Can knee position save blood following total knee replacement?

Previous research showed knee flexion at 70 degrees for 6 h following total knee replacements (TKR) reduced wound drainage by 30%. However, wound drainage may not represent total blood loss and obstruction of the drain in flexion or the relative elevation of the knee could have caused the reduction in drainage. We wished to confirm that this simple, cheap method not only reduced wound drainage but also total haemoglobin loss and determine what part elevation or drain obstruction may play. Sixty consecutive TKR patients were randomly allocated to three groups. Group 1-knee extended and level with bed. Group 2-leg elevated 35 degrees at the hip with knee flexed to 70 degrees for 6 h post-operatively. Group 3-leg elevated 35 degrees at the hip with knee extended for 6 h post-operatively. We assessed wound drainage over 48 h, calculated haemoglobin loss, total blood transfusion, pain, arc of motion, swelling, length of hospital stay and complications. We found knee flexion and knee elevation in extension reduced haemoglobin loss by 25%. Compromise to tissue oxygenation has been reported with knee flexion. We recommend elevation of the leg at 35 degrees from the hip with the knee extended. This offers a simple, safe and effective way to reduce total blood loss by 25%.     

How to quantify knee function after total knee arthroplasty?

Total knee arthroplasty (TKA) is being undertaken in a younger population than before and as a result the functional demands on the knee are likely to be increasing. As a consequence, it is important to define quantitative functional knee tests that can monitor any increase.A valuable functional knee test has to be able to distinguish small differences (selectivity) and has to be independent of pain (content validity). In this study, patient-based questionnaires (WOMAC and Knee Society score) and performance-based tests (sit-to-stand movement, maximal isometric contraction and timed-up-and-go) were used to assess which of these tests are selective and valid to measure knee function. Tests were considered to be selective if they could discriminate between knee patients and healthy control subjects, and to have functional content validity if they were relatively independent of pain. Twenty-eight patients were measured 16 months after surgery and compared to a healthy control group of 31 subjects.The sit-to-stand movement and timed-up-and-go test were both selective and functionally content valid. The timed-up-and-go test can be used for a quick initial assessment of global function and the sit-to-stand movement as a more biomechanical instrument identifying how the knee function of the patient is affected.     

Radiographic assessment of knee–ankle alignment after total knee arthroplasty for varus and valgus knee osteoarthritis

Background

There are unanswered questions about knee–ankle alignment after total knee arthroplasty (TKA) for varus and valgus osteoarthritis (OA) of the knee. The aim of this retrospective study was to assess knee–ankle alignment after TKA.

Does standing limb alignment after total knee arthroplasty predict dynamic alignment and knee loading during gait?

Background

A principle of TKA is to achieve a neutral standing coronal alignment of the limb (HKA angle) to reduce risks of implant loosening, reduce polyethylene wear, and optimize patellar tracking. Several long-term studies have questioned this because the relationship between alignment and implant survivorship is weaker than previously reported. We hypothesize that standing HKA poorly predicts implant failure because it does not predict dynamic HKA, dynamic adduction moment, and loading of the knee during gait. Therefore, the aim of our study is to assess the relationship between the standing and the dynamic (gait activity) HKAs.

Biomechanical effect of electromechanical knee–ankle–foot-orthosis on knee joint control in patients with poliomyelitis

In this study, an ideal electromechanical KAFO, satisfying stability in the stance and knee flexion in the swing phase during walking, was developed. Biomechanical evaluations were performed on four polio patients by means of three-dimensional gait analyses and energy consumption studies. From the three-dimensional gait analysis on poliomyelitis patients, a considerable amount of knee flexion during the swing phase was observed in controlled-knee gait, which resulted in approximately 33% less energy consumption than in locked-knee gait. The developed electromechanical KAFO in this study was helpful in poliomyelitis patients having partial or complete paralysis of the lower extremity, providing both stability in the stance and free swinging of the knee. This unit was efficient in the transfer of energy.     

When should we do knee replacements?

It is not known whether it is better to perform total knee replacements early or late in the course of arthritis. To examine the determinants of patient-related outcomes after knee replacement, we examined 812 patients in the Avon knee registry, in whom pre-operative and 5-year post-operative American Knee Society Scores were available. Ninety percent had a good outcome at 5 years. Women had significantly more severe disease at the time of surgery than men. Older people (>79 years) had the worst disease at the time of surgery, and made the least health gain, although their overall outcomes were still good. Those with the most severe disease at the time of operation made greater gains to those with less disease, but remained in worse health at 5 years, suggesting that earlier surgery may be preferable.     

Why are revision knee replacements failing?

AimThe number of knee revisions worldwide has been steadily increasing. While being complex and expensive operations, a high percentage of knee revisions fail early. This study was conducted to evaluate the causes of failure of revision knee replacements.Patients and methodsThis study retrospectively evaluated 95 patients following knee revision surgery and who underwent further knee revision operations. Indications for index revision as well as the reason for re-revision were recorded. Follow-up was from 30 to 97 months (mean 62 months).ResultsThe main cause of failure of revision knee replacements was infection (31 of 95, 32.6%) followed by aseptic loosening (30.5%). Indications for re-revision were instability in 12.6%, persistent stiffness in 10.5%, ongoing pain in 7.3%, extensor mechanism problems in 5.2%, and suspected metal allergy in one.ConclusionInfection and loosening continue to be the main reasons for failure of knee revisions. Improving outcomes for infection management and improved fixation methods may help reduce failed knee revisions.     

Does increasing step width alter knee biomechanics in medial compartment knee osteoarthritis patients during stair descent?

BackgroundResearch shows that one of the first complaints from knee osteoarthritis (OA) patients is difficulty in stair ambulation due to knee pain. Increased step width (SW) has been shown to reduce first and second peak internal knee abduction moments, a surrogate variable for medial compartment knee joint loading, during stair descent in healthy older adults. This study investigates the effects of increased step width (SW) on knee biomechanics and knee pain in medial compartment knee OA patients during stair descent.MethodsThirteen medial compartment knee OA patients were recruited for the study. A motion analysis system was used to obtain three-dimensional joint kinematics. An instrumented staircase was used to collect ground reaction forces (GRF). Participants performed stair descent trials at their self-selected speed using preferred, wide, and wider SW. Participants rated their knee pain levels after each SW condition.ResultsIncreased SW had no effect on peak knee abduction moments and knee pain. Patients reported low levels of knee pain during all stair descent trials. The 2nd peak knee adduction angle and frontal plane GRF at time of 2nd peak abduction moment were reduced with increasing SW.ConclusionsThe findings suggest that increases in SW may not influence knee loads in medial compartment knee OA patients afflicted with low levels of knee pain during stair descent.     

Does cruciate-retaining total knee arthroplasty enhance knee flexion in Western and East Asian patient populations? A meta-analysis

IntroductionThis study analyzed the published data to examine if CR TKAs can enhance the flexion and functional outcomes of the knee in the Western and East Asian populations using a meta-analysis approach.Materials and methodsA systematic review of literature published through Medline and EMBASE was conducted. The inclusion criteria were: primary TKA, follow up duration greater than one year, a fixed bearing CR prosthesis, and data for maximum pre- and post-operative flexion along with standard deviations or errors. We estimated the weighted mean differences between pre- and post-operative flexion, extension and knee scores (KSS and HSS) via a random effect model.ResultsSeventeen articles were selected and reviewed among 1229 studies that included 1090 knees of the Western and 516 knees of the East Asian. No significant difference was noted in maximal knee flexion pre- and post-operatively, when all the studies were pooled together (? 0.17°, p = 0.93, post-operative < pre-operative). The mean difference in flexion was ? 1.87° (p = 0.2) and 2.03° (p = 0.17), respectively in the both populations. However, the extension angle was significantly improved by ? 5.49° and ? 13.05° (p < 0.05), respectively. KSS scores were significantly improved by 46.39 and 51.63, and HSS scores by 36.65 and 30.67 (p < 0.05), respectively in the both populations.ConclusionThe meta-analysis indicated that contemporary CR TKAs have not been shown to enhance post-operative flexion capability in the Western and East Asian. The extension angles of the knee and the knee scores were significantly improved in both populations.     

Revision of medial Oxford unicompartmental knee replacement to a total knee replacement: Similar to a primary?

Unicompartmental knee replacement (UKR) is an option for the treatment of isolated medial compartment osteoarthritis. A commonly perceived potential advantage is that revision of a UKR is straightforward. The purpose of this study was to determine the early outcomes and the level of complexity of revisions of Oxford UKRs performed at our hospital. A retrospective review of a prospective database of all phase III Oxford UKRs was undertaken. This identified 89 Oxford UKRs which were revised at our institution between 2002 and 2008. The median time from the primary procedure to revision was 19 months (interquartile range 2-73 months). Nine were revised to another UKR. Eighty were revised to a total knee replacement (TKR). Fifty-three were revised with primary TKR components. Twenty-seven were revised using stems and/or augments. The median overall tibial component thickness (including augments) was 15 mm. Forty-five knees had an overall tibial component thickness greater than 15 mm. A primary Oxford UKR bearing thickness of greater than 6mm was associated with an increased likelihood of requiring revision components. On the basis of this review, tibial bone defects were commonly encountered when revising UKRs. Reconstruction with either an augment and a stem, or thick polyethylene component was often required. We recommend that the potential complexity of revision for UKR failure should be borne in mind when considering a primary Oxford UKR.     

Inter-rater reliability of the GNRB® knee arthrometer

BackgroundIn clinical settings, where arthrometers are mainly used by different clinicians, knowing the inter-rater reliability of the instrument is crucial in order for the results from different examiners to be accurately interpreted and limitations fully understood. The aim of this study was to evaluate the inter-rater reliability of the GNRB® knee arthrometer.MethodsKnee anterior laxity in both knees was tested in a group of young, uninjured subjects (N = 27, 13 females) by two examiners. Knee anterior laxity was calculated at test forces of 134 N and 250 N with values presented for the unstandardised and standardised conditions (relative to patellar stabilisation force).ResultsThe ICCs ranged from 0.220 to 0.424.ConclusionsThe inter-rater reliability of the GNRB® knee arthrometer is low.     

Fast-track knee arthroplasty – status and future challenges

BackgroundFast-track programs have been developed for different surgical procedures leading to higher patient satisfaction and lower morbidity. This concept has been extended to knee arthroplasty in recent years. The purpose of this narrative review was to discuss the different aspects of fast-track knee arthroplasty.MethodBoth authors searched the contemporary literature on minimally invasive knee arthroplasty and review articles on fast-track surgery aiming to summarize recent developments.ResultsLength of stay after knee arthroplasty is influenced by preoperative risk factors, anaesthetic and surgical techniques, pain, orthostatic intolerance, cognitive function, sleep disturbances, bleeding and anaemia and finally muscle function and rehabilitation.ConclusionsFast-track surgery reduces the length of stay and the morbidity after knee arthroplasty.Clinical relevanceOptimisation of pre-, per- and postoperative pathway for knee arthroplasty reduces morbidity after this type of surgery and results in shorter length of stay.     

Does mobile-bearing knee arthroplasty motion change with activity?

BackgroundThe purpose of this study was to evaluate the effect of mobile-bearing implant design and activity on knee arthroplasty kinematics during three activities of daily living.MethodsIn vivo kinematics were analyzed using 3D model registration from fluoroscopic images of non-weightbearing knee flexion-extension, weight-bearing squatting and stair activities in 20 knees in 10 patients with bilateral total knee arthroplasty. Each patient had one rotating-platform and one meniscal-bearing variant of the same prosthesis design.ResultsAnteroposterior translations in meniscal-bearing knees were larger than those in rotating-platform knees for the different dynamic conditions. Meniscal-bearing knees showed more posterior femoral locations with activities that increased demand on the quadriceps. Condylar translations changed little in rotating-platform knees with different activities.ConclusionsActivity dynamics can have a significant influence on knee kinematics, and have a greater effect on the kinematics of unconstrained meniscal-bearing prostheses than rotating-platform knee prostheses.Level of evidenceLevel II.     

Malignant transformation in synovial chondromatosis of the knee?

Although it has been reported, malignant transformation of synovial chondromatosis is rare. We report a case of malignant transformation of synovial chondromatosis in a knee to a low-grade chondrosarcoma, which was treated with synovial excision and total knee replacement. We also present a literature review of the subject. The case illustrates that malignant transformation should be suspected in chronic cases with a sudden exacerbation of symptoms and that interpretation of histology in cartilage lesions is difficult. It also demonstrates that even when guided biopsy techniques are used, the sampling error of a needle biopsy in any large lesion is unavoidable.     

Should the patella be resurfaced during total knee replacement?

Patellar resurfacing during total knee replacement (TKR) has been a controversial subject for many years. In 1990 a randomised prospective study was started to compare policies of resurfacing, not resurfacing and selectively resurfacing the patella. One hundred and twenty-five cases (suitable for a cruciate sparing TKR) were randomised. At the 5-year review, the group in which the patella had not been resurfaced had needed significantly more secondary surgery than the other groups. Global knee scoring systems showed little difference between the groups but a scoring system which focused on the patella revealed differences and demonstrated worse results when the patella was not resurfaced. A minor degree, of maltracking was tolerated in resurfaced knees but tended to cause pain and articular cartilage wear in unresurfaced patellae. Four knees with good patellar articular cartilage at surgery did poorly when not resurfaced, suggesting that a selective policy is not totally reliable. Routine patellar resurfacing gave the most reliable results.     

The fabella: a forgotten source of knee pain?

We present a case of chondromalacia of the fabella, describe a provocative diagnostic test and review the literature on this unusual cause of knee pain.     

Should the patella be resurfaced at total knee replacement?

Total knee replacement (TKR) presumably is replacement of the total knee articular surface. Sometimes it is and sometimes it is not. It is this author's firm conviction that the patella should be resurfaced in the vast majority of cases. Such advocacy must be critically justified and the potential drawbacks and alternatives examined.     

Is bilateral knee arthroscopy suitable as a day-case procedure?

A retrospective analysis of 100 out of 108 cases has been audited for suitability of bilateral knee arthroscopy as a day-case procedure. Fifty-three female and 47 male patients with age range of 15-78 years underwent bilateral knee arthroscopy. All patients had general anaesthetic and were ASA grade 1 or 2. Eight patients had more than one diagnosis and procedures. Post-operatively 68% could walk without walking aids, 1% had 1 stick and 31% needed 2 sticks and were given elbow crutches. One patient stayed overnight due to poor pain control and 1 attended A&E due to effusion. There were 5 (2.5%) major and 62 (31%) minor complications in 200 knees. Mild post-operative pain was the commonest minor complication in 52 (26%) out of 62 knees and was attributed to high number of bilateral arthritis cases in this study. Complication rate of bilateral arthroscopy is similar to unilateral arthroscopy. It is concluded that bilateral arthroscopy is safe as a day-case procedure.