Inclusion of water temperature in a fuzzy logic Atlantic salmon (Salmo salar) parr habitat model.

As water temperature is projected to increase in the next decades and its rise is clearly identified as a threat for cold water fish species, it is necessary to adapt and optimize the tools allowing to assess the quantity and quality of habitats with the inclusion of temperature. In this paper, a fuzzy logic habitat model was improved by adding water temperature as a key determinant of juvenile Atlantic salmon parr habitat quality. First, salmon experts were consulted to gather their knowledge of salmon parr habitat, then the model was validated with juvenile salmon electrofishing data collected on the Sainte-Marguerite, Matapedia and Petite-Cascapedia rivers (Québec, Canada). The model indicates that when thermal contrasts exist at a site, cooler temperature offered better quality of habitat. Our field data show that when offered the choice, salmon parr significantly preferred to avoid both cold areas (<15 °C) and warm areas (>20.5 °C). Because such thermal contrasts were not consistently present among the sites sampled, the model was only validated for less than 60% of the sites. The results nevertheless indicate a significant correlation between median Habitat Quality Index and parr density for the Sainte-Marguerite River (R2 = 0.38). A less important, albeit significant (F-test; p = 0.036) relationship was observed for the Petite-Cascapedia river (R2 = 0.14). In all instances, the four-variable (depth, velocity, substrate size and temperature) model provided a better explanation of parr density than a similar model excluding water temperature.

Erratum: New insights and new hope for pulmonary arterial hypertension: natriuretic peptides clearance receptor as a novel therapeutic target for a complex disease.

[This corrects the article on p. 112 in vol. 9, PMID: 28951773.].

Fibulocalcaneal Impingement in a Growing Child With Otherwise Asymptomatic Talocalcaneal Coalition.

Subfibular impingement has been described in patients with flatfoot. It possibly occurs with valgus deformity associated with talocalcaneal coalition. We observed symptomatic unilateral fibular impingement initially on the left foot of an 11-year-old female with an otherwise asymptomatic bilateral talocalcaneal coalition. From the age of 8 years, she had complained of pain around the left fibular tip. Magnetic resonance imaging showed a partial talocalcaneal coalition. At 10 years of age, it was questioned whether the pain was related to the coalition. However, imaging of the asymptomatic right foot also showed a talocalcaneal coalition, with the coalition in both feet appearing equal. Additionally, the peroneal trochlea appeared particularly prominent, more so on the left than on the right foot. Therefore, the symptoms were suspected to have been caused only by fibulocalcaneal impingement owing to a relatively long fibula. Subperiosteal shortening of the fibula was performed at when she was 11 years old. A bed for the peroneal tendons was created around the remaining epiphysis of the fibula, and the fibular ligaments were reattached with Arthrex® anchors (Arthrex, Naples, FL). At 14 months postoperatively, the patient was free of pain with unrestricted movement, although the follow-up imaging studies showed complete bony fusion on the medial aspect of the coalition between the talus and calcaneus. Approximately 1.5 years after surgery, our female patient at 12.5 years old complained of the same problems on her right foot, definitely occurring only around the fibula. The same procedure was performed as she had undergone on the left foot. At the last follow-up examination, she was asymptomatic 2.5 years after the initial surgery of the left foot and 11 months after surgery on the right. Talocalcaneal coalition can cause moderate to severe hindfoot deformity, leading to fibulocalcaneal impingement. Hence, treatment should be determined accordingly.

New insights and new hope for pulmonary arterial hypertension: natriuretic peptides clearance receptor as a novel therapeutic target for a complex disease.

BACKGROUND: Pulmonary Arterial Hypertension (PAH) is a deadly and disabling disease for which there is no marketed drug that addresses the underlying disease mechanism and targets to cure patients. The lack of understanding of the disease mechanism represents the main challenges in developing curative therapies. We here report, for the first time, that mice lacking natriuretic peptides clearance receptor develop PAH. METHODS AND RESULTS: Initial studies assessed cardiac structure and function in NPR-C+/+ (wild type) and age matched, littermate NPR-C-/- mice by echocardiography. Mice lacking NPR-C had right atrial dilation, tricuspid regurgitation as well as echocardiographic signs of right ventricular pressure overload, including flattening and paradoxical bulging of the septum into the left ventricle during systole, and hypertrophy of the right ventricular free wall. Among the 10 NPR-C-/- mice aged between 12 and 20 weeks studied, 8 showed the above typical echocardiographic features of PAH [80%, 95% CI: (0.4439-0.9748)], and only one had pericardial effusion [10%, 95% CI: (0.0025-0.4450)], finding that has a prognostic significance in subjects affected by this clinical entity. To confirm the presence of increased right ventricular systolic pressure (RVSP) among NPR-C-/- mice, right heart catheterization was performed. Strikingly, RVSP was significantly elevated in NPR-C-/- mice compared to their age matched, littermate NPR-C+/+ mice, at baseline (21.95±0.56 mmHg vs. 5.3±0.6 mmHg, respectively (P<0.001)). CONCLUSION: The above results suggest that NPR-C-mediated signalling pathways play a critical role in the development of PAH, indicating that NPR-C is an important protective receptor in the heart rather than just being a clearance receptor.

A natriuretic peptides clearance receptor's agonist reduces pulmonary artery pressures and enhances cardiac performance in preclinical models: New hope for patients with pulmonary hypertension due to left ventricular heart failure.

BACKGROUND: In patients with left ventricular heart failure (HF), the development of pulmonary hypertension (PH) is common and represents a strong predictor of death. Despite recent advances in the pathophysiological understanding there is as yet no prospect of cure of this deadly clinical entity and the majority of patients continue to progress to right ventricular failure and die. Furthermore, there is no single medical treatment currently approved for PH related to HF. There is, therefore an urgent unmet need to identify novel pharmacological agents that will prevent the progressive increased or reverse the elevated pulmonary arterial pressures while enhancing cardiac performance in HF. METHOD AND RESULTS: We here reported, for the first time, using a pressure-loop (P-V) conductance catheter system, that a specific natriuretic peptides clearance receptors' agonist, the ring-deleted atrial natriuretic peptide analogue, cANF4-23 (cANF) reduces pulmonary artery pressures. Strikingly, the administration of the cANF in these mice decreased the RVSP by 50% (n=5, F 25.687, DF 14, p<0.001) and heart rate (HR) by 11% (n=5, F 25.69, DF 14, p<0.001) as well as enhancing cardiac performance including left ventricular contractility in mice. Most strikingly, mice lacking NPR-C were much more susceptible to develop HF, indicating that NPR-C is a critical protective receptor in the heart. CONCLUSION: Natriuretic peptides clearance receptors' agonists may, therefore represent a novel and attractive therapeutic strategy for PH related to HF, and ultimately improves the life expectancy and quality for millions of people around the planet.

The Thrust Plate Hip Prosthesis: A Follow-Up of 15-20 Years With 102 Implants.

BACKGROUND: Between November 1992 and January 1999, a cohort of 102 thrust plate hip prostheses was implanted. METHODS: We now clinically and radiologically evaluate the remaining 73 prostheses with a mean follow-up of 17.2 years. RESULTS: The Harris Hip Score increased from 51.4 points preoperatively to 94.3 points at the time of this follow-up. No further changes in the radiologic findings occurred since the first follow-up, published in 2005, conducted 2-8 years after implantation. Within 15 to 20 years after primary implantation of the 102 prostheses, 6 aseptic loosenings occurred, which correspond to a cumulated survival rate of 94.7% at 17 and 91.8% at 18 years. CONCLUSION: Although the thrust plate hip prostheses is no longer marketed, the biomechanical behaviour of this unique, clinically successful prosthesis deserves attention.

Can exhaled nitric oxide differentiate causes of pulmonary fibrosis?

BACKGROUND: Interstitial lung diseases (ILD) comprise a heterogeneous group of disorders, and when diagnosed at the stage of pulmonary fibrosis, the underlying lung disease can sometimes be difficult to identify. The aim of the present study was to determine whether there are differences in FENO (fraction of exhaled nitric oxide) between different subtypes of fibrotic ILD. METHODS: Sixty-one patients, with honeycombing on computed tomography (CT) scan, and whose FENO levels had been measured during chronic dyspnoea evaluation, were divided into four groups based on pulmonary fibrosis aetiology: idiopathic pulmonary fibrosis (IPF), chronic hypersensitivity pneumonitis (HP), connective tissue disease-associated ILD disorders (CTD-ILD), drug-induced pneumonia. The FENO values of each group were compared and CT scan features were analysed to identify the mechanisms involved in FENO change. RESULTS: The median FENO value of patients with chronic HP was 51 ppb (IQR 36-74), higher than that of the other groups (22 ppb (IQR 17-30) in IPF, 19 ppb (IQR 17-21) in drug-induced pneumonia, and 25 ppb (IQR 17-37) for CTD-ILD; p = 0.008). At the cut-off value of 41 ppb, the optimal sensitivity and specificity to diagnose HP with FENO were respectively 76.9% and 85.4%. On CT scans, only extensive lobular areas with decreased attenuation, a recognized marker of bronchiolar disease, were associated with high FENO values (p = 0.0002). CONCLUSION: FENO could be a tool for differentiating chronic HP from other types of pulmonary fibrosis. The mechanism involved seems to be bronchiolar disease.

A statistical approach for the assessment and redesign of the Nile Delta drainage system water-quality-monitoring locations.

There are several deficiencies in the statistical approaches proposed in the literature for the assessment and redesign of surface water-quality-monitoring locations. These deficiencies vary from one approach to another, but generally include: (i) ignoring the attributes of the basin being monitored; (ii) handling multivariate water quality data sequentially rather than simultaneously; (iii) focusing mainly on locations to be discontinued; and (iv) ignoring the reconstitution of information at discontinued locations. In this paper, a methodology that overcomes these deficiencies is proposed. In the proposed methodology, the basin being monitored is divided into sub-basins, and a hybrid-cluster analysis is employed to identify groups of sub-basins with similar attributes. A stratified optimum sampling strategy is then employed to identify the optimum number of monitoring locations at each of the sub-basin groups. An aggregate information index is employed to identify the optimal combination of locations to be discontinued. The proposed approach is applied for the assessment and redesign of the Nile Delta drainage water quality monitoring locations in Egypt. Results indicate that the proposed methodology allows the identification of (i) the optimal combination of locations to be discontinued, (ii) the locations to be continuously measured and (iii) the sub-basins where monitoring locations should be added. To reconstitute information about the water quality variables at discontinued locations, regression, artificial neural network (ANN) and maintenance of variance extension (MOVE) techniques are employed. The MOVE record extension technique is shown to result in a better performance than regression or ANN for the estimation of information about water quality variables at discontinued locations.

The endlock tumor prosthesis with short-length fixation: a clinical study.

Anchorage of segmental replacement prostheses in diaphyseal bone remains a challenge in lower limb reconstructions. We developed and studied a new prosthesis design that features an intramedullary anchorage system for which finite element analysis predicted favorable bone remodeling. We retrospectively analyzed the cases of all patients who underwent implantation of the new stem. Their data were prospectively collected. Twenty-four patients (25 prosthetic reconstructions using diaphyseal fixation of the prosthesis) had 18 primary implantations and 7 revision cases. At a mean follow- up of 61 months, TESS (Toronto Extremity Salvage Score) and MSTS (Musculoskeletal Tumor Society Rating Scale score) were 80% and 65% that of a normal extremity, respectively. SF-36 (36-Item Short-Form Health Survey) Mental and Physical scores were 54 and 44 points, respectively. Minimum follow-up was 31 months (mean, 61 months; range, 31-107 months). Radiographic evaluation (1991 International Symposium of Limb Salvage [ISOLS] Radiological Implant Evaluation System) revealed 65% excellent and 35% good bone remodeling around the implant as a whole, 65% excellent and 35% good results for the anchorage proper, and 70% excellent and 30% good findings for lucencies at the bone-metal interface. Two patients (1 traumatic event) developed a loose stem. The results support the expectations as shown by finite element analysis - that the risk for loosening is reduced and that favorable bone remodeling occurs around the stem over time.

Evolution of open-wedge high-tibial osteotomy: experience with a special angular stable device for internal fixation without interposition material.

Surgical correction of bowed legs should be performed as early as possible. Overload osteoarthritis, even without significant varus deformity of the knee, is a further indication for open-wedge high-tibial osteotomy. Progression of damage to the joint surfaces due to overloading can be significantly retarded by realigning the extremity with the aim to, at least, reduce overload on the medial compartment to a value close to physiological. Significant improvement to open-wedge high-tibial osteotomy (OWHTO) has been made on two fronts: (a) by the use of a more appropriate surgical technique and (b) by promoting osteogenesis through an angular-stable fixation device with just the correct amount of elasticity. A retrospective study of 53 consecutive cases in which no interposition material was used to fill the wedge, with gap openings between 5 mm and 20 mm, showed that ossification of the gap always progressed from the lateral hinge towards the medial side. Standard radiographs showed 75% of the gap filled in with new bone within 6-18 months. In conclusion, we believe that open-wedge high-tibial osteotomy using the TomoFix plate has proved to be successful in treating unicompartmental gonarthrosis, even without bone grafts or bone-substitute material.

Changes in shoulder muscle function with humeral position: a graphical description.

A graphical description of the change in the role played by each of the scapulohumeral muscles with respect to spatial joint position is presented. Moment arms were collected from a biomechanical model using the tendon travel method. Data cover elevation and flexion in a space between the frontal plane and a plane of elevation 60 degrees anterior to this. Segments of a given muscle were seen possibly to exhibit antagonistic moment components in relation to others, emphasizing the importance of muscle segmentation in biomechanical models. Graphical description of muscle function in conjunction with electromyographic studies enables a more complete assessment of active muscle function in relation to arm motion and position. In cases of attenuated muscular function, this also offers a means of detecting which muscle is involved and which other muscles possess compensating potential. Two examples illustrate the use of this data, particularly to clarify clinical issues.

The contralateral foot in children with unilateral clubfoot: a study of pressures and forces involved in gait.

The unaffected contralateral side of patients with unilateral clubfeet has sometimes been taken as control in foot pressure measurement studies. However, it has never been shown that the pressure pattern under the contralateral foot is similar to a normal foot. Sixteen patients with unilateral clubfoot and 110 normal subjects took part in this study. All participants were aged from 4 to 8 years. Studies comprised clinical examination and foot pressure measurements in barefoot walking. Evaluations of the measurements were completed by the calculation of forces acting under 10 anatomical foot areas normalized to ground reaction force at foot-flat and push-off. Significant differences in peak pressure were observed between the control group and the contralateral foot of patients under the heel and the metatarsals 1 to 4. Significant differences in the forces at foot-flat and push-off are seen especially in the midfoot. Both sides of the patients with unilateral clubfeet exert significantly less ground reaction force than normal subjects. Different pressure and force distributions of clubfoot children on their contralateral side compared with the normal feet of the control group may indicate differences in the general control pattern generated by the central nervous system. Differences can still be observed after normalization of the forces. We therefore conclude that when foot pressure measurements are made with clubfeet, it might be advisable to use a collective of normal feet, instead of the contralateral foot, for comparison.

The biomechanical role of the subscapularis in latissimus dorsi transfer for the treatment of irreparable rotator cuff tears.

Inferior functional results of latissimus tendon transfer for the treatment of irreparable rotator cuff tears have been reported in the presence of a subscapularis tendon tear. A biomechanical or experimental explanation for the necessity of an intact subscapularis is unavailable. It was, therefore, the purpose of this investigation to study the biomechanical role of the subscapularis in the treatment of a posterosuperior rotator cuff tear with latissimus dorsi transfer. A biomechanical cadaveric model was developed to reproduce glenohumeral motion patterns created by loading of the transferred latissimus dorsi tendon with and without simultaneous action of the subscapularis muscle. Significant differences could be demonstrated not only for translation but also for rotation of the humeral head depending on subscapularis action. In the neutral and in the abducted/externally rotated position of the arm, anterior translation and dislocation of the joint were encountered without subscapularis action. Our results provide evidence that motion patterns of the humeral head are significantly altered in the absence of the stabilizing effect of the subscapularis muscle. The inferior functional results of latissimus dorsi transfer in the presence of subscapularis dysfunction are explained by the loss of centering of the humeral head upon abduction and elevation if subscapularis function is deficient.

Effects of glenoid component version on humeral head displacement and joint reaction forces: an experimental study.

The purpose of this study was to determine whether changes in glenoid version are associated with humeral head displacement and changes in the joint reaction forces, as these might contribute to instability or loosening in total shoulder replacement. A total shoulder prosthesis was implanted in neutral version in 6 cadaveric shoulders. Glenoid version was then changed in steps of 4 degrees toward more anteversion and retroversion. An increase in anteversion resulted in anterior translation of the humeral head and in eccentric loading of the anterior part of the glenoid. Retroversion was associated with posterior displacement and posterior loading of the glenoid. A change in rotation of the humeral component did not compensate for altered version of the glenoid component. These results suggest that both instability and glenoid component loosening may be related to the version of the glenoid component. Therefore, assessment of loosening and instability justifies precise assessment of glenoid component version.

Forces involved in lower limb lengthening: an in vivo biomechanical study.

Despite improvements in surgical techniques for limb-lengthening procedures, the complication rate remains high. Bone fixators must cope with the forces involved during treatment, providing sufficient strength to maintain integrity of the limb in the course of lengthening, while permitting some "micromotion" across the bone gap that could enhance healing during the final phase of bone consolidation. This study reports on the forces generated during limb lengthening in the distraction and consolidation phases. Forces were measured on 19 patients between 6 and 22 years of age with 10 femoral and 11 tibial lengthenings of 1 mm/day by means of a monotube external fixator, fitted diaphysially, and modified to measure tension and weight-bearing forces. Peak force measured during the lengthening period amounted to about 14 N/kg of body mass. Generally, distraction forces leveled off at between 8 and 10 N/kg of body mass. During the consolidation period, the average force carried by the fixator dropped from 55% initially to about 10% of the force transmitted to the ground, consistent with increased load carrying capacity of the bone as healing progressed. Studying the forces involved in limb lengthening is important to gain knowledge of the forces required to overcome the resistance offered by the tissues that bridge the osteotomy site, to understand the biology of distraction osteogenesis and histiogenesis across the regenerate over time, and to provide scientific guidelines for frame removal.

Moment arms of forearm rotators.

BACKGROUND: Rotation about a longitudinal axis of the forearm has been a matter of investigation for over 100 years. However, most studies were limited to only a few muscles and to their action in specific set positions of elbow and forearm rotation. This investigation aims at determining the moment arms of muscles that contribute to pronation and supination at three different angles of elbow flexion throughout the entire range of forearm rotation. METHODS: Muscle moment arms were derived from tendon excursions that were recorded on a full-size epoxy model of the radioulnar complex. The results were verified on a fresh cadaver specimen. FINDINGS: Moment arms of all major supinators exhibit peak values in 40-50 degrees of pronation, for all three positions of the elbow. These peak values vary with elbow position, the biceps muscle showing the highest dependency with its greatest moment arm in 90 degrees of elbow flexion. The pronators show a maximum of moment arm about the neutral position, with little dependency on elbow flexion. Brachioradialis brings the pronated, or supinated forearm into the neutral position. The bow of the radius is in function comparable to the 'throw' of a crankshaft, forming a greater lever arm between the point of insertion of the muscles and the axis of rotation of the radius. INTERPRETATION: The observations drawn from this study could be of eminent value in planning rotator muscle transplantation, in understanding functional disorders after injury, and in the physical treatment of forearm rotator muscle deficiency. Reconstruction of the physiological anatomical arrangement in the treatment of injuries is strongly recommended for restoration of function.

An algorithm for estimation of shoulder muscle forces for clinical use.

BACKGROUND: The shoulder joint represents an indeterminate mechanical system, making it difficult to predict individual muscle forces required to equilibrate a given arbitrary external force. Although considerable work has been published on this matter, no model exhibits the adaptability required for the analysis involving different positions of the humerus and for any external load. An algorithm involving decision-making loops is developed to predict forces exerted by muscles that cross the shoulder joint in equilibrating a given external force acting in an arbitrary direction, with the humerus in any one of 12 selected positions. METHODS: Muscle lever arms and directions of action collected from a full-size epoxy model of the shoulder joint are used together with the external force as input. The algorithm selects an appropriate group of muscles and step by step attributes small force increments to withstand the external moment while aiming at minimising the forces involved. Each muscle force increment is stored after every loop and eventually summed up. Stability of the glenohumeral joint is the final determining factor. FINDINGS: Six worked-out examples show interesting features of probable muscular activity. Muscle segmentation is of paramount importance for spatial control. Although stability can be achieved by increasing the overall rotator cuff activity (co-contraction), this is rarely necessary. INTERPRETATION: The strategy of force sharing among the muscles opens up the possibility to examine the outcome of muscle deficiencies and to investigate causes of joint instability as encountered in clinical practice. Further validation of the model is still needed, but certain clinical observations can be explained.

Radiological findings and clinical results of 102 thrust-plate femoral hip prostheses: a follow-up of 2 to 8 years.

We report the radiological and clinical outcome of 102 consecutive femoral hip arthroplasty we prospectively followed up in 84 patients using the third generation of the thrust-plate prosthesis with a mean period of follow-up of 58 (range, 26-100) months. Four implants were revised: 2 because of an infection and 2 because of aseptic loosening. The thrust-plate prosthesis, which allows preservation of part of the femoral neck, was used in younger patients, 80% were younger than 60 years. In 95 implants, contact was maintained between thrust plate and underlying bone, and in only 3 instances, without any clinical manifestation, did the bone retract from the thrust plate to the extent that a gap appeared. The extent of radiologically evident bone contact with the flat surface of the thrust plate, as a consequence of the bone remodeling behavior, is described and retrospectively classified. The average Harris hip score increased from 51 points preoperatively to 96 points postoperatively at the last follow-up. Survivorship analysis according to Kaplan-Meier showed a survival rate of 98% after 6 years, with no further losses up to the end of the 8-year follow-up period.

In vitro comparison of standard and Knotless metal suture anchors.

PURPOSE: Clinical experience after failed Knotless suture anchor (Mitek, Westwood, MA) fixations suggested that the Knotless anchor provides considerably less fixation stability than a standard metal anchor. The purpose of this study was to analyze soft tissue fixation to bone comparing a standard and a Knotless metal suture anchor. TYPE OF STUDY: In vitro study. METHODS: The Mitek GII and Mitek Knotless suture anchors were tested on 7 human cadaveric fresh-frozen glenoids. The anchors were inserted into the glenoid rims, and the sutures of the anchors were fixed to a metal hook attached to the cross-head of a testing machine. Cyclic loading was performed. The gap formation between the metal hook and the glenoid rim, the ultimate failure loads and the modes of failure were determined. RESULTS: The mean gap formation was significantly greater for the Knotless anchor (3.8 +/- 1.4 mm) than for the GII anchor (2.4 +/- 0.5 mm) after 25 cycles with 50 N repeated load (P =.04). The largest gap of a Knotless fixation was 5.3 mm compared with 3.0 mm for the GII. The ultimate failure load was not significantly different for the Knotless anchor (179 N) and for the GII anchor (129 N). Both anchors failed by either rupture of the suture material or by pullout of the anchors. CONCLUSIONS: The GII anchor allows significantly less displacement than the Knotless anchor. Ultimate tensile strength and mode of failure are similar. Greater displacement results in larger gap formation between the soft tissue and the bone. This might weaken and jeopardize the repair. CLINICAL RELEVANCE: If reattached soft tissues are subjected to postoperative loading, gap formation may result when using the Knotless anchor. For these conditions, suture fixation with knots may be used instead.

Coronoid process and radial head as posterolateral rotatory stabilizers of the elbow.

BACKGROUND: The purpose of this study was to evaluate the role of the radial head and the coronoid process as posterolateral rotatory stabilizers of the elbow and to determine the stabilizing effect of radial head replacement and coronoid reconstruction. METHODS: The posterolateral rotatory displacement of the ulna was measured after application of a valgus and supinating torque (1). in seven intact elbows, (2). after radial head excision, (3). after sequential resection of the coronoid process, (4). after subsequent insertion of each of two different types of metal radial head prostheses (a rigid implant and a bipolar implant with a floating cup), and (5). after subsequent reconstruction of the coronoid with each of two different techniques in the same cadaveric elbow. RESULTS: The posterolateral rotatory laxity averaged 5.4 degrees in the intact elbows. The surgical approach used in this study insignificantly increased the mean laxity to 9 degrees. Excision of the radial head in an elbow with intact collateral ligaments caused a mean posterolateral rotatory laxity of 18.6 degrees (p < 0.0001). Additional removal of 30% of the height of the coronoid fully destabilized the elbows, always resulting in ulnohumeral dislocation despite intact ligaments. Implantation of a rigid radial head prosthesis stabilized the elbows. However, a mean laxity of 16.9 degrees persisted after insertion of a floating prosthesis (p < 0.0001). The elbows with a defect of 50% or 70% of the coronoid, loss of the radial head, and intact ligaments could not be stabilized by radial head replacement alone, but additional coronoid reconstruction restored stability. CONCLUSIONS: The results of this study suggest that the coronoid and the radial head contribute significantly to posterolateral rotatory stability.