HEAVY METAL SOUNDS GREAT! RESULTS WITH THE ARTICULAB PROSTHESIS

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1 HEAVY METAL SOUNDS GREAT! RESULTS WITH THE ARTICULAB PROSTHESIS F REUTHER OBJECTIVES A trauma shoulder prosthesis was developed in 1999 because fracture prostheses were rarely performed and a simple method was required [9]. At the Same time, after primary cementing of the Stern, the prosthesis needed to be height and retroversion adjustable to guarantee an optimal fit. The philosophy of design derived from the concept that a round central Part with spikes would improve primary stability. The inner shape of the proximal humerus (inner part of tuberosities) fits the round prosthesis shape so that a more stable refixation can be achieved than with a narrow or Square prosthesis design. These results are confirmed in studies by Frankle et al. [3], who in biomechanical tests examined the effect of an encircling suture in connection with an irredar surface with regard to primary stability. Fig. 1: Articu/a@ trauma shoulder endoprosthesis, exploded assembly view.

2 SHOULDER CONCEPTS PROXIMAL HUMERAL FRACTURES & FRACTURE SEQUELAE Fig. 2: CT analysis fracture prosthesis The data analysis of CTs for fractured and non-fractured proximal humeri formed the basis of developing the new central part of the prosthesis. In a biomechanical test Nijs et az. [7] compared tuberosity refixation in various prosthesis models. They found significantly higher stability for a voluminous central part with irregular surface and also for cable fixation of the tuberosities over suture fixation. METHODS In a multicentre study at 6 clinics in Germany, 237 cases were included [10]. From 2000 to 2003 shoulder prostheses were inserted for proximal humerus fractures which were assessed as being non reconstructable. In all cases the modular, height adjustable shoulder prosthesis ArticulaO (Mathys Ltd Bettlach, Switzerland) was used.

3 IfEAW METAI, SOIINDS GREAT! - RESULTS UVTH THE ARTICULAO PROSTHESIS Information for fracture types accor- importance of length of follow-up, proding to Neer [8], status of the tuberosi- portion of female patients and age and ties, surgical intervention and early gender adjusted CS. Comparative complications were collected. results were found in a large number of cases, a very high proportion of female The Constant Score (CS) and ASES Index patients and a long follow-up time as after 12 andior 24 months were evaluated. well as high average age. The healing of the tuberosities was examined by X-ray. A follow-up was possible for 153 patients. The missing patients Boileau Habermeyer r41 Reuther ['O] could not be reached for a vanety of rea- / 8 Centres 1 6 Cenfres 1 6 Centres sons (3 l), due to death (20) or poor gene- 1 ral health ( 13). Additionally telephone inquiries were carried out in 20 cases. RESULTS The X-ray analyses of the tuberosity status showed a significant correlation between gender (females have an increased risk of vanishing tuberosities, p< ) and age (P= 0.017). Osteoporosis also showed a correlation (p=0.04), though less significant. In the cases of vanished tuberosities, CS and ASES were significaatly lower, whereas CS in intact tuberosities was at 51.4 points, in vanished tuberosities at 39.9 points. Unexpectedly, the tuberosity healing did not correspond to the CS measured pain expenence (P= 0.7). There was a substantial correlation with the range of anteversion (p=0.0001) and abduction (P= ). OF CENTRE STUDIES Female: 68% All 3 studies pointed to the importance of correct positioning and tuberosity healing for good functional outcome. CONCLUSIONS The exact reconstmction of height and rotation is essential for good primary stability so that in a second step, i.e. osteointegration, secondary stability can be achieved [2, 51. We therefore decided to redesign the ArticulaB and introduced in May 2006 the AffinisO Fracture. In a prospective study over one hundred patients have been included. A comparison of existing multicentre studies on fracture prosthesis shows the

4 SHOULDER CONCEPTS PROXIMAL HUMERAL FRACTURES & FRACTURE SEQUELAE Fig. 3: Newly designed AffinisB Fracture, Central Part with bioactive coating (VPS+Bonit@), polished radius and holes. TECHNIQUE OF TUBERoSITy To achieve better fixation of the tuberosities two cross-holes were fitted to the central Part for insertion of non-resorbable sutures or cables. The altered central part was coated with Vacuum Plasma Spray (VPS) and Calciumphosphate-(CaP)-coating (BionitB). A biomechanical test was carried out on the refixation technique and standardised. After the sutures (red) are pulled through, the tuberosities are adjusted for height and fixed with retention stitches on the outer edge of the central part and over one another (green). Fig. 4: Insertion of sutures - Affinie Fracture refixation red: upper cross-hole - onset of supraspinatus tendon ("footprint") green: tuberosity fixation on the bone-tendon intersection blue: wiring of stem - supraspinatus and subscapularis tendons blue: closing of gap grey: cable - lower cross-hole - infraspinatus tendon posterior, subscapularis anterior

5 HEAW METAL SOUNDS GREAT! - RESULTS WITH THE ARTICULAO PROSTHESIS Subsequently for compression both tuberosities are fixed against the stem with wiring (blue) and finally a circular compression with cable (grey) or suture is made through the cross-hole of the central part. Crucial is stable osteosynthesis with anatomical positioning of the tuberosities. In a first clinical study Nijs et a16 found 83% of healed tuberosities which were refixed by cable on the new prosthesis design. CASE REPORT In a case report cable fixation and clinical results after one year are documented. FUTURE PROSPECTIVES When osteosynthesis is no longer feasible, intraoperatively it should be possible to choose the most suitable prosthesis. A trauma shoulder prosthesis with refixation of the tuberosities should always be aimed at when the rotator cuff is intact. When there is substantial disintegration of the proximal hurnerus andlor damage to the rotator cuff, a primary inverse prosthesis can be considered an option. Prosthesis Systems where there is a possibility of changing the process even after cementing of the stem leave both options Open. Decision criteria have not yet been evaluated sufficiently and will form the basis of future studies. Fig. 5: 3-part-fracture, female 70 y - AffinisB Fracture Follow-up

6 SHOULDER CONCEPTS PROXIMAL HUMERAL FRACTURES & FRACTURE SEQUELAE REFERENCES [I] BOILEAU P., TINSI L., LEHOUC J.C., MOLE D., SINNERTON R., WALCH. G Results of shoulder arthroplasty in acute Fractures of proximal humerus. In: Walch G, Boileau P (eds) Shoulder arthroplasty Spnngeu; Berlin, Heidelberg, New York. p [2] BOILEAU P., KRISHNAN S.G., TINSI L., WALCH G., COSTE J.S., MOLE D Tuberosity malposition and migration: reasons For poor outcomes aber herniarthroplasty For displaced fractures of the proximal humerus. J Shoulder Elbow Surg, 11 (5): p [3] FRANKLE M.A., ONDROVIC L.E., BLAINE A.M., LANCE H., WILLIAM E.L Stability of tuberosity reattachment in proximal humeral hemiarthroplasty. J Shoulder Elbo~v Surg. 417 Volunfe I I, Number 5, p [4] HABERMEYER P Univers-F~akturprothese 2. Symposium, Frakturpmthetikderproximalen Humerusfraktuu; Berlin. [5] MURACHOVSKY J., IKEMOTO R.Y., NASCIMENTO L.G., FUJIKI E.N., MILAN1 C., WARNER J.J Pectoralis major tendon reference (PMT): a new method for accurate restoration of hurneral lcngth ~vith hemiarthroplasty for fracture. J Shoulder Elbai~ Surg, 15(6): P [6] NIJS S., KUPPERS M., GOETHALS M., BROOS P Tuberosity healing in proximal humerus fracture arthroplasty: does fixaiion matter? Sn~rkolj, V Ljubljarza, Medimond. [7] NIJS S., MUELLER L.P., ROMMENS P., BROOS P Biomechanical comparison of tuberosity refixation in shoulder arthroplasty. 10" international Congress oj Shoulder and Elbo~i Surgery, Sept 16-20, Costa do Sauipe Bahia, Brasil. [8] NEER C.S., ROCKWOOD C.A Fractures and dislocations of the shoulder. In: Rockwood CA, Green DP, cditors. Fractures. 2'" ed. Philadelphia, J.B. Lippincott, 1984, P [9] REUTHER F., MUELLER S., WAHL D Management ol humeral head fractures with a trauma shoulder prosthesis: correlation between ioint Function and healing of the tuberosities. Acta 0rthop-~e2g. 73(2):p [10] REUTHER F Causes and consequences of the tuberosity healing in traurna shoulder prostheses. 10" International Congress o/' Shoulder and Elbow Surgery, Sept 16-20, Cost do Sauipe Bahia, Brasil.