Comparative Cost Analysis of Four Different Computer-Assisted Technologies to Implant a Total Knee Arthroplasty over Conventional Instrumentation.

Several computer-assisted technologies, such as navigation and robotics, have been introduced to Total Knee Arthroplasty (TKA) in order to increase surgical precision and reduce complications. However, these technologies are often criticized due to the increased costs and effort associated with them; however, comparative data are missing. The aim of the present study was to evaluate differences in intraoperative workflows and the related perioperative cost-profiles of four current computer-assisted technologies, used to implant a TKA, in order to gain a comparison to conventional instrumentation. For the cost analysis, additional preoperative imaging and instruments, increased operating room (OR) and planning-time, and expenditures for technical support of the equipment and disposals were calculated, in comparison to conventional TKA, for (1) standard computer-navigation, (2) patient specific instruments (PSI), (3) image-based robotic assistance, and (4) imageless robotic assistance. Workflows at four expert centers which use these technologies were reviewed by an independent observer. The total cost calculation was based on a 125 TKA per year unit in Switzerland. Computer-navigation resulted in 14 min (+23%) increased surgery time and, overall, USD 650 in additional costs. PSI technology saved 5 min (8%) OR time but it created USD 1520 in expenditures for imaging and disposals. The image-based robotic system was the most expensive technology; it created overall additional costs of USD 2600, which predominately resulted from technical support, disposals, the CT-Scan, and 14 min of increased OR time. The imageless robotic assistance resulted in the largest increase in OR-time, as it resulted in an additional 25 min (+42%) on average. Overall, additional costs of USD 1530 were calculated. Every one of the assistive technologies in this study increased the total cost of TKA when compared to a conventional technique, and the most important variables, related to cost, were technical support and additional disposables. The longer surgical times and additional surgical trays required for the techniques had a marginal effect on overall costs. This comparative cost analysis gives valuable information for future efforts to calculate the real costs of these technologies and the subsequent return on investment of each technique.

CT-based patient-specific instrumentation for total knee arthroplasty in over 700 cases: single-use instruments are as accurate as standard instruments.

PURPOSE: Efforts in total knee arthroplasty are made to improve accuracy for a correct leg axis and reduce component malpositioning using patient-specific instruments. It was hypothesized that use of patient-specific instruments (vs. computer-navigated and conventional techniques) will reduce the number of outliers. Our second hypothesis was that single-use instrumentation will lead to the same accuracy compared to patient-specific instruments made of metal. METHODS: 708 primary total knee arthroplasties between 2014 and 2018 using computer tomography (CT)-based patient-specific cutting block technique and a preoperative planning protocol were retrospectively reviewed. Preoperative data [hip-knee-angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), tibial slope, femoral component flexion] was compared to postoperative performed standard radiological follow-up X-rays. Differences of > 3° between measurements were defined as outliers. RESULTS: Overall 500 prostheses using standard instrumentation and 208 prostheses using single-use instruments were implanted. Preoperative HKA axes (- 1.2°; p < 0.001), femoral component flexion (Δ 0.8°, p < 0.001), LDFA (Δ - 1.5°, p < 0.001), MPTA (Δ - 0.5°, p < 0.001) and tibial posterior slopes (Δ 0.5°, p < 0.001), respectively, were different from postoperative axes. More outliers occurred using standard (vs. single-use) instruments (p < 0.001) regarding postoperative HKA (ranges of standard- vs. single-use: instruments: HKA 178.0°-180.5° vs. 178.0°-180.5°, femoral component flexion 0.0°-6.0° vs. 0.0°-4.5°, LDFA 90.0°-91.0° vs. 90.0°-90.0°, MPTA 90.0°-90.0° vs. 90.0°-90.0°, tibial posterior slope - 10° to 10° vs. - 1° to 10°). No differences were seen for other angles measured. Comparing both systems, total number of outliers was higher using standard (8%) vs. single-use instruments (4.3%). CONCLUSION: This study shows a high accuracy of CT-based patient-specific instrumentation concerning postoperative achieved knee angles and mechanical leg axes. Single-use instruments showed a similar accuracy. LEVEL OF EVIDENCE: III.

A novel augmented reality-based surgical guidance system for total knee arthroplasty.

INTRODUCTION: Many of the functional complications that arise after total knee arthroplasty (TKA) are caused by a non-optimal balance of the knee after surgery. Over the past 20 years, technology has been used in the Operating Room (OR) to help improve precision and balance. The results of Computer-Assisted Surgery (CAS) and robotic systems show improved accuracy regarding implant positioning but a relatively small improvement in patient-reported outcomes and implant survival compared to conventional TKA. Recently, Augmented Reality (AR) has been proposed as a technology that could improve accuracy in orthopaedic surgery, providing a more efficient and cost-effective solution. MATERIALS AND METHODS: This article describes a novel AR-based surgical guidance system that measures intra-operatively the effect of prosthesis alignment and positioning on soft tissue balance. The system is integrated in a pair of smart glasses and two small sensors and displays surgical targets directly in the field of view of the surgeon. RESULTS: The system has been used in a limited number of cases. While the preliminary experience has been positive, clinical research is ongoing to confirm to confirm the performance of the system and the impact on clinical outcomes. CONCLUSION: Augmented Reality can be a valuable tool to improve accuracy in TKA. The use of smart glasses and integrated sensors improves the efficiency of the procedure, particularly when coupled with single-use instrumentation. A novel protocol for soft tissue assessment allows for a 3-dimensional evaluation of the ligaments and a better measurement of the effect of tibial rotation.

Bone autografting in medial open wedge high tibial osteotomy results in improved osseous gap healing on computed tomography, but no functional advantage: a prospective, randomised, controlled trial.

PURPOSE: Medial open wedge high tibial osteotomy (owHTO) is a valuable surgical technique used to manage medial degeneration in varus knees. Iliac crest autograft is considered the gold standard gap-filler. It was hypothesised that iliac crest autograft promotes gap healing and improves functional outcome in owHTO. METHODS: Between 2005 and 2009, patients scheduled to undergo owHTO stabilised by a medial locking compression plate were randomised to undergo owHTO either with iliac crest autograft (group A) or without bone void filler (group B). Pre- and postoperative leg axes were recorded. At 3 and 12 months postoperatively, the healing of the osteotomy gap was measured as a percentage on CT images, and functional scores were recorded. RESULTS: There were 15 patients in group A, and 25 in group B. The groups were similar in age, sex ratio, knee varus deformity, body mass index, and smoking status. Group A and B had similar preoperative varus (6.9° vs. 7.6°) and postoperative valgus (2.2° vs. 3.0°). Compared with the control group, group A had a significantly greater degree of osseous gap healing after 3 months (40.1% vs. 10.8%, p = 0.045) and 12 months (91.5% vs. 59.1%, p ≤ 0.001). Multiple linear regression analysis found that bone grafting was an independent promoting factor for gap healing, while increased preoperative varus was an independent retardant factor at 3 months (p = 0.004 and p = 0.002, respectively) and 12 months (p ≤ 0.001 and p = 0.003, respectively). Younger age was a promoting factor for gap healing on CT at 3 months (p ≤ 0.001), but not at 12 months. No correlations were found between bone healing and functional outcome, body mass index, or smoking status. CONCLUSIONS: Iliac crest autograft significantly increases healing of the osteotomy gap after owHTO. Increased preoperative varus and older patient age are independent factors that delay early healing of the osteotomy. However, no functional advantage was found at 3 or 12 months postoperatively. Therefore, routine use of iliac crest autograft cannot be recommended. LEVEL OF EVIDENCE: II.

Prevalence and quantification of contamination of knitted cotton outer gloves during hip and knee arthroplasty surgery.

INTRODUCTION: Knitted cotton outer gloves offer protection against surgical glove perforation and provide improved grip on instruments. These gloves absorb blood and other fluids during surgery, and may therefore also accumulate contaminating bacteria. To date, there is no published data on microbial contamination of such gloves during surgery. METHODS: Knitted cotton outer gloves used in primary and revision hip and knee arthroplasty from two Swiss hospitals were analysed by quantitative bacteriology. Samples were subjected to sonication and vortexing, followed by membrane filtration of the sonicate. Membranes were incubated under aerobic and anaerobic culture conditions, respectively, for 21 days. Total microbial load for each pair of gloves was determined by colony-forming units (CFU) count. Strain identification was performed with MALDI-TOF. RESULTS: A total of 43 pairs of gloves were collected from continuous series of surgeries. Under aerobic culture conditions, total CFU counts ranged 0-1103, 25 (58%) samples remaining sterile, and 4 (9%) yielding > 100 CFU. Under anaerobic culture conditions, total CFU counts ranged 0-3579, 22 (51%) samples remaining sterile, 6 (14%) yielding > 100 CFU. The only covariate significantly associated with the level of contamination was the provider hospital (p < 0.0001 for aerobic and p = 0.007 for anaerobic cultures). Strain identification revealed only skin commensals, mainly coagulase-negative staphylococci and Propionibacterium spp. CONCLUSION: While contamination of surgical latex gloves is a well-known issue, no study has examined so far contamination of knitted cotton outer gloves. No or very low microbial contamination could be identified in the majority of the knitted cotton outer gloves assayed. However, a relevant proportion showed contamination far higher than estimated minimal thresholds for implant-associated infection. Clinical relevance of these findings remains to be established.

The tibial-tubercle trochlear groove distance in patients with trochlear dysplasia: the influence of the proximally flat trochlea.

PURPOSE: Increased tibial tubercle trochlear groove distance (TT-TG) is frequently associated with trochlear dysplasia (TD). Since the trochlear groove appears more distally in patients with TD compared to controls, it is unknown whether TT-TG might be comparable and meaningful. METHODS: Fifty patients with TD were retrospectively analysed and compared to 52 age- and gender-matched patients (CG). TT-TG was measured on transverse MR images, as the distance between the trochlear groove of minimal 2 mm depth proximally and the centre of the patellar tendon at its distal insertion. The height of the femoral reference point above joint line was recorded for both groups. TT-TG measurement was repeated in CG using the first (P25), second (P50) and third quartile (P75) above joint line of TD. RESULTS: Patients with TD had a significantly smaller vertical distance between the most proximal trochlear deepening and the femorotibial joint line (20.6 mm, range 10.3-30.9) compared to CG (33.8 mm, range 25.4-41.1; p < 0.001). TT-TG values measured at 20 mm (P50) and 15 mm (P25) proximal to the femorotibial joint line were significantly smaller compared when measured with the most proximal reference point [1.8 mm (95 % CI 1.3-2.3, p < 0.001) and 2.4 mm (95 % CI 1.9-3.0, p < 0.001)] in CG. The inter-rater reliability was excellent (ICC 0.99). CONCLUSION: TT-TG distance depends significantly on the femoral reference point. Since the trochlear groove is seen more distally in patients with TD compared to controls, TT-TG of the patients with highest risk of recurrent patellar instability might be underestimated. LEVEL OF EVIDENCE: Diagnostic study, Level I.

Complications after epiphyseal reconstruction of the anterior cruciate ligament in prepubescent children.

PURPOSE: Reconstruction of the anterior cruciate ligament (ACL) remains a major concern in the prepubescent, skeletally immature patient with wide open growth plates. Different surgical techniques have been proposed. This study reports the results and complications of ACL reconstruction in young children using an all epiphyseal technique. METHODS: Between 2006 and 2010, 12 patients (10-13 years, median 12.1 years) underwent epiphyseal primary ACL reconstruction, with a total of 13 knee procedures. Patients were assessed retrospectively with a median follow-up of 54 months (range 39-80 months) consisting of a clinical examination, instrumented arthrometer testing and radiological analysis. Functional status was assessed using the Lysholm knee score, Tegner activity scale and IKDC-2000 form. RESULTS: According to the IKDC examination form, five knees were rated as normal, six near normal and two abnormal. The median IKDC score at follow-up was 88.5 points (range 75-99 points). The mean side-to-side difference in KT-1000 ligament laxity testing was 1.5 mm (±2.5 mm). In two patients, reoperation was necessary due to graft failure. Two patients developed significant leg length inequality; one with 20 mm overgrowth and varus malalignment after re-reconstruction and the second developed arthrofibrosis and overgrowth of 16 mm. Four patients had minor limb length discrepancy ranging between +5 and +10 mm; no growth arrest was noted. One patient with an intact but slightly elongated graft required a meniscal suture 34 months after ACL reconstruction following a traumatic medial meniscal lesion. CONCLUSION: Despite using the epiphyseal technique in ACL reconstruction, relevant growth discrepancy can occur. Thereby, overgrowth rates appear to potentially pose a major clinical problem, which has remained unreported so far. Overall, there is a considerable high risk of complications in this patient group. LEVEL OF EVIDENCE: IV.

Complex Osteotomies of Tibial Plateau Malunions Using Computer-Assisted Planning and Patient-Specific Surgical Guides.

The accurate reduction of tibial plateau malunions can be challenging without guidance. In this work, we report on a novel technique that combines 3-dimensional computer-assisted planning with patient-specific surgical guides for improving reliability and accuracy of complex intraarticular corrective osteotomies. Preoperative planning based on 3-dimensional bone models was performed to simulate fragment mobilization and reduction in 3 cases. Surgical implementation of the preoperative plan using patient-specific cutting and reduction guides was evaluated; benefits and limitations of the approach were identified and discussed. The preliminary results are encouraging and show that complex, intraarticular corrective osteotomies can be accurately performed with this technique. For selective patients with complex malunions around the tibia plateau, this method might be an attractive option, with the potential to facilitate achieving the most accurate correction possible.

Evaluation of a virtual-reality-based simulator using passive haptic feedback for knee arthroscopy.

PURPOSE: The aim of this work is to determine face validity and construct validity of a new virtual-reality-based simulator for diagnostic and therapeutic knee arthroscopy. METHODS: The study tests a novel arthroscopic simulator based on passive haptics. Sixty-eight participants were grouped into novices, intermediates, and experts. All participants completed two exercises. In order to establish face validity, all participants filled out a questionnaire concerning different aspects of simulator realism, training capacity, and different statements using a seven-point Likert scale (range 1-7). Construct validity was tested by comparing various simulator metric values between novices and experts. RESULTS: Face validity could be established: overall realism was rated with a mean value of 5.5 points. Global training capacity scored a mean value of 5.9. Participants considered the simulator as useful for procedural training of diagnostic and therapeutic arthroscopy. In the foreign body removal exercise, experts were overall significantly faster in the whole procedure (6 min 24 s vs. 8 min 24 s, p < 0.001), took less time to complete the diagnostic tour (2 min 49 s vs. 3 min 32 s, p = 0.027), and had a shorter camera path length (186 vs. 246 cm, p = 0.006). CONCLUSION: The simulator achieved high scores in terms of realism. It was regarded as a useful training tool, which is also capable of differentiating between varying levels of arthroscopic experience. Nevertheless, further improvements of the simulator especially in the field of therapeutic arthroscopy are desirable. In general, the findings support that virtual-reality-based simulation using passive haptics has the potential to complement conventional training of knee arthroscopy skills. LEVEL OF EVIDENCE: II.

Lateral patellofemoral ligament reconstruction using a free gracilis autograft.

Medial patellofemoral instability is a rare, disabling condition that is often associated with the wrong indication for lateral retinacular release or overcorrection with medializing tibial tubercle osteotomy. It is an even less common complication after total knee arthroplasty (TKA). The lateral patellofemoral ligament is an important lateral stabilizer of the patella against medial subluxation or dislocation. Until now, no report in the literature has described lateral patellofemoral ligament reconstruction with a free gracilis tendon autograft. Furthermore, there has not been a single case report of lateral patellofemoral ligament reconstruction after TKA. The authors describe a novel technique for reconstruction of the lateral patellofemoral ligament in a symptomatic medial subluxated patella resulting from TKA and extended lateral release in a 62-year-old patient. The result 1 year postoperatively was deemed successful. Clinically, the patella was stable, with correct tracking, and radiologically the patella was correctly positioned. With a technique similar to that used for the medial patellofemoral ligament, the lateral patellofemoral ligament can be reconstructed with a gracilis tendon autograft to permit stabilization independent of resting scar tissue of the lateral retinaculum. This operation can be performed in a minimally invasive way, without opening the joint, therefore decreasing the risk of joint infection. The authors showed a successful clinical and radiologic outcome 1 year after lateral patellofemoral ligament reconstruction in a patient with medial patellar instability after TKA and lateral release.

End-stage extension of the knee and its influence on tibial tuberosity-trochlear groove distance (TTTG) in asymptomatic volunteers.

PURPOSE: Increased tibial tuberosity-trochlear groove distance (TTTG) is one potential correcting parameter in patients suffering from lateral patellar instability. It was hypothesized that end-stage extension of the knee might influence the TTTG distance on MR images. METHODS: Transverse T1-weighted MR images of the knee were acquired at full extension, 15° and 30° flexion of the knee in 30 asymptomatic volunteers. MRI parameters: slice thickness: 3 mm, matrix: 256 × 384, FOV: 150 × 150 mm. Two observers independently measured the TTTG at all positions. RESULTS: Mean TTTG for observer 1 was 15.1 ± 3.2 mm at full extension, 10.0 ± 3.5 mm at 15° flexion and 8.1 ± 3.4 mm at 30° flexion. Mean TTTG for observer 2: 14.8 ± 3.3 mm at full extension, 9.4 ± 3.0 mm at 15° flexion, 8.6 ± 3.4 mm at 30° flexion. Mean values were significantly different (p < 0.001) between full extension and 15° as well as 30° flexion for both observers. Mean values were significantly different (p < 0.001) between 15° and 30° for observer 1, but not for observer 2 (n.s.). Interobserver agreement was very good (intraclass correlation coefficient: 0.87-0.88; p < 0.001). CONCLUSIONS: The TTTG increases significantly at the end-stage extension of the knee. Therefore, the comparability of published TTTG values measured on radiographs, CT and MRI at various flexion/extension angles of the knee are limited.

Preliminary clinical report of flexible videoarthroscopy in diagnostic knee and hip arthroscopy.

INTRODUCTION: Compared to rigid arthroscopic optics, a flexible camera system offers theoretically significant advantages: It has the potential to adapt to the naturally curved surface of joints, to move within the joint without stress to the cartilage or capsule and thereby to reduce the number of portals needed. Former studies evaluated flexible fiberoptic systems which were insufficient regarding image resolution. This is the first report on a new flexible videoendoscope with the so called "chip-on-the-tip" technology used in human joints. METHODS: With a plasma sterilized 3.9 diameter flexible video endoscopy system (Visera ENF V, OLYMPUS) commonly used in diagnostic rhino-laryngoscopy, we performed preliminary testing in cadaveric knee joints. After successful feasibility testing we utilized the tool in two qualitative diagnostic knee and five hip arthroscopies in combination with conventional rigid 30° and 70° arthroscopes (STORZ). RESULTS: Qualitative evaluation showed superior visualisation of the posterior aspects of the knee joint as insertion of the posterior medial and lateral meniscal horn, tibial insertion of the posterior cruciate ligament and the posterolateral capsulo-ligamentous corner with acceptable image resolution and clarity compared to the rigid arthroscope. In the hip, it was possible to pass around the femoral neck, avoiding additional portals. There seemed to be virtually no risk for cartilage damage at all. Difficulties of the system were scope handling, navigation and orientation within the joint as well as potential damage to the tool itself. CONCLUSION: This is to our knowledge the first report on flexible videoarthroscopy. Some of the expectations were met, such as to reach virtually every corner the joint with minimal risk for the cartilage or other joint structures and with acceptable image quality. However, there are many significant disadvantages which question the routine use of such a videoendoscopic system with its present technical features.

Haemophilic knee arthropathy: long-term outcome after total knee replacement.

PURPOSE: The objective of this study was to evaluate the long-term outcome and prosthetic survival of primary total knee arthroplasty in haemophilic patients. It was hypothesized that the infection and revision rate are higher and the outcome inferior when compared with patients without haemophilia. METHODS: Between 1985 and 2004, forty-three consecutive primary total knee replacements were performed in thirty haemophilic patients. These patients' charts were reviewed retrospectively. Twenty-five patients (34 knees) were available for clinical and radiological follow-up. The outcome was assessed using the Knee Society score, WOMAC and Kaplan-Meier survivorship analysis. RESULTS: An haematogenous infection occurred in two patients. In three patients, component revision was needed: two because of an infection and one because of a mechanical failure. After a mean follow-up of 9.6 years (2-20), 94% of the patients rated their result as either excellent or good. At time of follow-up, the Knee Society Score averaged 73.3 points (range, 29-100) and showed a significant gain (p < 0.001) compared to preoperative. Flexion contracture could be reduced significantly (p < 0.001) from 18.1° preoperatively to 8.4° at follow-up, whereas flexion remained unchanged. When infection or any component replacement was set as endpoints, the 10 years prosthetic survival was 90 and 86%, respectively. CONCLUSION: Total knee arthroplasty in haemophilic patients is a reliable treatment that results in pain relief and functional improvement with a low risk of postoperative infection. However, neither the postoperative infection rate nor the functional result does reach the same level as in a population not affected by haemophilia. LEVEL OF EVIDENCE: IV.

Embossing of a screw thread and TCP granules enhances the fixation strength of compressed ACL grafts with interference screws.

PURPOSE: Fixation of soft tissue grafts with interference screws relies on the friction of the graft between the screw and the bone tunnel. The goal of this study was to precondition such grafts by mechanical compression in order to reduce anticipated and undesired viscoelastic adaptation of the graft to screw pressure. Further, the otherwise slippery graft surface was modified with impressed tricalcium phosphate granules (TCP) to improve friction and mechanical hold. METHODS: Fresh flexor digitorum tendons from young bovines were used to create bundles with a diameter of 8-9 mm and were divided into 10 groups to compare the pullout strength and bone damage in a variety of construct scenarios. Specifically, the effects of graft precompression to reduce preimplantation graft diameter were investigated. Further the effects of impressing TCP granules and/or a screw thread into the tendon surface during the compression process were studied. RESULTS: In sawbone tests, radial graft compression allowed for a smaller bone tunnel (7 mm), but resulted in a significantly lower pullout strength of 174 N (95% CI: 97, 250), compared with controls [315 N (204, 426)]. In contrast, TCP coated [402 N (243, 561)], screw embossed grafts [458 N (302, 614)], and the combination of TCP and embossing [409 N (274, 543)] achieved higher pullout strengths when compared to the standard technique. In porcine bone, untreated grafts using an 8 mm screw pulled out at 694 ± 93 N, significantly higher loads were required to pullout compressed grafts with or without TCP coating (870 ± 74 and 878 ± 131 N), yet fixed with a 7 mm screw. CONCLUSION: Modification of the tendon graft surface has a large influence on the biomechanical performance of interference screw fixation and results in less bone damage inflicted during insertion to a smaller tunnel diameter, while simultaneously achieving superior pullout strength.

Influence of test temperature on biomechanical properties of all-inside meniscal repair devices and inside-out meniscus sutures--evaluation of an isolated distraction loading, worst-case scenario.

BACKGROUND: Studies on the biomechanical properties of meniscus repairs are usually performed at room instead of body temperature. However, various all-inside meniscal repair devices include bioabsorbable materials, which are mechanically sensitive to higher environmental temperatures. Therefore, we hypothesize that current test standards may systematically lead to a false overestimation of their performance. METHODS: In 84 cadaveric bovine lateral menisci, an artificial vertical lesion was repaired with different all-inside meniscal repair devices (FasT-Fix, FasT-Fix AB, RapidLoc, Meniscus Arrow, Meniscus Screw) compared to a vertical inside-out Ethibond Excel 2.0 suture loop. Maximum load-to-failure, stiffness, and failure mode were tested in a uniaxial distraction loading at 20°C and 37°C. FINDINGS: Most of the tested implants were not susceptible to the higher environmental test temperature with respect to maximum load-to-failure, stiffness, and failure mode. Only the RapidLoc showed a significantly decreased stiffness (-28.1%) and a statistical trend to lower maximum load-to-failure (-20.6%) at 37°C compared to 20°C. INTERPRETATION: 20°C environmental temperature seems to be an acceptable test condition for the most meniscal repair devices. However, if the bioabsorbable part of the implant is the weakest link, body temperature may be considered for testing to prevent false overestimation of the biomechanical properties. For future biomechanical in vitro testing of meniscal repair devices, this study may provide novel insight into biomechanical test protocols for considering the environmental test temperature as an influencing factor of the biomechanical properties of especially bioabsorbable meniscal repair devices.

Clinical and radiological results 21 years following successful, isolated, open meniscal repair in stable knee joints.

The long-term results over 20 years following meniscal repair in stable knees have not been described yet. The objective was therefore to analyze the clinical and radiological outcomes of successful, isolated, open meniscal repairs with an intact ACL after a mean follow-up of 20.6 years (range, 16-25) retrospectively in 26 patients. Clinical evaluation included objective (Lysholm, IKDC, Tegner) and subjective scores. Standard radiological assessment according to Ahlbäck's osteoarthritis classification and weight-bearing full-leg radiography for alignment were performed. Eight patients were excluded due to a re-rupture of the meniscus. In the 18 remaining patients (12 male, 6 female), the mean Lysholm and IKDC score was 97.8 points (range, 85-100) and 93% (range, 77-100) at the most recent follow-up, respectively. The Tegner activity scale averaged 4.2 (range, 3-7). Subjectively, 13 patients rated their outcome excellent, 4 good, and 1 fair. The radiological evaluation demonstrated an average development of "+1" grade (range, 0-"+2") osteoarthritic changes versus preoperatively; however, the contralateral healthy knee also revealed comparable (on average "+1" grade) degenerative changes reflecting natural history. The alignment was not significantly different between the operated and the contralateral leg. Overall, isolated open meniscal repair in stableness has the potential of a successful surgery with good to excellent long-term results. The development of osteoarthritic changes within the femorotibial compartments is mild and comparable to contralateral and the alignment of the axis is preserved. Therefore, repair of a ruptured meniscus is recommended whenever possible, even in isolated meniscal tears. However, a re-rupture rate of approximately 30% in isolated meniscal tears has to be acknowledged, which still reflects the need for biological enhancement of meniscal healing.

Closing wedge patellar osteotomy in combination with trochleoplasty.

Sulcus-deepening trochleoplasty may result in a serious patellofemoral incongruence in cases where the patella also is highly dysplastic. In such cases, a closing wedge osteotomy of the patella may be considered. The technique was used in two patients (both female, 16 1/2 and 14 years old respectively) out of 85 trochleoplasties performed. At two years follow-up, both patients showed a stable patella with correct tracking. Both considered their functional result as excellent. Postoperative radiographs showed a normal sulcus angle (135 degrees and 132 degrees) with good congruence. Closing wedge patellar osteotomy, combined with sulcus-deepening trochleoplasty, can increase patellofemoral congruence with good clinical outcome.

Classification of trochlear dysplasia as predictor of clinical outcome after trochleoplasty.

PURPOSE: Sulcus-deepening trochleoplasty restores the trochlear groove in patients with patellofemoral instability and underlying trochlear dysplasia. There are types of dysplasia both with (B and D) and without (A and C) a supratrochlear spur. The aim of this study was to identify influencing factors for the clinical outcome following trochleoplasty. METHODS: Forty-four knees in 38 patients who underwent trochleoplasty for instability (type A in 9, B in 15, C in 9 and D in 11 knees) were assessed clinically with the Kujala score and radiologically with radiographs and MRI. The median follow-up was 4 (2-7.8) years. RESULTS: At follow-up, the median Kujala score had improved from 68 (29-84) to 90 (42-100) points (P < 0.001). Instability (P < 0.001) and pain (P = 0.027) decreased significantly, but in 3 knees, pain was worse postoperatively. Twenty-seven knees were ranked as excellent, 10 as good, 2 as fair and 5 as poor. Overall, dysplasia types B and D benefited more from surgery than types A and C. The postoperative MRI revealed no chondrolysis or subchondral necrosis, but deterioration of cartilage on the lateral trochlear facet was identified. CONCLUSION: Trochleoplasty is a useful and reliable surgical technique to improve patellofemoral instability in patients with a dysplastic trochlea. While improved stability is predictable, pain is less predictable and may even increase following surgery. The overall results were directly dependent on the type of the dysplasia, with a significantly better clinical outcome in type B and D. The clinical relevance of this study is that severe dysplasia can successfully be treated with trochleoplasty. LEVEL OF EVIDENCE: III.

Minimum ten year results of total hip arthroplasty with the acetabular reinforcement ring in avascular osteonecrosis.

Total hip arthroplasty (THA) still carries a higher failure rate in patients with avascular necrosis of the femoral head (AVN) than in a similar patient population with THA for other reasons. This is particularly true for the acetabular component. One of the major factors accounting for this is the compromised acetabular bone quality with structural defects subsequent to collapsing of the femoral head in high-grade AVN. In this study we implanted an acetabular reinforcement ring with hook (ARRH), which had been used successfully for other indications with acetabular bone stock deficiency, in 32 consecutive THA's in 29 patients with AVN. Five patients died during the observation period of causes unrelated to the surgery, one patient was lost to follow-up and one patient could not be followed up due to chronic illness, leaving 25 hips (23 patients) with a minimum follow-up of ten years (mean: 11.8; range: 10-15). The mean Merle d'Aubigne score increased significantly from 7.7 preoperatively to 16.6 postoperatively (p < 0.001). One revision was performed for aseptic stem loosening. Of the unrevised hips, one acetabular component was classified as definitively loose. The cumulative 12-year survivorship for THA with ARRH in AVN was 95.2% (confidence interval: 86.1-100%) for both components, 100% for the cup and 95.2% for the stem (86.1-100%).