Purpose: We carried out a biomechanical study by finite element analysis to compare treatment with a plate and treatment with a nail in pseudoarthrosis of the humeral shaft.

Materials and methods: We used a cadaver humerus and the two fixation devices to generate the geometry with design software (CATIA® v4.2). We then modelled the shapes with finite element analysis software (MSC.Patran®) and created three experimental models: healthy humerus, humerus with shaft pseudoarthrosis stabilised with AO plate and humerus with shaft pseudoarthrosis stabilised with locking nail. Both implants were titanium. The three models were subjected to nine different load conditions and the results compared.

Results: The nail model is stiffer than the plate in compression (3002.80 vs 789.68 N/mm), traction (6576.73 vs 1559.90 N/mm) and torsion (4.67 vs 2.73 N/mm). However, the plate model is biomechanically superior to the nail under other load conditions (mediolateral flexion, anteroposterior flexion, anteroposterior shear and mediolateral shear).

Conclusions: Although we can understand and compare the stability of the plate model with the nail, joint clinical and biomechanical studies are needed to determine the minimum stiffness required so that it will not interfere with the process of union under different load conditions.

Purpose: The purpose of this study is to investigate the external and internal vascular anatomy of the lunate bone. The genesis of lunatomalacia requires some combination of load, vascular risk and mechanical predisposition. The findings will be correlated with the major existing theories of the cause of lunatomalacia and the most frequent fractures associated with Kienbocks disease: transverse shear fracture and midcoronal fracture.

Material and methods: We studied 21 cadaver upper limbs using latex injection and Spalteholz technique. We investigated the extra- and intraosseous blood supply. In 17 wrists we evaluate the incidence and distribution of anatomic features, arthrosis, and soft tissue lesions.

Results: The lunate morphology was 5 Type I (29.4%), 11 Type II (64.7%) and 1 Type III (5.9%). The lunate was found to have a separate facet for the hamate in 47.1% (Size 3–6 mm). Most frequent arthrosis was identified in the radius (88.2%) and lunate (94.1%). The triangular fibrocartilage complex (TFCC) was found torn in 47%, the lunotriquetral interosseous ligament (LTIL) was torn in 23.5%, and the scapholunate interosseous ligament (SLIL) was torn in 53% of the wrists. Statistical analysis found a correlation between the presence of arthrosis at the proximal pole of the hamate and the presence of a lunate facet. There was also a correlation between the presence of a tear in the SLIL and the presence of cartilage erosion in the scaphoid (p= 0.002). Arthrosis on the lunate was found to have a correlation with an SLIL tear or TFCC tear. The nutrient vessels entered the lunate throught the dorsal and volar poles in all the specimens. Dorsal vessels enter the bone through one or two foramina in the proximal, ulnar, and nonarticular aspect of the bone. Two to six nutrient vessels were observed entering the volar pole throught a ligament insertion: radioscapholunate ligament of Testut-Kuentz, radio-lunate-triquetrum ligament and ulnar-lunate-triquetrum ligament.

Conclusions: The lunate had consistent dorsal and palmar arteries entering the bone in all the specimens. The supply blood and foramina number is more important in the volar pole of the lunate than the dorsal pole. The vascular patterns support a theory of compression fracture from repeated trauma, or anatomical predispositions as the most likely cause of Kienbocks disease.

Introduction and purpose: The results of hemiarthroplasty for the treatment of complex proximal humerus fractures are controversial since there are wide variations across series. In what follows, we shall present our experience and results with the implants we use, with a minimum follow-up of one year.

Materials and methods: 87 prostheses were revised (hemiartroplasty with cemented Neer II endoprosthesis) with a minimum follow-up of one year (1 to 10); 74 females and 13 males, 53 right and 34 left, with a mean age of 73.3 years (range: 51 – 82). Indications included three-part fractures (15 cases), four-part fractures (66) and fracture-dislocation (6). All patients were put on a postop customized standardized physical therapy program.

Results: The Constant test was performed after 3, 6 and 12 months postop, with a mean result of 44.57 points after 3 months, 49.52 after 6 months and 64.37 after 12 months. 90% of patients had either no pain or occasional pain and 85% of them subjectively described their condition as very good. Two patients were revised: one as a result of a lysis in his lesser tuberosity and the other because of a painful implant. There were two instances of a periprosthetic fracture and three infections (2 late ones and a post-fracture one).

Conclusions: Although these results might seem poor, it should be emphasized that heimarthroplasty led to a predictable absence of pain and to a perception by the patient that the result obtained was very good. Even if it is true that certain limitations were observed in terms of function and strength, patients were able to perform many of their daily life activities and gain a substantial degree of independence, albeit with certain restrictions. For this reason we consider the technique described as the procedure of choice for these types of fractures.