Aims. This study identifies early risk factors for symptomatic nonunion of displaced midshaft fractures of the clavicle that aid identification of an at risk group who may benefit from surgery. . Methods . We performed a retrospective study of 88 patients aged between 16 and 60 years that were managed non-operatively. . Results . The rate of symptomatic nonunion requiring surgery was 14% (n = 13). Smoking (odds ratio (OR) 40.76, 95% confidence intervals (CI) 1.38 to 120.30) and the six week Disabilities of the Arm Shoulder and Hand (DASH) score (OR 1.11, 95% CI 1.01 to 1.22, for each point increase) were independent predictors of nonunion. A six week DASH score of 35 or more was identified as a threshold value to predict nonunion using receiver operating characteristic curve analysis. Smoking and the threshold value in the DASH and were additive risk factors for nonunion, when neither were present the risk of nonunion was 2%, if one or the other were present the nonunion rate was between 17% to 20%, and if both were present the rate increased to 44%. Discussion. Patients with either of these risk factors, which include approximately half of all patients sustaining displaced midshaft fractures of the clavicle, are at an increased risk of developing a symptomatic non-union. Take home message: Smoking and failure of functional return at six weeks are significant predictors of nonunion of the midshaft of the clavicle. Such patients warrant further investigation as to whether they would benefit from early surgical fixation in order to avoid the morbidity of a nonunion. Cite this article: Bone Joint J 2016;98-B:125–30

Aims. The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods. A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results. Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion. Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process. Cite this article: Bone Joint J 2023;105-B(9):1020–1029

Several studies have reported the rate of post-operative mortality after the surgical treatment of a fracture of the hip, but few data are available regarding the delayed morbidity. In this prospective study, we identified 568 patients who underwent surgery for a fracture of the hip and who were followed for one year. Multivariate analysis was carried out to identify possible predictors of mortality and morbidity. The 30-day, four-month and one-year rates of mortality were 4.3%, 11.4%, and 18.8%, respectively. General complications and pre-operative comorbidities represented the basic predictors of mortality at any time interval (p < 0.01). In-hospital, four-month and one-year general complications occurred in 29.4%, 18.6% and 6.7% of patients, respectively. After adjusting for confounding variables, comorbidities and poor cognitive status determined the likelihood of early and delayed general complications, respectively (p < 0.001). Operative delay was the main predictor of the length of hospital stay (p < 0.001) and was directly related to in-hospital (p = 0.017) and four-month complications (p = 0.008). Cite this article: Bone Joint J 2015;97-B:383–90

Aims. We assessed the value of the Clinical Frailty Scale (CFS) in the prediction of adverse outcome after hip fracture. Methods. Of 1,577 consecutive patients aged > 65 years with a fragility hip fracture admitted to one institution, for whom there were complete data, 1,255 (72%) were studied. Clinicians assigned CFS scores on admission. Audit personnel routinely prospectively completed the Standardised Audit of Hip Fracture in Europe form, including the following outcomes: 30-day survival; in-hospital complications; length of acute hospital stay; and new institutionalization. The relationship between the CFS scores and outcomes was examined graphically and the visual interpretations were tested statistically. The predictive values of the CFS and Nottingham Hip Fracture Score (NHFS) to predict 30-day mortality were compared using receiver operating characteristic area under the curve (AUC) analysis. Results. Significant non-linear associations between CFS and outcomes were observed. Risk of death within 30 days rose linearly for CFS 1 to 5, but plateaued for CFS > 5. The incidence of complications and length of stay rose linearly for CFS 1 to 4, but plateaued for CFS > 4. In contrast, the risk of new institutionalization rose linearly for CFS 1 to 8. The AUCs for 30-day mortality for the CFS and NHFS were very similar: CFS AUC 0.63 (95% CI 0.57 to 0.69) and NHFS AUC 0.63 (95% CI 0.57 to 0.69). Conclusion. Use of the CFS may provide useful information on outcomes for fitter patients presenting with hip fracture, but completion of the CFS by the admitting orthopaedic team does not appear successful in distinguishing between higher CFS categories, which define patients with frailty. This makes a strong case for the role of the orthogeriatrician in the early assessment of these patients. Further work is needed to understand why patients assessed as being of mild, moderate, and severe frailty do not result in different outcomes. Cite this article: Bone Joint J 2022;104-B(8):980–986

Aims. Open fractures of the tibia are a heterogeneous group of injuries that can present a number of challenges to the treating surgeon. Consequently, few surgeons can reliably advise patients and relatives about the expected outcomes. The aim of this study was to determine whether these outcomes are predictable by using the Ganga Hospital Score (GHS). This has been shown to be a useful method of scoring open injuries to inform wound management and decide between limb salvage and amputation. Methods. We collected data on 182 consecutive patients with a type II, IIIA, or IIIB open fracture of the tibia who presented to our hospital between July and December 2016. For the purposes of the study, the patients were jointly treated by experienced consultant orthopaedic and plastic surgeons who determined the type of treatment. Separately, the study team (SP, HS, AD, JD) independently calculated the GHS and prospectively collected data on six outcomes for each patient. These included time to bony union, number of admissions, length of hospital stay, total length of treatment, final functional score, and number of operations. Spearman’s correlation was used to compare GHS with each outcome. Forward stepwise linear regression was used to generate predictive models based on components of the GHS. Five-fold cross-validation was used to prevent models from over-fitting. Results. The mean follow-up was 11.4 months (3 to 31). The mean time to union was 9.7 months (3 to 21), the mean number of operations was 2.8 (1 to 11), the mean time in hospital was 17.7 days (5 to 84), the mean length of treatment was 92.7 days (5 to 730), the mean number of admissions was 1.7 (1 to 6), and the mean functional score (Lower Extremity Functional Score (LEFS)) was 60.13 (33 to 80). There was a significant correlation between the GHS and each of the outcome measures. A predictive model was generated from which the GHS could be used to predict the various outcome measures. Conclusion. The GHS can be used to predict the outcome of patients who present with an open fracture of the tibia. Our model generates a numerical value for each outcome measure that can be used in clinical practice to inform the treating team and to advise patients. Cite this article: Bone Joint J 2020;102-B(1):26–32

Aims. The primary aim of this study was to develop a reliable, effective radiological score to assess the healing of humeral shaft fractures, the Radiographic Union Score for HUmeral fractures (RUSHU). The secondary aim was to assess whether the six-week RUSHU was predictive of nonunion at six months after the injury. Patients and Methods. Initially, 20 patients with radiographs six weeks following a humeral shaft fracture were selected at random from a trauma database and scored by three observers, based on the Radiographic Union Scale for Tibial fractures system. After refinement of the RUSHU criteria, a second group of 60 patients with radiographs six weeks after injury, 40 with fractures that united and 20 with fractures that developed nonunion, were scored by two blinded observers. Results. After refinement, the interobserver intraclass correlation coefficient (ICC) was 0.79 (95% confidence interval (CI) 0.67 to 0.87), indicating substantial agreement. At six weeks after injury, patients whose fractures united had a significantly higher median score than those who developed nonunion (10 vs 7; p < 0.001). A receiver operating characteristic curve determined that a RUSHU cut-off of < 8 was predictive of nonunion (area under the curve = 0.84, 95% CI 0.74 to 0.94). The sensitivity was 75% and specificity 80% with a positive predictive value (PPV) of 65% and a negative predictive value of 86%. Patients with a RUSHU < 8 (n = 23) were more likely to develop nonunion than those with a RUSHU ≥ 8 (n = 37, odds ratio 12.0, 95% CI 3.4 to 42.9). Based on a PPV of 65%, if all patients with a RUSHU < 8 underwent fixation, the number of procedures needed to avoid one nonunion would be 1.5. Conclusion. The RUSHU is reliable and effective in identifying patients at risk of nonunion of a humeral shaft fracture at six weeks after injury. This tool requires external validation but could potentially reduce the morbidity associated with delayed treatment of an established nonunion. Cite this article: Bone Joint J 2019;101-B:1300–1306

Aims. To identify the prevalence of neuropathic pain after lower limb fracture surgery, assess associations with pain severity, quality of life and disability, and determine baseline predictors of chronic neuropathic pain at three and at six months post-injury. Methods. Secondary analysis of a UK multicentre randomized controlled trial (Wound Healing in Surgery for Trauma; WHiST) dataset including adults aged 16 years or over following surgery for lower limb major trauma. The trial recruited 1,547 participants from 24 trauma centres. Neuropathic pain was measured at three and six months using the Doleur Neuropathique Questionnaire (DN4); 701 participants provided a DN4 score at three months and 781 at six months. Overall, 933 participants provided DN4 for at least one time point. Physical disability (Disability Rating Index (DRI) 0 to 100) and health-related quality-of-life (EuroQol five-dimension five-level; EQ-5D-5L) were measured. Candidate predictors of neuropathic pain included sex, age, BMI, injury mechanism, concurrent injury, diabetes, smoking, alcohol, analgaesia use pre-injury, index surgery location, fixation type, Injury Severity Score, open injury, and wound care. Results. The median age of the participants was 51 years (interquartile range 35 to 64). At three and six months post-injury respectively, 32% (222/702) and 30% (234/787) had neuropathic pain, 56% (396/702) and 53% (413/787) had chronic pain without neuropathic characteristics, and the remainder were pain-free. Pain severity was higher among those with neuropathic pain. Linear regression analyses found that those with neuropathic pain at six months post-injury had more physical disability (DRI adjusted mean difference 11.49 (95% confidence interval (CI) 7.84 to 15.14; p < 0.001) and poorer quality of life (EQ-5D utility -0.15 (95% CI -0.19 to -0.11); p < 0.001) compared to those without neuropathic characteristics. Logistic regression identified that prognostic factors of younger age, current smoker, below knee fracture, concurrent injuries, and regular analgaesia pre-injury were associated with higher odds of post-injury neuropathic pain. Conclusion. Pain with neuropathic characteristics is common after lower limb fracture surgery and persists to six months post-injury. Persistent neuropathic pain is associated with substantially poorer recovery. Further attention to identify neuropathic pain post-lower limb injury, predicting patients at risk, and targeting interventions, is indicated. Cite this article: Bone Joint J 2021;103-B(6):1047–1054

Aims. The aim of this study was to assess whether it is possible to predict the mortality, and the extent and time of neurological recovery from the time of the onset of symptoms and MRI grade, in patients with the cerebral fat embolism syndrome (CFES). This has not previously been investigated. Methods. The study included 34 patients who were diagnosed with CFES following trauma between 2012 and 2018. The clinical diagnosis was confirmed and the severity graded by MRI. We investigated the rate of mortality, the time and extent of neurological recovery, the time between the injury and the onset of symptoms, the clinical severity of the condition, and the MRI grade. All patients were male with a mean age of 29.7 years (18 to 70). The mean follow-up was 4.15 years (2 to 8), with neurological recovery being assessed by the Glasgow Outcome Scale and the Mini-Mental State Examination. Results. In all, seven who had early-onset CFES (< 24 hours), and a severe Takahashi grade on MRI, died. There was a significant association between the time of onset of neurological signs and mortality (p = 0.035). Mortality was also significantly associated with a severe Takahashi grade (p < 0.001). Among the 27 surviving patients, 26 (96.3%) recovered completely. One (3.7%) had a cognitive deficit. The mean time to recovery was 4.7 weeks (2 to 13), with late recovery aftereight eight weeks being recorded in three patients. Conclusion. There was a significantly increased rate of mortality in patients with CFES who had an early onset of symptoms and a severe grade on MRI. Complete neurological recovery can be expected in most patients with CFES who survive. Cite this article: Bone Joint J 2022;104-B(1):142–149

Aims

The aims of this study were to identify means to quantify coronal plane displacement associated with distal radius fractures (DRFs), and to understand their relationship to radial inclination (RI).

This paper investigates whether cortical comminution and intra-articular involvement can predict displacement in distal radius fractures by using a classification that includes volar comminution as a separate parameter. A prospective multicentre study involving non-operative treatment of distal radius fractures in 387 patients aged between 15 and 74 years (398 fractures) was conducted. The presence of cortical comminution and intra-articular involvement according to the Buttazzoni classification is described. Minimally displaced fractures were treated with immobilisation in a cast while displaced fractures underwent closed reduction with subsequent immobilisation. Radiographs were obtained after reduction, at 10 to 14 days and after union. The outcome measure was re-displacement or union. In fractures with volar comminution (Buttazzoni type 4), 96% (53 of 55) displaced. In intra-articular fractures without volar comminution (Buttazzoni 3), 72% (84 of 117) displaced. In extra-articular fractures with isolated dorsal comminution (Buttazzoni 2), 73% (106 of 145) displaced while in non-comminuted fractures (Buttazzoni 1), 16 % (13 of 81 ) displaced. A total of 32% (53 of 165) of initially minimally displaced fractures later displaced. All of the initially displaced volarly comminuted fractures re-displaced. Displacement occurred in 31% (63 of 205) of fractures that were still in good alignment after 10 to 14 days. . Regression analysis showed that volar and dorsal comminution predicted later displacement, while intra-articular involvement did not predict displacement. Volar comminution was the strongest predictor of displacement. Cite this article: Bone Joint J 2014;96-B:978–83

In the management of a pelvic fracture prompt recognition of an unstable fracture pattern is important in reducing mortality and morbidity. It is believed that a fracture of the transverse process of L5 is a predictor of pelvic fracture instability. However, there is little evidence in the literature to support this view. The aim of this study was to determine whether a fracture of the transverse process of L5 is a reliable predictor of pelvic fracture instability. We reviewed our hospital trauma database and identified 80 patients who sustained a pelvic fracture between 2006 and 2010. There were 32 women and 48 men with a mean age of 40 years (10 to 96). Most patients were injured in a road traffic accident or as a result of a fall from a height. A total of 41 patients (51%) had associated injuries. The pelvic fractures were categorised according to the Burgess and Young classification. There were 45 stable and 35 unstable fractures. An associated fracture of the transverse process of L5 was present in 17 patients; 14 (40%) of whom had an unstable fracture pattern. The odds ratio for an unstable fracture of the pelvis in the presence of a fracture of the transverse process of L5 was 9.3 and the relative risk was 2.5. A fracture of the transverse process of L5 in the presence of a pelvic fracture is associated with an increased risk of instability of the pelvic fracture. Its presence should alert the attending staff to this possibility

Limb-injury severity scores are designed to assess orthopaedic and vascular injuries. In Gustilo type-IIIA and type-IIIB injuries they have poor sensitivity and specificity to predict salvage or outcome. We have designed a trauma score to grade the severity of injury to the covering tissues, the bones and the functional tissues, grading the three components from one to five. Seven comorbid conditions known to influence the management and prognosis have been given a score of two each. The score was validated in 109 consecutive open injuries of the tibia, 42 type-IIIA and 67 type-IIIB. The total score was used to assess the possibilities of salvage and the outcome was measured by dividing the injuries into four groups according to their scores as follows: group I scored less than 5, group II 6 to 10, group III 11 to 15 and group IV 16 or more. A score of 14 to indicate amputation had the highest sensitivity and specificity. Our trauma score compared favourably with the Mangled Extremity Severity score in sensitivity (98% and 99%), specificity (100% and 17%), positive predictive value (100% and 97.5%) and negative predictive value (70% and 50%), respectively. A receiver-operating characteristic curve constructed for 67 type-IIIB injuries to assess the efficiency of the scores to predict salvage, showed that the area under the curve for this score was better (0.988 (± 0.013 . sem. )) than the Mangled Extremity Severity score (0.938 (± 0.039 . sem. )). All limbs in group IV and one in group III underwent amputation. Of the salvaged limbs, there was a significant difference in the three groups for the requirement of a flap for wound cover, the time to union, the number of surgical procedures required, the total days as an in-patient and the incidence of deep infection (p < 0.001 for all). The individual scores for covering and functional tissues were also found to offer specific guidelines in the management of these complex injuries. The scoring system was found to be simple in application and reliable in prognosis for both limb-salvage and outcome measures in type-IIIA and type-IIIB open injuries of the tibia

The aim of this study was to define the long-term outcome following adolescent clavicle fracture.

We retrospectively reviewed all adolescent fractures presenting to our region (13–17years) over a 10-year period. Patient reported outcomes were undertaken at a minimum of 4 years post-injury (QuickDASH and EQ-5D) in completely displaced midshaft fractures (Edinburgh 2B, >2cm displacement, n=50) and angulated midshaft fractures (Edinburgh 2A2, >30 degrees angulation, n=32).

677 clavicle fractures were analysed. The median age was 14.8 (IQR 14.0–15.7) and 89% were male. The majority were midshaft (n=606, 89.5%) with either angulation (39.8%) or simple fully displaced (39.1%). Only 3% of midshaft fractures underwent acute fixation (n=18/606), all of which were fully displaced. The incidence of refracture following non-operative management of midshaft fractures was 3.2% (n=19/588), all united with non-operative management. Fracture type, severity of angulation or displacement was not associated with risk of refracture. There was one case of non-union encountered following non-operative management of all displaced midshaft fractures (0.4%, n=1/245). At a mean of 7.6 years following injury, non-operative management of both displaced and angulated fractures had a median QuickDASH was 0.0 (IQR 0.0–2.3), EQ-5D was 1.0 (IQR 1.0–1.0). 97% of angulated fractures and 94% of displaced fractures were satisfied with their final shoulder function.

We conclude that Non-operative management of adolescent midshaft clavicle fractures result in excellent functional outcomes with a low rate of complications at long-term follow up. The relative indications for surgical intervention for clavicle fractures in adults do not appear to be applicable to adolescents.

Hip fractures are associated with excess mortality, and several studies have pointed out the burden on society health care costs and the need to optimize cost effectiveness in treatment. The goal of our study was to investigate if patients with a higher risk of death after hip fracture could be identified using routine blood tests taken on admission. All 530 hip fracture patients admitted to the Department of Orthopedics, Bispebjerg University Hospital from October 2008 till December 2009 were included prospectively. Patients under the age of 60 (n = 39) were excluded. Furthermore, because the purpose was to identify blood tests at the time of admission that could predict outcome, we only included patients that had project blood samples taken at the day of admission resulting in 324 hip fracture patients for further analysis. Follow up data on mortality were obtained from the national civil registry the first of February 2010. Predictors for mortality were determined by logistic and cox regression models. P < 0.05 was regarded as statistically significant. Of the 324 hip fracture patients under study, 66 (20%) died within the study period. The results of stepwise Cox multivariate regression models for survival during the first three months after admission revealed that age, plasma creatinine and albumin predict mortality. The hazard ratios were 1.04 (95% CI: 1.005–1.09, p = 0.02), 1.01 (per unit increase)(95% CI: 1.01–1.02, p<0.0001), and 0.87 (95% CI: 0.80–0.94, p = 0.002) for age, plasma creatinine and albumin respectively. The 90 day mortality was 13% and 42% in patients with normal and elevated plasma creatinine levels respectively. Hip fracture patients are known to have a high risk of post- operative mortality. Our findings suggest that it might be possible to identify at- risk patients that could possibly benefit from increased attention the first months following surgery using already available blood samples

Aims

Using tibial shaft fracture participants from a large, multicentre randomized controlled trial, we investigated if patient and surgical factors were associated with health-related quality of life (HRQoL) at one year post-surgery.

The aim of this study was to examine the rates and potential risk factors for 28-day re-admission following a fracture of the hip at a high-volume tertiary care hospital. We retrospectively reviewed 467 consecutive patients with a fracture of the hip treated in the course of one year. Causes and risk factors for unplanned 28-day re-admissions were examined using univariate and multivariate analysis, including the difference in one-year mortality. A total of 55 patients (11.8%) were re-admitted within 28 days of discharge. The most common causes were pneumonia in 15 patients (27.3%), dehydration and renal dysfunction in ten (18.2%) and deteriorating mobility in ten (18.2%). A moderate correlation was found between chest infection during the initial admission and subsequent re-admission with pneumonia (r = 0.44, p < 0.001). A significantly higher mortality rate at one year was seen in the re-admission group (41.8% (23 of 55) vs 18.7% (77 of 412), p < 0.001). Logistic regression analysis identified advancing age, admission source, and the comorbidities of diabetes and neurological disorders as the strongest predictors for re-admission. Early re-admission following hip fracture surgery is predominantly due to medical causes and is associated with higher one-year mortality. The risk factors for re-admission can have implications for performance-based pay initiatives in the NHS. Multidisciplinary management in reducing post-operative active clinical problems may reduce early re-admission

There is no absolute method of evaluating healing of a fracture of the tibial shaft. In this study we sought to validate a new clinical method based on the systematic observation of gait, first by assessing the degree of agreement between three independent observers regarding the gait score for a given patient, and secondly by determining how such a score might predict healing of a fracture. We used a method of evaluating gait to assess 33 patients (29 men and four women, with a mean age of 29 years (15 to 62)) who had sustained an isolated fracture of the tibial shaft and had been treated with a locked intramedullary nail. There were 15 closed and 18 open fractures (three Gustilo and Anderson grade I, seven grade II, seven grade IIIA and one grade IIIB). Assessment was carried out three and six months post-operatively using videos taken with a digital camera. Gait was graded on a scale ranging from 1 (extreme difficulty) to 4 (normal gait). Bivariate analysis included analysis of variance to determine whether the gait score statistically correlated with previously validated and standardised scores of clinical status and radiological evidence of union. An association was found between the pattern of gait and all the other variables. Improvement in gait was associated with the absence of pain on weight-bearing, reduced tenderness over the fracture, a higher Radiographic Union Scale in Tibial Fractures score, and improved functional status, measured using the Brazilian version of the Short Musculoskeletal Function Assessment questionnaire (all p < 0.001). Although further study is needed, the analysis of gait in this way may prove to be a useful clinical tool

Aims

We aimed to determine the effect of dementia and Parkinson’s disease on one, three and 12-month mortality following surgery for fracture of the hip in elderly patients from an Asian population.

The capacity for physiotherapy to improve the outcome after fracture of the distal radius is unproven. We carried out a randomised controlled trial on 96 patients, comparing conventional physiotherapy with a regime of home exercises. The function of the upper limb was assessed at the time of removal of the plaster cast and at three and six months after injury. Factors which may predict poor outcome in these patients were sought. Grip strength and hand function did not significantly differ between the two groups. Flexion and extension of the wrist were the only movements to improve with physiotherapy at six months (p = 0.001). Predictors of poor functional outcome were malunion and impaired function before the fracture. These patients presented with pain, decreased rotation of the forearm and low functional scores at six weeks. Our study has shown that home exercises are adequate rehabilitation after uncomplicated fracture of the distal radius, and routine referral for a course of physiotherapy should be discouraged. The role of physiotherapy in patients at high risk of a poor outcome requires further investigation

Introduction. In valgus knees, ligament balance remain difficult when implanting a total knee arthroplasty (TKA), this leads some authors to systematically propose the use of constrained devices. Others prefer reserving higher constraints to cases where it is not possible to obtain final satisfactory balance: less than 5 of residual frontal laxity in extension in each compartment, and a tibiofemoral gap difference not in excess to 3mm between flexion and extension. The goal of the study was to assess if is possible to establish preoperative criteria that can predict a constrained design prosthetic implantation at surgery. Materials and Methods. A consecutive series of 93 total knee prostheses, implanted to treat a valgus deformity of more than 5 was retrospectively analysed. Preoperatively, full weight bearing long axis AP views A-P were performed: hip knee angle (HKA) averaged 195 (186 to 226), 36 knees had more than 15 of valgus, and 19 others more than 20 of valgus. Laxity was measured by stress radiographies with a TelosTM system at 100 N. Fifty-two knees had preoperative laxity in the coronal plane of more than 10. Fourteen knees had more than 5 laxity on the convex (medial) side, 21 knees had more than 10 laxity on the concave (lateral) side. Statistical assessment, using univariate analysis, identified the factors that led, at surgery, to an elevated constraint selection level; these factors of independence were tested by multivariate analysis. Logistical regression permitted the classification of the said factors by their odds ratios (OR). Results. High-constraints prostheses (CCK type) were used in 26 out of 93 TKA, the other TKA were regular posterostabilized (PS) prostheses. Statistically, the preoperative factors that led to the choice of a constrained prosthesis were: (1) valgus severity as measured by HKA (PS = (PS = 193, CCK = 198), (2) increased posterior tibial slope (PS = 4.8, CCK = 6.5), (3) low patellar height (using Blackburne and Peel index PS = 0.89, CCK = 0.77), (4) severity of laxity in valgus (PS = 2.3, CCK = 4.3). Among all these factors, the only independent one was laxity in valgus (convex side laxity) (p = 0.0008). OR analysis showed a two-fold increased probability of implanting an elevated constraints prosthesis for each one degree increment of laxity in valgus. Discussion. This study demonstrated that it was not the valgus angle severity but rather the convex medial side laxity that increased the frequency of constrained prostheses implantation. Other factors, as a low patellar height or an elevated posterior tibial slope, when associated, potentiate this possible prosthetic switch (to higher constraints) and should make surgeons aware, in these situations, of encountering difficulties when establishing ligament balance