There is renewed interest in unicondylar knee replacements (UKR) to meet the increasing demand for less invasive surgical procedures for knee arthroplasty. UKR survivorship exceeds 85% at 10 years, with unconstrained (round-on-flat) designs showing significantly better survivorship than conforming designs. However, round-on-flat articulation shave the potential for poor wear performance and more conforming, mobile-bearing UKR designs have been advocated. The purpose of this study was to evaluate the wear performance of unconstrained UKR polyethylene bearings retrieved at revision knee arthroplasty.

Forty-two UKR (eight designs) were retrieved from 26 female and 16 male patients. Patient age averaged 73+10 (45–89) years and time in-situ averaged 7+4 (1–19) years. Revision reasons included loosening (45%), progressive osteoarthritis (17%), polyethylene wear (14%), instability (5%), and other (19%). Retrospective radiographic review of radiolucent lines and component alignment was completed. Polyethylene damage (severity score, 0–3) and location were measured using optical microscopy and digital image analysis.

81% of the polyethylene inserts had a concave deformation located on the central or posterior third of the articular surface, consistent with damage due to femoral component articulation. Abrasive damage on 29 (69%) inserts was consistent with impingement between the polyethylene and extra-articular cement or bone. There was delamination in the central region of 7 (17%) inserts and on the extreme posterior rim of 3 (7%) inserts. Severity score averaged 2.0+1.2 for abrasion and 0.5+1.0 for delamination. Radiographic component position was correlated with abrasive polyethylene damage.

Despite initial tibiofemoral incongruity and concerns of high contact stress, round-on-flat UKR offers a durable knee arthroplasty. Delamination was infrequent and did not correlate with time in-situ. Rather, polyethylene cold flow increased the contact area during in-vivo function. Rigorous attention to cement technique and component position may reduce the incidence of abrasive damage on UKR polyethylene inserts.

There is renewed interest in unicondylar knee replacements (UKR) to meet the increasing demand for less invasive surgical procedures for knee arthroplasty. UKR survivorship exceeds 85% at 10 years, with unconstrained (round-on-flat) designs showing significantly better survivorship than conforming designs. However, round-on-flat articulations have the potential for poor wear performance and more conforming, mobile-bearing UKR designs have been advocated. This study evaluates the wear performance of unconstrained UKR polyethylene bearings retrieved at revision knee arthroplasty.

Forty-two UKR with fixed polyethylene tibial bearings were retrieved. Patient age and time in-situ averaged 73 (45–89) years and 7 (1–19) years, respectively. All knees had intact cruciate ligaments at index surgery. Revision reasons included loosening (45%), progressive arthritis (17%), polyethylene wear (17%), instability (5%), and other (17%). Retrospective radiographic review of radiolucent lines and component alignment was completed using Knee Society guidelines. Polyethylene articular damage size (% of articular surface area), location and damage mode incidence were measured using microscopy and digital image analysis.

Damage area was centrally located and averaged 65%+22%. The largest damage areas consisted of abrasion (19%) and scratching (17%). Revision for loosening or wear was significantly correlated with greater damage area (Spearman Correlation, p=0.049). The incidence of scratching, pitting and abrasion each exceeded 70%, including 29 inserts with peripheral abrasive damage consistent with impingement between the polyethylene and extra-articular cement or bone. Anterior damage location and abrasion were significantly correlated with component position (p< 0.001). Concave surface deformation due to femoral component contact was externally rotated (24 inserts), consistent with tibial external rotation relative to the femoral component, neutrally aligned (11 inserts), internally rotated (4 inserts), and indeterminate (3 inserts).

Despite initial tibiofemoral incongruity and concerns of high contact stress, round-on-flat UKR offers a durable knee arthroplasty. The relatively unconstrained tibiofemoral articulations allowed freedom of placement on the resected bone surfaces and a range of tibio-femoral rotation during activity, as demonstrated by the rotated concave surface deformations. Such deformation may reduce polyethylene contact stresses by increasing the tibio-femoral contact area. However, similar to retrieved mobile bearing UKR which show a 63% incidence of impingement, abrasive damage on these fixed bearing UKR has consequences for polyethylene debris generation and the transmission of shear forces to the bone-implant interface. Rigorous attention to conventional and minimally invasive surgical technique, including cement fixation and component position, is needed to reduce the incidence of abrasive polyethylene damage.

Introduction: Risk-profiling of patients in hip arthroplasty to prepare for perioperative complications is becoming more important. Materials and Methods Major complications (haematoma, cardiovascular complication, deep venous thrombosis, pulmonary embolism, joint infection, injuries of neurovascular structures and pneumonia) following 29994 hip arthroplasties occurring within the postoperative hospitalisation period have been documented based on a standardised protocol used for external quality assessment in Germany. Using logistic regression, the influence of potential risk factors was assessed for their significance on postoperative complications and univariate analysis was used to assess this influence on every single major complication. The influence of patient age and the surgery time on major complications were calculated using ANOVA.

Results: Major perioperative complications occurred in 7,26 per cent. Haematomas were reported in 3.22, cardiovascular complications in 1.55, joint infections in 0.94, injuries of neuro-vascular structures in 0,63, deep venous thrombosis in 0.37, pulmonary embolism in 0.26 and pneumonia in 0.28 per cent of all cases. Patient age, length of surgery and allogeneic blood transfusion significantly increased the rate of major perioperative complications. Increased patient age increased the risk for all major complications but neuro-vascular injuries. Increased surgery time elevated the risk for all major complications except haematoma. Allogeneic blood transfusions were associated with an elevated risk for all major postoperative complications except deep venous thrombosis. In contrast, autologous blood transfusions did not increase the risk for suffering a postoperative complication. Surprisingly, gender did not have a significant influence on the occurrence of immediate postoperative complications. Conclusions Allogeneic blood transfusion, increased age and surgery time contribute to an elevated incidence of perioperative complications following hip arthroplasty.

Introduction: Minimal-invasive techniques in total joint replacement are perceived to reduce soft tissue trauma. In TKR, reduced exposure during surgery bares the risk of component malpositioning. Therefore we have combined minimal invasive surgical techniques with non-CT based navigation in TKR. The purpose of this observational study is to describe first results of a controlled observational study comparing minimal invasive navigated total knee arthroplasty (MINI-NAV-TKR) to open navigated total knee arthroplasty (NAV-TKR) with respect to component positioning, surgery time and immediate postoperative complications.

Materials and Methods: From June to September 2004, 26 MINI-NAV-TKR and 33 NAV-TKR have been performed by five surgeons in an unselected group of patients. In both groups, preoperative deformation of the mechanical leg axis was compared to postoperative mechanical leg axis using total one-leg standing radiographs. To control the safety and reproducibility of both procedures, time of surgery and postoperative complications were compared among both groups.

Results: Given informed consent, 17 females and 9 males received 26 MINI-NAV-TKR, mean age was 71,06 years (ranging from 56,24 years to 84, 35 years), mean BMI was 28,8 kg/m2 and preoperative mechanical leg axis ranged from 18o varus to 16 o valgus. In NAV-TKR group, 12 males and 21 females at a mean age of 68,75 (range 51,97 to 86,73 years) received 33 TKR, mean BMI was 30,6 kg/m2 and preoperative mechanical axis ranged from 11 varus to 20 valgus. Postoperative radiographic leg alignment in the MINI-NAV-TKR group ranged from 1 degree valgus to 3 degree varus mechanical axis as compared to the NAV-TKR that ranged from 1 valgus to one outlayer of 4 degree varus. Time of surgery significantly differed among the groups (mean time Mini-NAV-TKR 115,23 min versus mean time NAV-TKR 98,15 minutes, p=0,002). In the MINI-NAV-TKR group 1 postoperative pin-infection and one conversion to an open procedure have been reported, in the NAV-TKR group 2 hematomas have been described.

Conclusion: Despite increased mean time of surgery in the MINI-NAV-TKR group, component positioning and complications are comparable between both groups. These preliminary results indicate, that MINI-NAV-TKR combined with navigation is a safe and reproducible method.

Introduction: Risk-profiling of patients in knee arthroplasty to prepare for postoperative complications is becoming more important.

Materials and Methods: Major complications (hematoma, cardio-vascular complication, deep venous thrombosis, pulmonary embolism, joint infection and pneumonia) following 17644 knee arthroplasties occurring within the postoperative hospitalization period have been documented based on a standardized protocol used for external quality assessment in Germany. Using logistic regression, the influence of potential risk factors were assessed for their significance on postoperative complications and uni-variate analysis used to assess this influence on every single major complication. The influence of patient age and the surgery time on major complications were calculated using ANOVA.

Results: Major postoperative complications occurred in 7.22 per cent with hematoma in 2.89, cardio-vascular complications in 1.79, deep venous thrombosis in 1.23, pulmonary embolism in 0.23, joint infection in 0.82 and pneumonia in 0.25 per cent. Patient age, surgery time, gender, high classification according to the American Association of Anesthesiologists, allogeneic blood transfusion and lateral release significantly increased the rate of postoperative complications. Males are more prone to suffer from hematoma, joint infection and pneumonia in the immediate postoperative course. Females are more endangered for deep venous thrombosis. Extended surgery time increased the rate of hematoma and infection, increased patient age elevated the rate of hematoma, cardiovascular complication and pneumonia. Alloge-neic blood transfusion increased the risk of all major complications except deep venous thrombosis.

Conclusions Male gender, allogeneic blood transfusion, increased age and surgery time elevate immediate postoperative complications following knee arthroplasty.

Early revision after total knee arthroplasty (TKA) is fortunately uncommon. However, instability and lack of fixation are common early failure mechanisms. Cement techniques utilizing lavage and multiple drill hole interdigitation of the resected tibial surface can reduce micromotion and produce reliable tibial component fixation. This study looks at clinical failure mechanisms, cement technique and polyethylene damage in patients needing early revision of cemented TKA.

PCL-retaining TKA with cement fixation was performed on > 1000 patients at a single institution. Cement techniques varied with surgeon, with some using lavage and drill hole preparation of the resected surface and others electing to cement the surface “as cut”. Seventeen patients were revised within three years of follow-up. Revision reasons included loosening (41%), instability (18%), infection (24%), pain (12%), and malposition (6%). Prospective outcome scores, radiographic data, revision reasons, and polyethylene wear were compared.

Pre-revision pain and function scores gradually decreased back to pre-operative levels. Leg alignment averaged 7° varus (nine patients) and 12° valgus (eight patients) pre-operatively and 5° valgus at pre-revision. Tibial radiolucent lines were present medially only in nine knees and medially and laterally in four knees. The majority of patients revised for loosening had a tibial component cemented onto the “as cut” bone without additional preparation. Damage covered 32%-85% of the polyethylene articular surface. Scratching and pitting were significantly correlated (p< 0.05) with shorter in-situ time and revision for instability and loosening. Alignment and outcome scores were not correlated with damage.

In this series of cemented TKA, loosening and instability accounted for 59% of the early failure, similar to the incidence previously reported for cementless TKA. Cement technique and component positioning, not polyethylene wear, were the primary contributing factors. Attention to ligament balancing and achieving better tibial component fixation is needed to further limit the incidence of early failure after cemented TKA.

Aims: Aim of this study was to evaluate the clinical and radiological results after operative treatment of congenital clubfoot by the Cincinnati-approach

Methods: Between 1996– 2000 52 children with congenital clubfoot were operated with a peritalar release by using the Cincinnatti approach. 35 of them were male, 17 female. 24 had clubfeet on both sides. The age at operation was 3–17 months (mean 5,3 months). The age at follow up was 24–90 months (mean 58 months). In the follow-up at least 2 years after operative treatment the results were analysed by the score of McKay. In addition we evaluated the radiographs by the standard method of Simons.

Results: In the postoperative clinical evaluation using the McKay-Score: we found in 35% excellent, 41% good, 21% fair, 2% poor, 1% bad results. The Simons-Score was used to evaluate the radiographic postoperative results. The talocalcaneal angle a.p. was in 19% < 20° (= incomplete correction), in 76% between 20° and 40° (= normal) and in 5% > 40° (= overcorrection). The talo-calcaneal angle lateral was in 8% < 30° (= incomplete correction), in 82% between 30° and 50° (= normal) and in 10% > 50° (= overcorrection). The position of the navicular bone in the apview was in 65% 0 (= normal), in 20% +1/+2 (= overcorrected but satisfactory), in 3% +3/+4 (= marked overcorrection, not satisfactory) and in 12% (−) (= incomplete correction).

Conclusion: In conclusion by using this protocol we could show a high frequency of satisfactory results concerning function and cosmetics.