact test p<0.05). Union of greater tuberosity was not statistically associated with fracture pattern (Fischer's exact test p=0.48).

Our case series show a low rate of tuberosity malunion after reverse shoulder arthroplasty for proximal humerus fracture. Good positioning and fixation of the greater tuberosity intra operatively is a strong predictor of their uneventful union to shaft.

Proximal fifth metatarsal fractures distal to the tuberosity, also known as Jones’ fractures, are troublesome fractures to manage with a high incidence of delayed union and nonunion.

We conducted a retrospective study of 32 patients with fractures of the fifth metatarsal distal to the tuberosity over a three year period. The aim was to assess healing with non-weight bearing and variations of weight bearing mobilization including minimal, partial and full weight bearing. This is one of the largest reported series of such fractures. These fractures were classified as acute fractures (14 fractures), fractures with features of delayed union (15 fractures) and fractures with features of nonunion (three fractures) at presentation according to the radiological classification used by Torg in 1984. These patients were treated in a plaster cast and mobilised either non-weight bearing or with variations of weight bearing. These patients were followed up for a mean of 16 months.

Our findings correspond with those observed by Torg and we describe a correlation between the radiological appearance of the fracture at presentation and the clinical course. Prevailing guidelines for the management of these fractures are ambiguous. A standardized classification is important because there is great variability in the types of fractures and appropriate treatment. It is important that radiological features are correlated with clinical features and appropriate treatment instituted. The treatment of choice for acute fractures is immobilization of the limb in a below-knee non-weight bearing plaster for 6 to 8 weeks. Fractures with delayed union may eventually heal if treated non-operatively, although this may take up to 20 weeks. An active athlete will benefit from early surgery. Fractures with symptomatic nonunion require surgery.

Purpose: To present the results of the tibial tuberosity osteotomy as part of the surgical approach for total knee replacement. Material and Methods: Tibial tuberosity osteotomy was performed during TKR for better exposure in 19 knees corresponding to 19m patients (9 male, 10 female), with average age 76 years (68–80). Four of the procedures were revisions. Fifteen were primary TKR, ten of which had been subjected to high tibial osteotomy previously. The rest þve patients had excessive valgus deformity (over 20 degrees), and they were approached through a lateral parapatelar incision. In two cases screws only were used to stabilize the osteotomised tubercle, and wire loops in the rest of them. Patients were instructed for partial weight bearing for six weeks postoperatively. Results: All osteotomies united in less than four months. In three cases (including the two with only screw þxation), proximal migration of the tuberosity was noted, but less than 2cm. No skin problems were encountered. Three patients,(22%), complained for anterior knee pain. Preoperative mean range of movement was 75 degrees, and improved to 90 degrees postoperatively. Average blood loss was 850 cc. Conclusions: The tibial tuberosity osteotomy offers excellent exposure in the revision and difþcult primary TKR, but it lengthens the operative time, and the blood loss is higher.

Purpose: Consolidation of the tuberosity is the key to success of shoulder arthroplasty for fracture. The purpose of this study was to assess the number and causes of tuberosity complications in order to find solutions for this problem.

Material and methods: This retrospective multicentric study included 334 shoulder prostheses implanted for fracture between 1991 and 2000. Two different prostheses were used: 300 standard Aequalis prostheses implanted between 1991 and 1997 (mean follow-up four years) and 31 Aequalis Fracture prosthesis between 1999 and 2000 (mean follow-up nine months). Radiological results were assessed on the postoperative and last follow-up x-rays. The Constant score was used for clinical assessment.

Results: For the 300 standard prostheses, the Constant score was 54 points with active anterior elevation = 104°. For the 31 fracture prostheses, the Constant score was 58 points with active anterior elevation = 114°. According to the operator’s assessment, 49% of the postoperative radiological results were fair or poor and objectively 35% of the tuberosities were poorly positioned with the standard prosthesis and 22% with the fracture prosthesis. Twenty-six percent of the good or poorly positioned tuberosities migrated secondarily with the standard prosthesis and 10% with the fracture prosthesis. Statistically significant prognostic factors limiting tuberosity complications were: satisfactory initial osteosynthesis with correct prosthesis height and retroversion facilitated by use of the fracture system, rehabilitation in a specialised centre, relative immobilisation during the first postoperative month limiting exercises to balancing movements which divided the number of secondary migrations by two compared with immediate moblisation (14% versus 27%).

Discussion: A precise analysis of the radiograms revealed a very high rate of tuberosity complications (50%). There has been little study of these complications which are underestimated in the literature. The Aequalis fracture prosthesis can reduce these tuberosity complications two-fold. Postoperative immobilisation also reduces two-fold tuberosity migrations. These observations are against the early passive motion advocated by Neer. Finally, the quality of tuberosity fixation is crucial for success. The surgeon must concentrate on this element, searching to achieve a perfectly positioned prosthesis on the peroperative x-ray.

The aim of our biomechanical study was to find out whether the prosthetic design, especially of the metaphyseal part, and the type of tuberosity fixation influences the primary stability in shoulder arthroplasty.

Materials and Methods: 16 fresh frozen human cadaveric humeri were dissected until only the rotator cuff remained. A four-part fracture was simulated by osteotomy. In a first step two types of shoulder prosthesis (open stem versus closed stem) were used. The Tornier Aequalis prosthesis (open stem) using suture fixation and the Mathys Affinis fracture prosthesis (closed stem) using cable fixation were implanted according to standard techniques. The specimens were then loaded into a servo-pneumatic testing device in 25° of abduction. In 20 consecutive cycles traction of 40 Newton was alternating exerted on the subscapularis and infraspinatus tendon, while a continuous force of 40 Newton was exerted on the greater tuberosity to simulate the pull of the m. supraspinatus. The motion of the fragments was recorded by 2 high speed cameras. The following parameters were investigated : Failure of osteosynthesis, intertuberosity motion, motion lesser tuberosity-shaft, motion greater tuberosity-shaft, motion metaphysis-shaft. After completing the first series the cable fixation exposed to be more stable. In a second series we compared cable versus suture fixation in the Affinis fracture prosthesis to find out whether the stability was depending on the prosthesis design.

Results:

Series 1: The intertuberosity motion was significantly lower in the cable prosthesis. The tuberosity-shaft motion was significantly lower in the cable group for greater and lesser tuberosity. The metaphysis - shaft motion did not significantly differ in both groups.

Conclusion: Highest primary stability of tuberosity fixation in trauma-arthroplasty of the shoulder was measured in cable fixation and closed stem. We proved that the kind of fixation was the most important factor determing the stability. Metaphyseal design was less important.