Investigating the autoregulation of applied blood flow restriction training pressures in healthy, physically active adults: an intervention study evaluating acute training responses and safety.

OBJECTIVE: To examine the effects of autoregulated (AUTO) and non-autoregulated (NAUTO) blood flow restriction (BFR) application on adverse effects, performance, cardiovascular and perceptual responses during resistance exercise. METHODS: Fifty-six healthy participants underwent AUTO and NAUTO BFR resistance exercise in a randomised crossover design using a training session with fixed amount of repetitions and a training session until volitional failure. Cardiovascular parameters, rate of perceived effort (RPE), rate of perceived discomfort (RPD) and number of repetitions were investigated after training, while the presence of delayed onset muscle soreness (DOMS) was verified 24 hours post-session. Adverse events during or following training were also monitored. RESULTS: AUTO outperformed NAUTO in the failure protocol (p<0.001), while AUTO scored significantly lower for DOMS 24 hours after exercise (p<0.001). Perceptions of effort and discomfort were significantly higher in NAUTO compared with AUTO in both fixed (RPE: p=0.014, RPD: p<0.001) and failure protocol (RPE: p=0.028, RPD: p<0.001). Sixteen adverse events (7.14%) were recorded, with a sevenfold incidence in the fixed protocol for NAUTO compared with AUTO (NAUTO: n=7 vs AUTO: n=1) and five (NAUTO) vs three (AUTO) adverse events in the failure protocol. No significant differences in cardiovascular parameters were found comparing both pressure applications. CONCLUSION: Autoregulation appears to enhance safety and performance in both fixed and failure BFR-training protocols. AUTO BFR training did not seem to affect cardiovascular stress differently, but was associated with lower DOMS, perceived effort and discomfort compared with NAUTO. TRIAL REGISTRATION NUMBER: NCT04996680.

The learning curve of imageless robot-assisted total knee arthroplasty with standardised laxity testing requires the completion of nine cases, but does not reach time neutrality compared to conventional surgery.

PURPOSE: The assistance of robot technology is introduced into the operating theatre to improve the precision of a total knee arthroplasty. However, as with all new technology, new technology requires a learning curve to reach adequate proficiency. The primary aim of this study was to identify the learning curve of an imageless robotic system with standardised laxity testing. The secondary aim of this study was to evaluate the accuracy of the intra-operative coronal alignment during the learning curve. METHODS: A prospective study was performed on 30 patients undergoing robot-assisted total knee arthroplasty with an imageless robotic system (Corin, Massachusetts, USA) associated with a dedicated standardised laxity testing device. The learning curve of all surgical steps was assessed with intra-operative video monitoring. As comparison, the total surgical time of the last 30 patients receiving conventional total knee arthroplasty by the same surgeon and with the same implant was retrospectively assessed. Coronal lower limb alignment was evaluated pre- and post-operatively on standing full-leg radiographs. RESULTS: CUSUM (cumulative summation) analysis has shown inflexion points in multiple steps associated with robot-assisted surgery between one and 16 cases, which indicates the progression from the learning phase to the proficiency phase. The inflexion point for total operative time occurred after nine cases. Robot-assisted total knee surgery required significantly longer operative times than the conventional counterpart, with an average increase of 22 min. Post-operative limb and implant alignment was not influenced by a learning curve. CONCLUSION: The introduction of an imageless robotic system with standardised laxity assessment for total knee arthroplasty results in a learning curve of nine cases based on operative time. Compared to conventional surgery, the surgeon is not able to reach time neutrality with the robotic platform. There is no learning curve associated with coronal limb or implant alignment. This study enables orthopaedic surgeons to understand the implementation of this surgical system and its specific workflow into clinical practice.

Muscle loaded stability reflects ligament-based stability in TKA: a cadaveric study.

PURPOSE: This paper aims at evaluating the effects of muscle load on knee kinematics and stability after TKA and second at evaluating the effect of TKA surgery on knee kinematics and stability; and third, at correlating the stability in passive conditions and the stability in active, muscle loaded conditions. METHODS: Fourteen fresh frozen cadaveric knee specimens were tested under passive and active condition with and without external loads involving a varus/valgus and internal/external rotational torque before and after TKA surgery using two in-house developed and previously validated test setups. RESULTS: Introduction of muscle force resulted in increased valgus (0.98°) and internal rotation of the femur (4.64°). TKA surgery also affected the neutral path kinematics, resulting in more varus (1.25°) and external rotation of the femur (5.22°). All laxities were significantly reduced by the introduction of the muscle load and after implantation of the TKA. The presence of the implant significantly affects the active varus/valgus laxity. This contrasts with the rotational laxity, in which case the passive laxity is the main determinant for the active laxity. For the varus/valgus laxity, the passive laxity is also a significant predictor of the active laxity. CONCLUSION: Knee stability is clearly affected by the presence of muscle load. This points to the relevance of appropriate rehabilitation with focus on avoiding muscular atrophy. At the same time, the functional, muscle loaded stability strongly relates to the passive, ligament-based stability. It remains therefore important to assess knee stability at the time of surgery, since the passive laxity is the only predictor for functional stability in the operating theatre. LEVEL OF EVIDENCE: Case series, Level IV.

The contralateral knee is a good predictor for determining normal knee stability: a cadaveric study.

PURPOSE: The goal is to evaluate contralateral knee joint laxity and ascertain whether or not contralateral symmetry is observable. Secondary, a validation of a knee laxity testing rig is provided. METHODS: Seven pairs of cadaveric knee specimens have been tested under passive conditions with and without external loads, involving a varus/valgus and an external/internal rotational torque and an anteroposterior shear force. RESULTS: Through the range of motion, the width of the varus/valgus laxity, internal/external laxity and anterior/posterior laxity for the medial and lateral compartment show no significant differences between left and right leg. These findings allow us to validate the setup, especially for relative values of laxity based on anatomical measures and knee joint biomechanics. CONCLUSION: A multidirectional laxity symmetry has been demonstrated for the intact knee and its contralateral knee in passive conditions as in an anesthetized patient. The passive laxity evaluation setup has been validated. Our work furthermore demonstrated a pronounced difference in anteroposterior mobility between the medial and lateral compartment of the knee, with a more stable medial side and more mobile lateral side. CLINICAL RELEVANCE: The contralateral knee can be used as reference for determining optimal knee laxity peri-operatively in total knee replacement and ligament reconstruction. LEVEL OF EVIDENCE: Level IV, Case series.

Prevention of venous thromboembolism with aspirin following knee surgery: A systematic review and meta-analysis.

Venous thromboembolism (VTE) is a well-known complication following orthopaedic surgery. The incidence of this complication has decreased substantially since the introduction of routine thromboprophylaxis. However, concerns have been raised about increased bleeding complications caused by aggressive thromboprophylaxis.Attention has grown for aspirin as a safer thromboprophylactic agent following orthopaedic surgery.A systematic review using MEDLINE, Embase and Web of Science databases was undertaken to compare the effectiveness of aspirin prophylaxis following knee surgery with the current standard prophylactic agents (low molecular weight heparin [LMWH], vitamin K antagonists and factor Xa inhibitors).No significant difference in effectiveness of VTE prevention was found between aspirin, LMWH and warfarin. Factor Xa inhibitors were more effective, but increased bleeding complications were reported.As evidence is limited and of low quality with substantial heterogeneity, further research with high-quality, adequately powered trials is needed. Cite this article: EFORT Open Rev 2021;6:892-904. DOI: 10.1302/2058-5241.6.200120.

Return to sport and work after medial open wedge high tibial osteotomy : a case series.

Data on return to work and sport following open wedge high tibial osteotomy (HTO) have been underreported. Furthermore, there is no clear consensus in literature about the postoperative alignment goals following HTO. A retrospective case series was performed to evaluate return to sport and work following open wedge HTO. The University of California, Los Angeles scale, the German classification system according to the Reichsausschuß für Arbeitszeitermittlung, the Tegner score and the Knee injury and Osteoarthritis Outcome Score were used to asses the employment status, sport status and clinical outcome at the time of surgery and at final follow-up, minimum 2 years after surgery. The pre- and postoperative hip knee ankle angle (HKA) were documented. The desired postoperative alignment target was 0°-2° valgus mechanical axis. 30 open wedge HTOs were performed of which 27 patients were retrospectively included in the study. 25 out of 26 patients returned to work and 15 out of 17 patients returned to sport following surgery. Outcome scores were significantly higher after surgery. The mean postoperative HKA was 0,9° of valgus mechanical axis. This study shows excellent outcome in sport and work activity and clinical outcome after open wedge HTO. We furthermore suggest that these outcomes can be obtained with a postoperative alignment of 0°-2° of valgus mechanical axis.

Biceps Femoris Compensates for Semitendinosus After Anterior Cruciate Ligament Reconstruction With a Hamstring Autograft: A Muscle Functional Magnetic Resonance Imaging Study in Male Soccer Players.

BACKGROUND: Rates of reinjury, return to play (RTP) at the preinjury level, and hamstring strain injuries in male soccer players after anterior cruciate ligament reconstruction (ACLR) remain unsatisfactory, due to multifactorial causes. Recent insights on intramuscular hamstring coordination revealed the semitendinosus (ST) to be of crucial importance for hamstring functioning, especially during heavy eccentric hamstring loading. Scientific evidence on the consequences of ST tendon harvest for ACLR is scarce and inconsistent. This study intended to investigate the repercussions of ST harvest for ACLR on hamstring muscle function. HYPOTHESIS: Harvest of the ST tendon for ACLR was expected to have a significant influence on hamstring muscle activation patterns during eccentric exercises, evaluated at RTP in a population of male soccer athletes. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 30 male soccer players with a history of ACLR who were cleared for RTP and 30 healthy controls were allocated to this study during the 2018-2019 soccer season. The influence of ACLR on hamstring muscle activation patterns was assessed by comparing the change in T2 relaxation times [ΔT2 (%) = post-exercise-T2pre-exerciseT2pre-exercise] of the hamstring muscle tissue before and after an eccentric hamstring loading task between athletes with and without a recent history of ACLR through use of muscle functional magnetic resonance imaging, induced by an eccentric hamstring loading task between scans. RESULTS: Significantly higher exercise-related activity was observed in the biceps femoris (BF) of athletes after ACLR compared with uninjured control athletes (13.92% vs 8.48%; P = .003), whereas the ST had significantly lower activity (19.97% vs 25.32%; P = .049). Significant differences were also established in a within-group comparison of the operated versus the contralateral leg in the ACLR group (operated vs nonoperated leg: 14.54% vs 11.63% for BF [P = .000], 17.31% vs 22.37% for ST [P = .000], and 15.64% vs 13.54% for semimembranosus [SM] [P = .014]). Neither the muscle activity of SM and gracilis muscles nor total posterior thigh muscle activity (sum of exercise-related ΔT2 of the BF, ST, and SM muscles) presented any differences in individuals who had undergone ACLR with an ST tendon autograft compared with healthy controls. CONCLUSION: These findings indicate that ACLR with a ST tendon autograft might notably influence the function of the hamstring muscles and, in particular, their hierarchic dimensions under fatiguing loading circumstances, with increases in relative BF activity contribution and decreases in relative ST activity after ACLR. This between-group difference in hamstring muscle activation pattern suggests that the BF partly compensates for deficient ST function in eccentric loading. These alterations might have implications for athletic performance and injury risk and should probably be considered in rehabilitation and hamstring injury prevention after ACLR with a ST tendon autograft.

Soft-tissue penetration of the oscillating saw during tibial resection in total knee arthroplasty.

AIMS: Inadvertent soft tissue damage caused by the oscillating saw during total knee arthroplasty (TKA) occurs when the sawblade passes beyond the bony boundaries into the soft tissue. The primary objective of this study is to assess the risk of inadvertent soft tissue damage during jig-based TKA by evaluating the excursion of the oscillating saw past the bony boundaries. The second objective is the investigation of the relation between this excursion and the surgeon's experience level. METHODS: A conventional jig-based TKA procedure with medial parapatellar approach was performed on 12 cadaveric knees by three experienced surgeons and three residents. During the proximal tibial resection, the motion of the oscillating saw with respect to the tibia was recorded. The distance of the outer point of this cutting portion to the edge of the bone was defined as the excursion of the oscillating saw. The excursion of the sawblade was evaluated in six zones containing the following structures: medial collateral ligament (MCL), posteromedial corner (PMC), iliotibial band (ITB), lateral collateral ligament (LCL), popliteus tendon (PopT), and neurovascular bundle (NVB). RESULTS: The mean 75th percentile value of the excursion of all cases was mean 2.8 mm (SD 2.9) for the MCL zone, mean 4.8 mm (SD 5.9) for the PMC zone, mean 3.4 mm (SD 2.0) for the ITB zone, mean 6.3 mm (SD 4.8) for the LCL zone, mean 4.9 mm (SD 5.7) for the PopT zone, and mean 6.1 mm (SD 3.9) for the NVB zone. Experienced surgeons had a significantly lower excursion than residents. CONCLUSION: This study showed that the oscillating saw significantly passes the edge of the bone during the tibial resection in TKA, even in experienced hands. While reported neurovascular complications in TKA are rare, direct injury to the capsule and stabilizing structures around the knee is a consequence of the use of a hand-held oscillating saw when making the tibial cut. Cite this article: Bone Joint J 2020;102-B(10):1324-1330.

How should we evaluate robotics in the operating theatre?

The application of robotics in the operating theatre for knee arthroplasty remains controversial. As with all new technology, the introduction of new systems might be associated with a learning curve. However, guidelines on how to assess the introduction of robotics in the operating theatre are lacking. This systematic review aims to evaluate the current evidence on the learning curve of robot-assisted knee arthroplasty. An extensive literature search of PubMed, Medline, Embase, Web of Science, and Cochrane Library was conducted. Randomized controlled trials, comparative studies, and cohort studies were included. Outcomes assessed included: time required for surgery, stress levels of the surgical team, complications in regard to surgical experience level or time needed for surgery, size prediction of preoperative templating, and alignment according to the number of knee arthroplasties performed. A total of 11 studies met the inclusion criteria. Most were of medium to low quality. The operating time of robot-assisted total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) is associated with a learning curve of between six to 20 cases and six to 36 cases respectively. Surgical team stress levels show a learning curve of seven cases in TKA and six cases for UKA. Experience with the robotic systems did not influence implant positioning, preoperative planning, and postoperative complications. Robot-assisted TKA and UKA is associated with a learning curve regarding operating time and surgical team stress levels. Future evaluation of robotics in the operating theatre should include detailed measurement of the various aspects of the total operating time, including total robotic time and time needed for preoperative planning. The prior experience of the surgical team should also be evaluated and reported. Cite this article: Bone Joint J 2020;102-B(4):407-413.

Efficacy of total knee arthroplasty (TKA) revision surgery depends upon the indication for revision : a systematic review.

The number of revision total knee arthroplasty (TKA) surgeries has increased over the years and it is expected that its number will keep rising. Most frequent reasons for revision are known to be aseptic loosening, infection, instability, periprosthetic frac- ture, arthrofibrosis and component malposition. The influence of the indication for revision on the outcome scores is not fully understood. Therefore, this work will evaluate and review the existing literature regarding outcome scores after revision TKA surgery. We conducted a sensitive and comprehensive search for published and unpublished studies relevant to the review question. We restricted our search to English studies published between January 2008 and December 2018. Our systematic review was done according to PRISMA guidelines. We withheld 19 studies (1419 knees) for inclusion. Of these, 9 papers reported outcome scores after TKA revision for aseptic loosening, 10 reported on revision for instability, 10 reported on stiffness or arthrofibrosis and 4 papers reported on component malposition. Although we found some papers suggesting that there is no difference in postoperative outcome scores depending on the aetiology of revision surgery, the majority of the included studies suggest differently. This review suggests there is a tendency for relative higher outcome scores after revision for aseptic loosening. Revision for malrotation might give comparable postoperative outcome scores and satisfaction ratios. Revision for instability tends to give lower postoperative outcome scores than aseptic loosening, although certain subgroups of instability show comparable results. Lowest postoperative scores might be found after revision for stiffness and arthrofibrosis.

Conservative treatment of knee osteoarthritis.

Osteoarthritis of the knee causes chronic knee pain, loss of function and disability in the ageing population. When no treatment is applied, a guaranteed onset of symptoms and/or structural damage can be observed in the diseased knee. This work reviewed the different published guidelines, proposing combinations of weight reduction, physical therapy and rehabilitation, self-management education programs and pharmacological treatment. Randomized clinical trials, systematic reviews and guidelines were identified using the databases PubMed and Web of Science. Specific journals and reference lists were investigated. Sixty high quality articles were included concerning the conservative treatment of knee osteoarthritis. Weight loss when BMI > 28kg/m 2 ; aerobic, proprioception and strengthening training; NSAIDs (ibuprofen, diclofenac, aceclofenac), IA corticosteroid and IA hyaluronic acid has the highest evidence. To achieve the greatest positive clinical and structural outcome, a combined conservative therapy is recommended.

Correction to: Surgeon experience with dynamic intraligamentary stabilization does not influence risk of failure.

The original version of this article unfortunately contains mistake in Table 4.

Surgeon experience with dynamic intraligamentary stabilization does not influence risk of failure.

PURPOSE: Studies on dynamic intraligamentary stabilization (DIS) of acute anterior cruciate ligament (ACL) ruptures reported failure rates similar to those of conventional ACL reconstruction. This study aimed to determine whether surgeon experience with DIS is associated with revision rates or patient-reported outcomes. The hypothesis was that more experienced surgeons achieved better outcomes following DIS due to substantial learning curve. METHODS: The authors prospectively enrolled 110 consecutive patients that underwent DIS and evaluated them at a minimum of 2 years. The effects of independent variables (surgeon experience, gender, age, adjuvant procedures, tear location, preinjury Tegner score, time from injury to surgery, and follow-up) on four principal outcomes (revision ACL surgery, any re-operation, IKDC and Lysholm score) were analyzed using univariable and multivariable regressions. RESULTS: From the 110 patients enrolled, 14 patients (13%) were lost to follow-up. Of the remaining 96 patients, 11 underwent revision ACL surgery, leaving 85 patients for clinical assessment at a mean of 2.2 ± 0.4 years (range 2.0-3.8). Arthroscopic reoperations were performed in 26 (27%) patients, including 11 (11%) revision ACL surgeries. Multivariable regressions revealed: (1) no associations between the reoperation rate and the independent variables, (2) better IKDC scores for 'designer surgeons' (b = 10.7; CI 4.9-16.5; p < 0.001), higher preinjury Tegner scores (b = 2.5, CI 0.8-4.2; p = 0.005), and younger patients (b = 0.3, CI 0.0-0.6; p = 0.039), and (3) better Lysholm scores for 'designer surgeons' (b = 7.8, CI 2.8-12.8; p = 0.005) and preinjury Tegner score (b = 1.9, CI 0.5-3.4; p = 0.010). CONCLUSION: Surgeon experience with DIS was not associated with rates of revision ACL surgery or general re-operations. Future, larger-scaled studies are needed to confirm these findings. Patients operated by 'designer surgeons' had slightly better IKDC and Lysholm scores, which could be due to better patient selection and/or positively biased attitudes of both surgeons and patients. LEVEL OF EVIDENCE: Level II, prospective comparative study.

How does lower leg alignment differ between soccer players, other athletes, and non-athletic controls?

PURPOSE: The influence of type and intensity of sports during growth on knee alignment was investigated. The second aim was to ascertain whether the distal femur or proximal tibia contribute most to knee alignment. Also, the influence of field position and leg dominancy on knee alignment in soccer players was audited. METHODS: Standardized full-leg standing digital radiographs were obtained from 100 males and 100 females on which 8 different alignment parameters were measured. Participants were questioned on their sports activities during different stages of growth. Sports activities were graded according to the Tegner score. RESULTS: The mean (±SD) hip-knee-ankle angle (HKA) was significantly lower (p < 0.001) in high-activity male athletes (-2.8° ± 2.4°) than in low-activity male athletes (-0.9° ± 1.9°). No differences in HKA were observed between different activity levels in females. Males who practiced soccer between 10-12 years and 15-17 years had, in turn, a lower HKA than athletes practicing other high-activity sports in these age categories (mean difference ≥1.2°, p ≤ 0.046). The most contributing factor for the varus alignment in male soccer players was a lower medial proximal tibial angle (MPTA). CONCLUSION: High-activity sports participation during youth is associated with varus alignment at the end of growth in males. The most pronounced bowlegs were observed in male soccer players, and this was primarily determined by the proximal tibia. Adjustments in loads applied to the knees during skeletal growth in males might prevent the development of varus alignment and associated pathology, but further studies are required. LEVEL OF EVIDENCE: Diagnostic study, Level III.

A New Prediction Model for Patient Satisfaction After Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is a proven and cost-effective treatment for osteoarthritis. Despite the good to excellent long-term results, some patients remain dissatisfied. Our study aimed at establishing a predictive model to aid patient selection and decision-making in TKA. METHODS: Using data from our prospective arthroplasty outcome database, 113 patients were included. Preoperatively and postoperatively, the patients completed 107 questions in 5 questionnaires: Knee Injury and Osteoarthritis Outcome Score, Oxford Knee Score, Pain Catastrophizing Scale, Euroqol questionnaire, and Knee Scoring System. First, outcome parameters were compared between the satisfied and dissatisfied group. Second, we developed a new prediction tool using regression analysis. Each outcome score was analyzed with simple regression. Subsequently, the predictive weight of individual questions was evaluated applying multiple linear regression. Finally, 10 questions were retained to construct a new prediction tool. RESULTS: Overall satisfaction rate in this study was found to be 88%. We identified a significant difference between the satisfied and dissatisfied group when looking at the preoperative questionnaires. Dissatisfied patients had more preoperative symptoms (such as stiffness), less pain, and a lower quality of life. They were more likely to ruminate and had a lower preoperative Knee Scoring System satisfaction score. The developed prediction tool consists of 10 simple but robust questions. Sensitivity was 97% with a positive-predictive value of 93%. CONCLUSIONS: Based upon preoperative parameters, we were able to partially predict satisfaction and dissatisfaction after TKA. After further validation, this new prediction tool for patient satisfaction following TKA may allow surgeons and patients to evaluate the risks and benefits of surgery on an individual basis and help in patient selection.

3D printed guides for controlled alignment in biomechanics tests.

The bone-machine interface is a vital first step for biomechanical testing. It remains challenging to restore the original alignment of the specimen with respect to the test setup. To overcome this issue, we developed a methodology based on virtual planning and 3D printing. In this paper, the methodology is outlined and a proof of concept is presented based on a series of cadaveric tests performed on our knee simulator. The tests described in this paper reached an accuracy within 3-4° and 3-4mm with respect to the virtual planning. It is however the authors' belief that the method has the potential to achieve an accuracy within one degree and one millimeter. Therefore, this approach can aid in reducing the imprecisions in biomechanical tests (e.g. knee simulator tests for evaluating knee kinematics) and improve the consistency of the bone-machine interface.

Patient-specific guides do not improve accuracy in total knee arthroplasty: a prospective randomized controlled trial.

BACKGROUND: Recently, patient-specific guides (PSGs) have been introduced, claiming a significant improvement in accuracy and reproducibility of component positioning in TKA. Despite intensive marketing by the manufacturers, this claim has not yet been confirmed in a controlled prospective trial. QUESTIONS/PURPOSES: We (1) compared three-planar component alignment and overall coronal mechanical alignment between PSG and conventional instrumentation and (2) logged the need for applying changes in the suggested position of the PSG. METHODS: In this randomized controlled trial, we enrolled 128 patients. In the PSG cohort, surgical navigation was used as an intraoperative control. When the suggested cut deviated more than 3° from target, the use of PSG was abandoned and marked as an outlier. When cranial-caudal position or size was adapted, the PSG was marked as modified. All patients underwent long-leg standing radiography and CT scan. Deviation of more than 3° from the target in any plane was defined as an outlier. RESULTS: The PSG and conventional cohorts showed similar numbers of outliers in overall coronal alignment (25% versus 28%; p = 0.69), femoral coronal alignment (7% versus 14%) (p = 0.24), and femoral axial alignment (23% versus 17%; p = 0.50). There were more outliers in tibial coronal (15% versus 3%; p = 0.03) and sagittal 21% versus 3%; p = 0.002) alignment in the PSG group than in the conventional group. PSGs were abandoned in 14 patients (22%) and modified in 18 (28%). CONCLUSIONS: PSGs do not improve accuracy in TKA and, in our experience, were somewhat impractical in that the procedure needed to be either modified or abandoned with some frequency.

Total knee arthroplasty at 15-17 years: does implant design affect outcome?

PURPOSE: A study was conducted to compare minimum 15-year survivorship and outcome of the Genesis I and II implants for total knee arthroplasty (TKA). METHODS: We retrospectively reviewed 245 consecutive TKA implanted between January 1995 and October 1997. Genesis I was implanted in 156 knees and Genesis II in 89 knees. RESULTS: At 15-17 years, 75 patients (31%) had died, 28 patients (11%) were lost to follow-up and 11 TKA were revised (4.6%), including ten Genesis I (6.4%) and one Genesis II (1.1%); 131 TKA (53%) were available for follow-up. Cumulative survivorship was 92.4% at 15.7 years. Survival in patients <69 years at surgery was lower (88.0%) compared with patients ≥69 years (98.5%; p = 0.023). In patients <69 years, Genesis I survival (84.3%) was worse compared with Genesis II (97.1%) (p = 0.018). Polyethylene (PE) Insert thickness ≤11 mm had significantly better survivorship (97.1%) compared with PE >11 mm (56.7%) (p < 0.0001) CONCLUSIONS: At a minimum of 15 years, the overall (92.4%) survivorship of Genesis TKA was good, with excellent (98.1%) survivorship of the Genesis II design. Revision rates were higher with Genesis I in the younger age group and with insert thickness >11 mm, possibly due to longer shelf life of less frequently used sizes.

The influence of freezing on the tensile strength of tendon grafts : a biomechanical study.

We investigated the influence of freezing on the tensile strength of fresh frozen tendon grafts. The biomechanical characteristics of tendons that are less commonly used in knee surgery (tibialis anterior, tibialis posterior, peroneus longus and medial and lateral half of Achilles tendons) were compared to those of a semitendinosus and gracilis graft harvested from the same 10 multi-organ donors. All right side tendons constituted the study group and were frozen at -80 degrees C and thawed at room temperature 5 times. All left side tendons were frozen at -80 degrees C and thawed at room temperature once. There were 59 tendons in the control group and 56 in the study group. The looped grafts were clamped at one side using a custom-made freeze clamp and loaded until failure on an Instron 4505 testing machine. The average ultimate failure load was not significantly different between the control and the study group (p > 0.05). The failure load of the medial tendon Achilles was the lowest in both study and control group (p < 0.001). There was no significant difference in maximum stress, maximum displacement, maximum strain and stiffness between the control and study group (p > 0.05). From our study, we conclude that freezing tendons at -80 degrees C and thawing several times does not influence the maximum load, maximum stress, maximum displacement, maximum strain and stiffness. The medial half of the Achilles tendon is clearly the weakest tendon (p < 0.001). These findings show that tendon grafts can be frozen at -80 degrees C and thawed at room temperature several times without altering their biomechanical properties.

Complex total knee arthroplasty using resection prostheses at mid-term follow-up.

Complex primary or revision TKA may require the use of a resection type prosthesis to address major bone loss and soft tissue deficiencies. The aim of this retrospective study is to evaluate the clinical and radiographic outcomes of salvage knee reconstructions in a larger cohort and longer follow-up than previously reported. We therefore present the results of 66 cases treated with the Finn/OSS knee system with an average follow-up of 5 years (range 2-12). Indications included 63 revision cases and three primary interventions with either massive bone loss and/or soft tissue deficiency. At final follow-up the average knee society score had significantly improved from 46 preoperatively to 73, and the function score improved from 27 to 47 points. Four cases needed to be revised: one for recurrent infection, two for aseptic loosening and one for implant breakage. Nine patients underwent minor reinterventions; including five cases with irrigation and debridement for prolonged wound drainage, two patellar realignment procedures and two extensor mechanism repairs. Two patients developed a peroneal nerve palsy. Overall implant survivorship with revision as the endpoint was 92% at 5 and 10 years. We conclude that the use of a resection prosthesis in the complex primary and revision TKA leads to acceptable results, but the complication rate is relatively high.