Aims

We report the natural course of Baker’s cysts following total knee arthroplasty (TKA) at short- and mid-term follow-up.

The giant cell tumor of bone (GCT) is a locally aggressive intraosseous neoplasm, with an uncertain biological behavior, constituted of giant multinuclear cells spread over tumoral tissue with a nucleus presenting the same features of the ovoid and fusiform cells forming its stroma. The local recurrence of GCT is often observed, mainly in the first three years after treatment, giving a rate of recurrence ranging in 20 to 50% of cases. Further aggravating the recurrence is the fact that after the relapse, the patient often also presents metastases in other organs.

The aim of this study was to identify and to characterize differentially expressed genes that can be used in the prognostic, treatment and understanding of this physiopathology. To identify novel genes differentially expressed in GCT, we have applied rapid subtractive hybridization (RaSH). Samples of GCT and normal tissues were obtained at Tumor Bank of Barretos Cancer Hospital. After RNA extraction and cDNA synthesis the samples were submitted to Rapid hybridization Subtraction (RaSH) methodology for subtractive libraries elaboration.

The RaSH subtractive libraries reveals the presence of 619 different clones including both normal and tumor tissues were identified. Of these, 450 in tumor sample and 169 in control tissue. Four biomarkers candidates were selected for validation: ZAK, KTN1, NEB, and ROCK1 genes, whose functions are, related to cell cycle checkpoint, transport of organelles, cytoskeletal matrix and cell adhesions. The validation of selected differentially expressed genes was performed using real time PCR. The putative molecular markers found in this work may help to find the basis for a molecular comprehension of GCT, thus improving diagnosis, treatment and outcome for patients with this tumor.

Gorham syndrome is a rare disease of unknown cause. It is characterized by the massive bone destruction associated to bone angiomatosis. It was first described by Jackson in 1838. Gorham and Stout published their initial report in the fifth decade of the last century. The diagnosis depends on the exclusion of other diseases that cause bone lysis. The treatment has no uniformity between the oncologists, and different modalities of therapeutic procedures are being used as radiotherapy, biphosphonates, interferon and surgery.

This case reports a man, 44 years old, caucasian farmer that had a progressive pain in the left groin one year ago. The pain was getting worst and migrated to the left hip. A pelvis X-ray revealed isquiatic lysis with total disappearing of the bone. The left hip presented diffuse lytic areas too. The clinical profile of the patient was good and it was discrepant when compared to the X-rays with bone destruction.The investigation was done with bone scintilography, MRI of the pelvis, computed tomography (CT) of abdomen and chest, blood analysis of PTH, calcium, phosphate, eletrophoresis of proteins, PCR, hepatic function, and two consecutive bone biopsies of the left hip and pelvis. All exams excluded metastatic or primary bone tumors. A multi-disciplinary team of clinical oncologists, endocrinologists, nephrologists excluded other neoplastic, metabolic and rare diseases as Hadju and Cheney acro-osteolysis, carpal and tarsal osteolysis, multicentric osteolysis with nephropaty, hereditary multicentric osteolysis, Joseph acro-osteolysis, Shinz acro-osteolysis, Faber disease and Winchester disease. A multidisciplinary meeting decided by the orthopaedic surgery and radiotherapy to relieve the pain and to achieve the pathological diagnosis. The girdlestone surgery was done and the histopathological analysis showed diffuse angiomatosis in the specimen, diagnosing Gorham syndrome.

Gorham syndrome diagnosis depends on a tripod: clinical exclusion of other pathologys, image investigation and histopathology diagnosis. All three characteristics are primordial to the diagnosis of this pathology and a full investigation in a multidisciplinary level is necessary.

Subject: The dislocation of the graft and fixation material within the femoral tunnel is a concern in ACL-reconstruction but is not directly accessible to biomechanical investigation. The current study was carried out to address particularly the intra-tunnel-movement of the graft under repetitive load.

Material and methods: Three graft/fixation combinations were biomechanically investigated: a human BPTB-Graft fixed with a 7x23mm interference screw and a double tendon loop (porcine foot extensor) fixed with either a TransFix post or a continuous loop Endobutton. The grafts and the fixation material were fitted with multiple tantalum markers (0.5 mm). Then the grafts were anchored in human femora according to clinical standards. A servo-hydraulic materials testing machine was used to repetitively load the test specimen with a force between 50 and 250 N (max. 1000 cycles). Each fixation type was tested seven times. After definite intervals the position of the markers was recorded using fluoroscopy. The dislocation of the grafts was determined from the recorded images using appropriate software. Standard geometry could be employed due to the uni-dimensional nature of the intra-tunnel movement.

Results: Premature failure occurred neither with BTB-grafts nor with TransFix anchored tendon loops but was observed with the Endobutton fixation, where the Endobutton was pulled through the lateral cortex in two cases. The dislocation of the grafts after 200 and 500 cycles was significantly higher with the Endobutton fixation (1.3±0.9 and 1.9±1.2 mm resp.). In the TransFix group the dislocation was 0.14±0.10 and 0.40±0.27 mm, which was not statistically different from the BTB group with 0.13±0.13 mm and 0.24±0.16 mm respectively.

Conclusions: The stability of TransFix anchored tendon loops under repetitive submaximal loads reaches that of BPTB grafts fixed with interference screws. In the model employed here the extra-cortical fixation showed less resistance against dislocation.

Clinical relevance: The current results can aid the surgeon in the choice of the graft/fixation combination. Factors other than the biomechanical stability have to be considered, particularly the ingrowth behavior of different grafts and fixation types.

Our aim was to investigate vascular endothelial growth factor (VEGF) expression after lacerations of a meniscus in a rabbit model. Specimens of meniscus were examined using immunohistochemistry, enzyme-linked immunoassay and the reverse transcription polymerase chain reaction after one, two, five or ten weeks. In the periphery of the meniscus 90% of the lacerations had healed after five and ten weeks, but no healing was observed in the avascular area. Expression of VEGF protein and VEGF mRNA was found in the meniscus of both the operated and the contralateral sites but both were absent in control rabbits which had not undergone operation. The highest expression of VEGF was found in the avascular area after one week (p < 0.001). It then lessened at both the vascular and avascular areas, but still remained greater in comparison with the control meniscus (p < 0.05). Despite greater expression of VEGF, angiogenesis failed at the inner portion. These findings demonstrated the poor healing response in the avascular area which may not be caused by an intrinsic cellular insufficiency to stimulate angiogenesis.

Aims: To clarify whether joint loading after meniscus repair causes increased pressure on the femoral condyle and is responsible for early cartilage damage. Methods: In sixteen human cadaver knees a bucket handle tear was created at the posterior horn of the medial and lateral meniscus. The lesion was repaired using two biodegradable implants (either Stingerª, Arrow¨, Dartª or Meniscal Screwª) on each occasion. Loading was compared to intact menisci and menisci after suture repair using 2/0 Ethibond. The specimens were mounted into specially designed jigs, taking all degree of freedom of the knee joint into account, and þxed to a material testing machine (Bionix 858 MTS). Constant loading of 350 N was performed during knee motion of 0¡Ð90¡ of ßexion. The meniscofemoral pressure was measured using the Tekscansystem. All þxation techniques were tested þve times. Results: Increased joint loading at the posterior horn occurred with increased ßexion angle of 0¡, 30¡, 60¡ and 90¡ of knee ßexion in the medial and lateral compartment (p< 0.05). No signiþcant increase in joint loading was noticed after meniscus repair with biodegradable implants. Conclusions: Biodegradable implants do not cause higher meniscofemoral joint loading due to meniscus implants in the posterior horn and resulting cartilage damage at the femoral condyle is unlikely.

One of the advantage in using unicondylar prosthesis seems to be the preservation of the bone stock, which allows most often easily revision to a total knee replacement if required. The purpose of the study was to compare the patients outcome after revision of unicondylar prosthesis with a group of patients who have received total knee replacement primarily.

Material and Method: 28 patients after revision unicondylar prosthesis (group A) and 28 patients after primary total knee replacement (group B) were included in the study. The two groups were matched according to age, sex, weight, height, type of prosthesis and follow-up time. The patients’ evaluation was based on the Knee-Society-Score and the WOMAC-score. X-rays of the knee were taken in the AP weight bearing and lateral view.

Results: In group A the average follow-up time was 55±15 months and in group B 56±13 months. The knee-score showed 71.8±18 and 80.4±10.4 points and the function-score 56.1±15 and 62±19 points for group A and group B respectively without any statistical difference. The subjective assessment according to the WOMAC score showed difference in the functional outcome. A better range of motion of 110±11° was noticed for group B in comparison with group A 102±8° (p=0.004). The revised patients required a significantly higher poly-ethylene-inlay (12.9±3mm) compared to the primarily implanted ones (10.3±3mm) (p=0.004).

Discussion: Based on our findings revision of unicondylar to total knee replacement provides comparable results to primarily implanted total knee arthroplasty and should be considered for the treatment of unicompartmetal osteoarthritis even in younger patients, where a revision operation during lifetime is more likely. Despite the difference regarding the height of the inlay of 3mm, adequate bone stock was still found in order to implant an unconstraint type of knee prosthesis. The impaired functional outcome seems to be related to the fact of the reoperation and a significant longer history of osteoarthritis for group A in comparison with group B.

The loss of full muscle activation contributes to weakness of the quadriceps muscle in patients with deficiency of the anterior cruciate ligament (ACL). We examined whether a deficit of voluntary activation (VA) of the quadriceps muscle can be reversed by reconstruction of the ACL and assessed its influence on muscle strength and clinical parameters.

We evaluated 12 male subjects with an isolated tear of the ACL and 12 matched control subjects before operation and two years after reconstruction of the ACL. Assessment included measurements of isometric knee-extension torque at maximal voluntary contraction (MVC force), knee stability tests, the International Knee Ligament Standard Evaluation Form and the Tegner activity score. A sensitive method of twitch interpolation was used to quantify the VA and to calculate true muscle force.

Before operation we found a deficit of VA on both the injured (mean ±SEM 74.9 ± 3.5%) and the uninjured side (74.6 ± 3.0%) in comparison with the control group (91 ± 0.9%). Two years after reconstruction of the ACL the VA improved significantly on both sides but remained less than that of the controls. Correlation analysis revealed an improvement of the VA in patients who returned to a higher level of activity. The deficit of true muscle force, however, persisted regardless of the clinical outcome and ligament stability.