Hip Osteoarthritis (HOA) is the most common joint disorder and a major cause of disability in the adult population, leading to total hip replacement (THR). Recently, evidence has mounted for a prominent etiologic role of femoroacetabular impingement (FAI) in the development of early OA in the non-dysplastic hip. FAI is a pathological mechanical process, caused by abnormalities of the acetabulum and/or femur leading to damage the soft tissue structures. FAI can determine chondro-labral damage and groin pain in young adults and can accelerate HOA progression in middle-aged adults.

The aim of the study was to determine if the presence of calcium crystal in synovial fluid (SF) at the time of FAI surgery affects the clinical outcomes to be used as diagnostic and predictive biomarker.

49 patients with FAI undergoing arthroscopy were enrolled after providing informed consent; 37 SFs were collected by arthrocentesis at the time of surgery and 35 analyzed (66% males), median age 35 years with standard deviation (SD) 9.7 and body mass index (BMI) 23.4 kg/m²; e SD 3.

At the time of surgery, chondral pathology using the Outerbridge score, labral pathology and macroscopic synovial pathology based on direct arthroscopic visualization were evaluated. Physical examination and clinical assessment using the Hip disability & Osteoarthritis Outcome Score (HOOS) were performed at the time of surgery and at 6 months of follow up. As positive controls of OA signs, SF samples were also collected from cohort of 15 patients with HOA undergoing THR and 12 were analysed.

45% FAI patients showed CAM deformity; 88% presented labral lesion or instability and 68% radiographic labral calcification. 4 patients out of 35 showed moderate radiographic signs of OA (Kellegren-Lawrence score = 3). Pre-operative HOOS median value was 61.3% (68.10-40.03) with interquartile range (IQR) of 75-25% and post-operative HOOS median value 90% with IQR 93.8-80.60. In both FAI and OA patients the calcium crystal level in SFs negatively correlated with glycosaminoglycan (component of the extracellular matrix) released, which is a marker of cartilage damage (Spearman rho=-0.601, p<0.001).

In FAI patients a worst articular function after surgery, measured with the HOOS questionnaire, was associated with both acetabular and femoral chondropathy and degenerative labral lesion. Moreover, radiographic labral calcification was also significantly associated with pain, worst articular function and labral lesion. Calcium crystal level in SFs was associated with labral lesions and OA signs.

We concluded that the levels of calcium crystals in FAI patients are correlated with joint damage, OA signs and worst post-operative outcome. The presence of calcium crystals in SF of FAI patients might be a potential new biomarker that might help clinicians to make an early diagnosis, evaluate disease progression and monitor treatment response.

Introduction

Revision total hip arthroplasty is often associated with acetabular bone defects. In most cases, assessment of such defects is still qualitative and biased by subjective interpretations. Three-dimensional imaging techniques and novel anatomical reconstructions using statistical shape models (SSM) allow a more impartial and quantitative assessment of acetabular bone defects [1]. The objectives of this study are to define five clinically relevant parameters and to assess 50 acetabular bone defects in a quantitative way.

Alumina–alumina bearings are among the most resistant to wear in total hip replacement. Examination of their surfaces is one way of comparing damage caused by wear of hip joints simulated in vitro to that seen in explanted bearings. The aim of this study was to determine whether second-generation ceramic bearings exhibited a better pattern of wear than those reported in the literature for first-generation bearings. We considered both macro- and microscopic findings.

We found that long-term alumina wear in association with a loose acetabular component could be categorised into three groups. Of 20 specimens, four had ‘low wear’, eight ‘crescent wear’ and eight ‘severe wear’, which was characterised by a change in the physical shape of the bearing and a loss of volume. This suggests that the wear in alumina–alumina bearings in association with a loose acetabular component may be variable in pattern, and may explain, in part, why the wear of a ceramic head in vivo may be greater than that seen after in vitro testing.

Hydroxylapatite (HA) is widely employed as coating of cementless hip stems. Nevertheless there is a deficiency of long-term follow-up studies, and none, to our knowledge, with a ceramic on ceramic coupling, that it is important to avoid the effect of polyethylene wear on stem survival.

Between June 1990 and December 1991, 151 prostheses with an anatomic fully HA-coated cobalt-chrome stem, alumina bearing surfaces, and a threaded Ti-6Al-4V cup, were implanted in 147 consecutive patients (57 males, 90 females, average age 58 years). All were primary surgeries, there were no specific exclusions. Ten died for unrelated causes to the surgery, one died from postoperative complications; thirty nine of the surviving patients were lost to follow-up. The Merle D’Aubigné and Postel score was recorded before and after surgery at each review. An anteroposterior view and a frog-lateral view of the involved hip were taken at each follow-up review. The results were analysed by the Kaplan-Meier method to estimate the cumulative probability of revision.

In two cases, the prosthesis was completely removed with Gilderstone’s procedure because of septic loosening. Among the others, 10 cups required revision surgery for aseptic loosening, and 6 stems were revised for thigh pain. The mean Merle D’Aubigné rating improved from 10 before operation to 16.4. Bone stability was recorded in all cases but three in which there was a painfree fibrous stability. The Kaplan-Meier analysis at 12 years predicted asurvival rate for the prosthesis of 86% (95% CI 79 to 92), and for the stem of 93.8% (95% CI 89.7 to 98).

At 12 years the HA-coated stem has shown an overall good outcome while the threaded non HA-coated cup employed had a bad survival that had influenced the survival of the prosthesis. In conclusion we are confident to consider HA a viable and effective coating.

Aims: The aim of this study is to report the pre-clinical validation and clinical experience with modular neck primary prosthesis.

Introduction: Modular acetabular designs are widespread used in primary THA for their versatility while little experience is reported with modular femoral designs. Stem modularity could be useful when the anatomy is overthrown and for mini-incision approaches, providing an increased adaptability without any need for a large inventory or expensive custom made prostheses.

Methods: The fretting-corrosion behavior of the neck-stem coupling and the amount of particulate released under simulated physiological activities were investigated. In vitro tests were performed in Ringer’s solution loading the stem up to 20 millions cycles (i.e. 20 yrs) according to ISO 7206. From January 1995 to December 2001, 864 primary surgeries were performed with a modular stem. There were 458 women and 406 men; the mean age was 55 years (16–81 years). The main pre-operative diagnosis was primary arthritis (58.1%), the second CHD (22.2%). The stem survival was estimated by the Kaplan-Meier method.

Results: Evidence of primary corrosion was not found, conversely areas showing fretting damage were seen. The amount of fretted material was estimated in less than 1mg/year. Clinically 3 stems were revised, 2 for recurrent dislocation, 1 for stem subsidence, none for mechanical failure. At 6 years the estimated stem survival is 99.4%.

Conclusions: Modular stems have shown excellent clinical and mechanical behavior. The amount of fretting debris product is negligible taking that a stable prosthesis is likely to produce more than 10mg/year of metal debris.

Aims: The aim of this retrospective study is comparatively analysing cemented versus hydroxyapatite coated cementless þxation. A 10-year survival analysis of 2 patient cohorts operated by the same senior surgeons and with the same stem design was performed. Methods: Between 1990 and 2000, 1207 primary prostheses, 599 cemented and 608 cementless stems have been implanted. When mineral bone density and anatomic shape of the femur advised against inserting a cement-less stem a third generation cementing technique was chosen. In all cases an anatomic CoCr alloy stem and an alumina coupling were employed. Cementless stems were fully coated with hydroxyapatite. To provide homogeneity for preoperative diagnosis, only replacements for primary arthritis were considered. The remaining prostheses were 432 cemented and 366 cementless. The cumulative probability of revision for aseptic loosening of the stem was estimated by the Kaplan-Meier method. Results: 98.5% of the cemented stems and 96.7% of the cementless stems survived at 10 years, the difference between the 2 cohorts being statistically not signiþcant (p> 0.05). Conclusions: Using the same stem design and ceramic coupling, thus avoiding the confounding presence of polyethylene wears debris on study outcomes, allows for the reliable evaluation of stem þxation effectiveness. Noting that the evaluated survival rates are consistent with the literature, we are conþdent that at 10 years cementless stems performed as cemented.