Introduction and Objective

Local cartilage defects in the knee are painful and mostly followed by arthritis. In order to avoid impaired mobility, the osteochondral defect might be bridged by a synthetic compound material: An osteoconductive titanium foam as an anchoring material in the subchondral bone and an infiltrated polymer as gliding material in contact with the surrounding natural cartilage.

Total knee arthroplasty (TKA) disturbs patellar blood flow, an unintended accompaniment to TKA that may be a cause for postoperative anterior knee pain. We compared patellar blood flow before and after medial parapatellar arthrotomy to pre- and postoperative anterior knee pain scores to ascertain whether disrupted patellar blood flow correlates with anterior knee pain following TKA. Blood flow measurements were performed at full extension and at 30°, 60°, 90° and 110° of flexion prior to and after medial arthrotomy in 50 patients (21 male, 29 female; mean age 73.1±8.6 years) undergoing TKA. Anterior knee pain was assessed using the pain intensity numeric rating scale. A significant decrease in blood flow was detected at 60°, 90°, and 110° of flexion (p values: 0.00314,< 0.0001,< 0.0001 respectively). The medial arthrotomy did not have a statistically significant influence on patellar blood flow in the Students’ t-test (margin of significance p& #61603;0.05) Nineteen patients exhibited an average 14% (range 1%–54%) increase in patellar blood perfusion at knee flexions of 90° and 110° after medial arthrotomy (p value: 0.32) Prior to TKA, 16 of the 50 patients (32%) complained of anterior knee pain (average NRS 7.12, range 5–10). At 6-month follow up, 4 of the 16 patients (25%) complained of moderate anterior pain (average NRS 5.7, range 5–6), while 8 of 16 (50%) patients reported discomfort (average NRS 3.5, range 2–4) around the patella. No statistically significant correlation was found between intraoperative findings on patellar blood flow and the presence of anterior knee pain

Introduction: Ruptured anterior cruciate ligaments (ACL) are generally thought not to heal after treatment so that the ligament must be replaced by a graft. We developed and evaluated a surgical technique that restores knee stability using the self-healing capacity of the ruptured ACL.

Methods: The ACL was cut close to the femoral insertion in 14 sheep. The contralateral, nonoperated side served as the control. After microfracturing at the femoral foot print, the ACL was stabilized using the dynamic intraligamentary stabilization (DIS) technique. A strong intraligamentary suture was attached on the femoral side with a button and on the tibial side by means of an intraosseous spring-loaded screw with a preload of 85 N. In 7 of 14 sheep the ruptured ligament was covered with a collagen membrane. The joint was not immobilized postoperatively. Histological evaluation, magnetic resonance imaging (MRI) and biomechanical testing were performed after 3 months.

Results: Three days postoperative all animals showed no lameness and regularly used the operated leg. Macroscopically, all repaired ACLs appeared healed. Histological and MRI examinations confirmed the healing response of the ACL after DIS. The collagen membrane exhibited a more hypertrophic scare tissue reaction. Biomechanical testing showed an average increase of the operated anterior drawer 2.4 mm (range 0 mm – 4.5 mm) greater than on the control side. No lesions of the meniscus and cartilage were detected.

Conclusions: A ruptured ACL has the biological potential to heal after DIS in a sheep model. The surgical technique achieved a stable knee joint with free range of motion and full weight bearing during the healing period without signs of osteoarthritis or other intraarticular damage at follow up.

Introduction: Studies about the influence of patient characteristics on mechanical socket failure in THA apply different methodologies and reveal inconclusive results. In addition the fixation mode has rarely been in the focus of investigation.

Methods: We conducted a two-arm matched pairs case-control study assessing the influence of patient characteristics sex, age, weight, BMI, diagnosis, and activity level (Charnley classification) on the odds for mechanical socket loosening. The cemented and uncemented fixation mode was analyzed separately.

Results: 299 cases and 986 controls were included in the cemented study arm and 510 cases and 3000 controls in the uncemented arm. Women had reduced loosening odds for the cemented (OR=0.59, p=0.0024) and uncemented (OR=0.63, p=0.0001) fixation compared to men (OR=1). Each additional year the intervention was postponed reduced the loosening odds by about 2 % for cemented (OR=0.98, p=0.017) and uncemented (OR=0.98, p=0.0002) sockets. In cemented sockets the weight group of 73–82 kg had lower loosening odds (OR=0.63, p=0.017) than the lighter (OR> 0.92) and heavier (OR> 1.1) weight groups. There were no significant effects of weight in the uncemented group. In contrast, obese patients (BMI> 30) with uncemented sockets displayed elevated loosening odds (OR=1.41, p=0.034) compared to an insignificant effect in the cemented arm. Osteonecrosis was the only main pathology revealing elevated loosening odds (OR=1.27, p=0.049) but only in cemented sockets. The Charnley classification as an indirect proxy of activity revealed changing and insignificant effects.

Conclusions: Female sex and a delayed intervention have similarly protective effects on the odds for cemented and uncemented socket loosening. Whilst a certain body weight range has a significantly protective effect in cemented sockets the more important finding is the significantly increased risk for uncemented socket loosening in obese patients. Patients with osteonecrosis are the only etiologic group at a significantly increase risk for socket loosening, but only with a cemented fixation. The Charnley classification as a surrogate for activity level had no influence on loosening risks in either socket fixation mode. Level of Evidence: Level III (case-control study)

Aims: The study was carried out to describe the long-term development of relevant clinical parameters after total hip arthroplasty (THA). Methods: Primary and follow-up data from 26‘019 THA from 9‘801 men and 11‘144 women were monitored across a postoperative period of 15 years. The population was described as one group and according to Charnley. Results: Patients experienced significant pain relief and major improvements in mobility and hip motion. The 5% of patients with preoperatively no or mild hip pain grew to 90–95% postoperatively and was 85% 15 years later. The 8% patients with a preoperatively free walking time greater 30 min. increased to 60% postoperatively. 15 years after the THA 60% managed free walking times up to 30 minutes. A hip flexion greater 90 degrees was preoperatively possible for 22% of the patients, postoperatively for 78%. Up to 94% judged the outcome as excellent or good after one year and 84% after fifteen years. The prevalence of radiographically loose stems increased from 0.87% to 14.44% 14 years postoperatively. Simultaneously, the prevalence of radiographically loose cups increased from 0.8% to 16.67%. Conclusions: A THA delivers significant gain in mobility, hip motion and pain relief and a high number of satisfied patients. A constant deterioration of abilities and satisfaction could be observed beginning three to five years after the primary operation. However, 15 years postoperatively, these abilities were still superior to the preoperative levels. A steady increase in radiographically loose components was noted. It took patients three to five years to reach their maximum outcome.

Aims: New threshold levels for a classification of Harris hip score (HHS) with respect to patient satisfaction after total hip arthroplasty (THA) were calculated. Methods: Registry data from four follow-up intervals (< =3, 3–6, 6–9, > 9 years) from 3824 female and 4002 male patients were analyzed and optimal agreements between patient satisfaction and HHS classes were calculated using kappa values (κ). Patients were classified into Charnley classes A and B/C. HHS outcome was transformed into a binary format (positive, negative). Results: Associations between outcomes of the complete patient group using the normal HHS-classification (100, 90, 80,< 70) were weak (κ≤ 0.42). For a binary outcome classification with positive (excellent, good) and negative (fair, poor) results, associations improved especially for Charnley A patients (κ=0.46). Using the recalibrated HHS, the separation of patients in Charnley A vs. B/C and a binary outcome classification resulted in clear associations between HHS results and patient evaluation in both groups A (κ=0.527) and B/C (κ=0.424). The new thresholds were 95 (good), 75 (fair) and 65 (poor) for Charnley A and 95, 75 and 60 for Charnley B/C respectively. Conclusions: The newly calibrated HHS can differentiate between a patient perceived positive and a negative outcome in Charnley A and B/C patients. The differentiation between these two groups is essential since Charnley B and C patients have, by definition, an inferior mobility compared to Charnley A patients which can render a successful THA as fair and poor in many of those patients if the traditional HHS classification is applied.

We analysed follow-up data from 18 486 primary total hip arthroplasties performed between 1967 and 2001 to assess the validity of clinical procedures in diagnosing loosening of prosthetic components. Sensitivity, specificity and predictive values were estimated with the radiological definition of loose or not loose as the ‘gold standard’.

The prevalence of acetabular loosening increased from 0.6% to 13.9% during the period of the study and that of femoral loosening from 0.9% to 12.1%. Sensitivities and positive predictive values were low, suggesting that clinical procedures could not replace radiological assessment in the identification of loose prostheses. Specificities and negative predictive values were constantly above 0.86. The possibility of there being a prosthesis which is not loose in asymptomatic patients was consequently very high, particularly during the first five to six years after operation.

The necessity of periodic clinical and radiological follow-up examinations of asymptomatic patients during the first five to six years after operation remains questionable. Symptomatic patients, however, require radiological assessment.

In this prospective, randomised study, we have compared the wear rate of cemented, acetabular polyethylene cups articulating with either a 22 mm or a 32 mm cobalt-chromium head. We evaluated 89 patients who had a total of 484 radiographs. The mean follow-up period was 71.4 months (SD 29.1). All the radiographs were digitised and electronically measured.

The linear wear rate was significantly higher during the first two years and decreased after this period to a constant value. We suggest that this is partly due to a ‘run-in’ process caused by irregularities between surfaces of the cup and head and an initial plastic deformation of the polyethylene. The mean volumetric wear was 120.3 mm³/year for the 32 mm head, which was significantly higher than the 41.5 mm³/year for the 22 mm heads. The mean linear wear rate was not significantly different. We were, however, unable to find radiological signs of osteolysis in the patients who had higher wear rates.

We reviewed 508 consecutive total hip replacements in 370 patients with old developmental dysplasia of the hip, to relate the amount of leg lengthening to the incidence of nerve palsies after operation. There were eight nerve palsies (two femoral, six sciatic), two complete and six incomplete.

We found no statistical correlation between the amount of lengthening and the incidence of nerve damage (p = 0.47), but in seven of the eight hips, the surgeon had rated the intervention as difficult because of previous surgery, severe deformity, a defect of the acetabular roof, or considerable flexion deformity. The correlation between difficulty and nerve palsy was significant (p = 0.041). We conclude that nerve injury is most commonly caused by direct or indirect mechanical trauma and not by limb lengthening on its own.

To analyse the value and accuracy of preoperative planning for total hip replacement (THR) we digitised electronically and compared the hand-sketched preoperative plans with the pre- and postoperative radiographs of 100 consecutive primary THRs.

The correct type of prosthesis was planned in 98%; the agreement between planned and actually used components was 92% on the femoral side and 90% on the acetabular side. The mean (± SD) absolute difference between the planned and actual position of the centre of rotation of the hip was 2.5 ± 1.1 mm vertically and 4.4 ± 2.1 mm horizontally. On average, the inclination of the acetabular component differed by 7 ± 2° and anteversion by 9 ± 3° from the preoperative plans. The mean postoperative leg-length difference was 0.3 ± 0.1 cm clinically and 0.2 ± 0.1 cm radiologically. More than 80% of intraoperative difficulties were anticipated.

Preoperative planning is of significant value for the successful performance of THR.