NexGen® LPS mobile bearing total knee arthroplasty: 10-year results.

PURPOSE: Mobile bearing (MB) knee prostheses were designed to improve the performances of the total knee arthroplasties (TKA). The clinical superiority of MB prosthesis compared to its fixed bearing counterpart has remained elusive. This study prospectively evaluates the cumulative survivorship, clinical, radiographic results, and complications of a large series of MB TKAs in relation to patient age, sex, severity of arthritis, and patellar resurfacing. METHODS: This study evaluates the 5- to 10-year cumulative survival rate of the NexGen(®) LPS MB. Between 2000 and 2005, we performed a consecutive series of 332 MB, posterior-stabilized TKA in 249 patients (mean age 71.2 years, SD 6.9). The implants were clinically evaluated with the Hospital Special Surgery Knee Score (HSS-KS) and radiographically with the Knee Society Roentgenographic Evaluation System (KS-RES). The mean follow-up was 76.3 months (minimum 5 years). RESULTS: The HSS-KS improved from 55 pre-operatively to 86 at the end of follow-up. According to the KS-RES, the implants were anatomically aligned and progressive radiolucent lines appeared in four knees (1.2 %). The patella was selectively resurfaced in 162 of 332 knees. Patients with the patella resurfaced had better clinical results compared to those not resurfaced, but there was no difference in terms of survival. The cumulative survival rate was 98.4 % at 10 years (Kaplan-Meier's analysis). CONCLUSIONS: This MB implant provided reliable and durable clinical results with a survivorship of over 98 % at 10 years, in unselected patients regardless of age, sex, severity of disease, and patellar treatment.

Arthroscopic treatment of hip chondral defects: autologous chondrocyte transplantation versus simple debridement--a pilot study.

PURPOSE: To compare the effectiveness of simple arthroscopic debridement versus arthroscopic autologous chondrocyte transplantation (ACT) for the treatment of hip chondral lesions. METHODS: We carried out a controlled retrospective study of 30 patients affected by a post-traumatic hip chondropathy of the third or fourth degree, according to the Outerbridge classification, measuring 2 cm² in area or more. Of these patients, 15 underwent arthroscopic ACT, whereas the other 15 underwent arthroscopic debridement. The 2 groups were similar in age, sex, degree, and location of the pathology. All the patients were assessed before and after the procedure with the Harris Hip Score (HHS). RESULTS: In both groups the mean follow-up was approximately 74 months (range, 72 to 76 months). The mean size of the defect was 2.6 cm². The patients who underwent ACT (group A) improved after the procedure compared with the group that underwent debridement alone (group B). The mean HHS preoperatively was 48.3 (95% confidence interval [CI], 45.4 to 51.2) in group A and 46 (95% CI, 42.7 to 49.3) in group B (P = .428 [no significant difference]). The final HHS was 87.4 (95% CI, 84.3 to 90.5) in group A and 56.3 (95% CI, 54.4 to 58.7) in group B (P < .001 [significant difference]). CONCLUSIONS: This study indicates that an ACT procedure can be used in the hip for acetabular chondral defects. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Non-reducible knee dislocation with interposition of the vastus medialis muscle.

Irreducibility of the knee following complete dislocation is a rare event determined by the interposition of various capsulo-ligamentous structures in the joint space. Such cases often require urgent surgical treatment. We report the case of a healthy 70-year-old man with a sprain of the left knee that occurred after a sports trauma. The patient showed knee dislocation with multiple ligamentous injuries and articular block due to interposition of a portion of the vastus medialis muscle. After arthroscopic evaluation, we performed surgical treatment to free the muscle, regularize the medial meniscus and suture the posterior and medial capsule and ligaments; the cruciate ligaments were not treated. The most interesting aspect of the articular damage in this case was a wide detachment of the vastus medialis muscle with intra-articular dislocation. The decision to treat only the posterior lesions and allow the healing of the front ones by rehabilitation treatment was supported by full functional recovery and return to sports activity.

In vitro comparison between commercially and manually mixed antibiotic-loaded bone cements.

PURPOSE: The purpose of this study is the evaluation of the differences and, eventually, of the advantages or disadvantages of manual formulations with respect to industrial ones. METHODS: Medical-grade bone cements (Palacos R® and Palacos LV®), based on poly-methyl methacrylate (PMMA) and used clinically in several cemented prosthetic devices were manually enriched with gentamicin sulphate during preparation and then compared with a commercially-available, antibiotic-loaded cement (Palacos R+G®) by means of an in vitro antibacterial test (inhibition zone evaluation). The purpose of this study was to evaluate the differences and advantages or disadvantages, if any, of manual formulations compared to commercial ones. The use of a different antibiotic (vancomycin) alone or in addition to gentamicin-containing bone cements was also considered. RESULTS AND CONCLUSION: The commercial formulation produces an inhibition zone that is a bit larger and more regular than the manually mixed preparation. The vancomycin halo is smaller but clearer than the gentamicin halo. The addition of vancomycin to gentamicin-containing bone cements does not significantly increase the halo dimensions but could be an interesting strategy in the prevention of multiple and resistant infections.

Endo-Modell rotating-hinge total knee for revision total knee arthroplasty.

The goal of this study was to analyze the clinical and radiographic results and the survival rate of a series of rotating-hinge implants used for revision total knee arthroplasties in mild and severe instability. Between December 1991 and June 2004, fifty-three revision total knee arthroplasties were performed using the Endo-Modell (Waldemar LINK GmbH and Co, Hamburg, Germany) rotating-hinge prosthesis; 7 (13.2%) patients underwent partial revision of a previous Endo-Modell. All patients were evaluated preoperatively, 3 and 6 months postoperatively, and annually thereafter using the Hospital for Special Surgery (HSS) knee score and the Knee Society Roentgenographic Evaluation System (KS-RES). Mean follow-up was 155.2±40.1 months (range, 78-240 months), with 32 patients examined at the final follow-up. All HSS knee scores increased from preoperatively to last follow-up. No statistically significance differences were found in the HSS knee scores between septic and aseptic revisions and between total or partial revisions. Progressive radiolucent lines were detected in 8 (25%) patients. Implant failure occurred in 11 (20.7%) patients; the cumulative survival of the implants was 80.4% at 150 months for the final 32 patients. The authors recommend use of this implant for revision total knee arthroplasty, especially in patients with severe instability and bone loss.

Primary stability of a PGLA/Polydioxanone membrane for potential autologous chondrocyte implantation in the hip joint. A cadaveric study.

The purpose of this cadaveric study was to evaluate the primary stability of a membrane (resorbable polyglactin-910/poly-p-dioxanone) for autologous chondrocyte implantation (ACI) inserted by press-fit into defects in the femoral head and acetabulum. The stability of the membrane was evaluated after implantation in a cartilage defect on both sides of the joint in 12 hips in six cadavers. The hip was manually put through a full range of motion for 50 cycles after each lesion had been created and filled, starting with the acetabulum.
The implanted membranes showed stability in 83.3% of the acetabular defects and in 33.3% of the femoral defects after the 50 cycles. After an additional 50 cycles the acetabular membrane showed stability in a total of eight (67%) out of 12 acetabular lesions.
The results indicate that this membrane tissue is potentially stable in cartilage defects of the acetabulum, which may have clinical applications in autologous chondrocyte implantation.

Comparison of fixed and mobile-bearing total knee arthroplasty at a mean follow-up of 116 months.

BACKGROUND: The superiority of mobile-bearing total knee arthroplasty implants over fixed-bearing implants, or vice versa, is still debated. METHODS: A series of patients with similar clinical and radiographic characteristics were treated consecutively with 100 fixed-bearing followed by 100 rotating-platform implants. Patients underwent prospective clinical and radiographic evaluation. RESULTS: The mean duration of follow-up was 116 months (range, sixty-one to 144 months). Clinical, radiographic, and implant survival outcomes were compared. No significant differences between the mobile-bearing and fixed-bearing groups were found with respect to the clinical outcome or cumulative implant survival at the time of the latest follow-up. Three of the fixed-bearing implants and one of the rotating-platform implants had required revision surgery. CONCLUSIONS: No differences between mobile-bearing and fixed-bearing designs were demonstrated at a mean of 116 months of follow-up.

Results with 98 Endo-Modell rotating hinge prostheses for primary knee arthroplasty.

Rotating hinge knee prostheses have been developed as an advancement of the fixed hinge models. Some authors suggest that this type of prosthesis is associated with a greater risk of aseptic loosening because of the increased stresses to the bone-prosthesis interface; therefore, they are scarcely used as primary implants. The current authors evaluated of a series of 98 rotating hinge knee arthroplasties Endo-Modell (Waldemar LINK GmbH and Co, Hamburg, Germany) implanted for knee osteoarthritis. The Hospital for Special Surgery Knee Score and the Knee Society Score were used for the clinical and radiographic evaluation. Log-rank or Wilcoxon tests were used to test the statistical significances, and the Kaplan-Maier method was used to calculate the implant survival probability. After a medium follow-up of approximately 174 months, the clinical scores showed a statistically significant improvement from the pre- to postoperative period. The complication rate was high, and the cumulative implants survival rate was 88.7% at 1 year, 85.9% at 5 years, 79.8% at 10 years, and 75.8% at 15 years. The Endo-Modell rotating hinge implants demonstrated no significant risk of aseptic loosening, and the hinge was not a primary cause of failure. However, the overall failure rate was higher than that of unhinged implants; therefore, this prosthesis is recommended for cases of instability and revision rather than primary knee arthroplasty.

Rotating-hinge total knee for revision total knee arthroplasty.

Rotating-hinge knee implants are used for revision total knee arthroplasty in patients with severe ligament instability and bone loss. This study evaluated the outcomes of a series of rotating-hinge knees. Thirty-one NexGen Rotating Hinge Knees (Zimmer, Warsaw, Indiana) were implanted in 29 patients (2 bilateral), with an average age of 72.8 years. Indications for surgery were aseptic loosening (n=23), septic loosenings (n=4), tibiofemoral instability (n=3), and wear (n=1). The Hospital for Special Surgery Knee Score and the Knee Society Roentgenographic Evaluation System were used. Statistical and cumulative survival rate analyses were performed. Average follow-up was 60.3 months (range, 32-100 months). The Hospital for Special Surgery Knee Score results indicated statistically significant improvement; the total score increased from 65.5 preoperatively to 88.4 postoperatively. Average range of motion increased from 90.9° preoperatively to 114.4° postoperatively. Radiographs showed no periprosthetic bone fractures or implant ruptures. Radiolucent lines were found in 20 of 26 patients and were progressive in 2 (both revised). Complications occurred in 10 patients. The rigidity of the hinge may be associated with a risk of aseptic loosening due to the increased stress transfer to the bone from the prosthesis through the locked hinge. Rotating-hinge knee implants provided acceptable mid-term outcomes for revision knee surgery with ligamentous instability. They are not at higher risk for early loosening unless short tibial stems are used. The high percentage of failures is more related to the complex surgery and to the status of the patients than to the hinged mechanism.

Modular cementless cup for total hip arthroplasty: results at 4-year follow-up.

The aim is to perform the assessment of a modular cementless acetabular cup with a tapered internal design for all bearing couplings. In 190 unselected consecutive patients, 207 total hip arthroplasties were implanted. The implants were clinically and radiographically evaluated. Follow-up was 49.7 ± 8.1 months. The average Harris hip score improved from 55.5 ± 5.7 to 94.7 ± 3.4 (P < 0.05). All cups were well-positioned and stable. The Kaplan-Maier cumulative survivorship was 98.5 ± 0.8%. No significant differences have been noted in dividing patients according to the different liner materials (P < 0.005). The study, whose rationale is the novelty of this kind of implant, suggests the efficacy of the Delta-PF acetabular cup.

Adult congenital permanent bilateral dislocation of the patella with full knee function: case report and literature review.

Congenital permanent dislocation of the patella is a rare disorder of the knee joint in which the patella is permanently displaced, even in extension and is fixed on the lateral aspect of the femoral condyle. The dislocation is irreducible without surgical techniques. This rare condition is usually detected within the first decade of life, because of inability of active extension in the knee and impaired ability during walking. This report presents an unusual case of a 51-year-old man with bilateral congenital permanent dislocation of the patella. The pathology had never been treated because there were few symptoms. The patient presented with right knee pain caused by a fall on the knee during his work. The right knee was painful on the lateral side and the clinical signs were positive for pathology of the lateral meniscus, confirmed by MRI. The clinical and the imaging findings suggested a lesion of the lateral meniscus as the probable cause of the pain. Therefore we performed a knee arthroscopy, whose intra-operative findings confirmed the MRI findings. During the surgery we performed just a selective arthroscopic meniscectomy, without correcting patella dislocation, because the condition was unusually asymptomatic before the trauma.

Dislocation rate after hip arthroplasty within the first postoperative year: 36 mm versus 28 mm femoral heads.

Dislocation is a common and important complication of total hip arthroplasty (THA). Larger femoral heads may reduce the risk of dislocation and improve the range of movement. The aim of this study was to compare the relative risk (RR) of dislocation during the first year after THA between implants with 28 mm and 36 mm femoral heads. 198 consecutive hips with 28 mm femoral head (Group-28) and 259 hips with 36 mm femoral head (Group-36) were studied. The patients were assessed preoperatively and periodically using the Harris hip score (HHS) and radiographic analysis. The relative risk (RR) of dislocation was calculated. The average HHS significantly improved from a preoperative baseline to the last follow-up at 82.1 months (28 mm) and 44.3 months (36 mm). No statistically significant differences were revealed between the two groups for HHS results and complications (p>0.05), but the difference in RR of dislocation within the first year between the two groups was 7.85 (95% CI: 1.34-46.03), p=0.046.Although dislocation is multifactorial in etiology, the two groups were homogenous for all principal contributing factors except the diameter of the femoral head. Therefore, the use of 36-mm heads can reduce the risk of dislocation following THA by a factor of 8 compared to conventional 28 mm heads.

Operative Management of Sciatic Nerve Palsy due to Impingement on the Metal Cage after Total Hip Revision: Case Report.

This paper discusses a sciatic nerve palsy developed after a right total hip revision with a Burch-Schneider metal cage. A sciatalgic nerve pain appeared after surgery, while the palsy developed in about fifteen days. An electromyography showed the delay of the nerve impulse gluteal level. During the surgical exploration of the hip, a compression of the nerve on the metal cage was observed. The nerve was isolated, released from the fibrotic tissue and from the impingement, and was protected with a muscular flap. The recover from the pain was immediate, while the palsy recovered one month later.

Antibiotic-loaded cement in orthopedic surgery: a review.

Infections in orthopaedic surgery are a serious issue. Antibiotic-loaded bone cement was developed for the treatment of infected joint arthroplasties and for prophylaxes in total joint replacement in selected cases. Despite the widespread use of the antibiotic-loaded bone cement in orthopedics, many issues are still unclear or controversial: bacterial adhesion and antibiotic resistance, modification of mechanical properties which follows the addition of the antibiotic, factors influencing the release of the antibiotic from the cement and the role of the surface, the method for mixing the cement and the antibiotic, the choice and the effectiveness of the antibiotic, the combination of two or more antibiotics, and the toxicity. This review discusses all these topics, focusing on properties, merits, and defects of the antibiotic loaded cement. The final objective is to provide the orthopaedic surgeons clear and concise information for the correct choice of cement in their clinical practice.