Aims. While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes. Methods. This study included 136 patients undergoing robotic arm-assisted medial UKA between January 2018 and December 2022. The study included 75 males (55.1%) and 61 (44.9%) females, with a mean age of 67.1 years (45 to 90). Patients were divided into three study groups based on the degree of preoperative FFD: ≤ 5°, 5° to ≤ 10°, and > 10°. Intraoperative optical motion capture technology was used to assess pre- and postoperative FFD. Clinical FFD was measured pre- and postoperatively at six weeks and one year following surgery. Preoperative and one-year postoperative Oxford Knee Scores (OKS) were collected. Results. Overall, the median preoperative navigated (NAV) FFD measured 6.0° (IQR 3.1 to 8), while the median postoperative NAV FFD was 3.0° (IQR 1° to 4.4°), representing a mean correction of 49.2%. The median preoperative clinical FFD was 5° (IQR 0° to 9.75°) for the entire cohort, which decreased to 3.0° (IQR 0° to 5°) and 2° (IQR 0° to 3°) at six weeks and one year postoperatively, respectively. A statistically significant improvement in PROMs compared with baseline was evident in all groups (p < 0.001). Regression analyses showed that participants who experienced a larger FFD correction, showed greater improvement in PROMs (β = 0.609, p = 0.049; 95% CI 0.002 to 1.216). Conclusion. This study found that UKA was associated with an approximately 50% improvement in preoperative FFD across all three examined groups. Participants with greater correction of FFD also demonstrated larger OKS gains. These findings could prove a useful augment to clinical decision-making regarding candidacy for UKA and anticipated improvements in FFD

Fixed flexion deformities are common in osteoarthritic knees that are indicated for total knee arthroplasty. The lack of full extension at the knee results in a greater force of quadriceps contracture and energy expenditure. It also results in slower walking velocity and abnormal gait mechanics, overloading the contralateral limb. Residual flexion contractures after TKA have been associated with poorer functional scores and outcomes. Although some flexion contractures may resolve with time after surgery, a substantial percentage will become permanent. Therefore, it is essential to correct fixed flexion deformities at the time of TKA, and be vigilant in the post-operative course to maintain the correction. Surgical techniques to address pre-operative flexion contractures include: adequate bone resection, ligament releases, removal of posterior osteophytes, and posterior capsular releases. Post-operatively, extension can be maintained with focused physiotherapy, a specially modified continuous passive motion machine, a contralateral heel lift, and splinting

Between July 2000 and April 2004, 19 patients with bilateral spastic cerebral palsy who required an assistive device to walk had combined lengthening-transfer of the medial hamstrings as part of multilevel surgery. A standardised physical examination, measurement of the Functional Mobility Scale score and video or instrumented gait analysis were performed pre- and post-operatively. Static parameters (popliteal angle, flexion deformity of the knee) and sagittal knee kinematic parameters (knee flexion at initial contact, minimum knee flexion during stance, mean knee flexion during stance) were recorded. The mean length of follow-up was 25 months (14 to 45). Statistically significant improvements in static and dynamic outcome parameters were found, corresponding to improvements in gait and functional mobility as determined by the Functional Mobility Scale. Mild hyperextension of the knee during gait developed in two patients and was controlled by adjustment of their ankle-foot orthosis. Residual flexion deformity > 10° occurred in both knees of one patient and was treated by anterior distal femoral physeal stapling. Two children also showed an improvement of one level in the Gross Motor Function Classification System

We investigated fixed flexion deformity (FFD) after total knee replacement (TKR). Data relating to 369 cruciate-retaining unilateral TKRs performed at a single institution were collected prospectively. Fixed flexion was measured pre-operatively and at one week, six months, 18 months, three years and five years after surgery. Using binary logistic regression, pre-operative FFD was a predictor of post-operative FFD > 10° at one week (p = 0.006) and six months (p = 0.003) following surgery. Gender was a predictor at one week (p = 0.0073) with 24% of women showing a FFD > 10° compared with 37% of men. We have shown that a gradual improvement in knee extension can be expected up to three years after surgery in knees with FFD. By this time residual FFD is mild or absent in the majority of patients, including those who had a severe pre-operative FFD

One of the objectives of knee replacement is to correct flexion deformity, the frequent consequence of rheumatoid arthritis and osteoarthritis. A review of 697 primary and revision replacements carried out between 1969 and 1985 and followed up from 1 to 16 years found that such deformity was present in 61% of knees before the primary operation. Replacement reduced this to 17% and the improvement was usually maintained. The deformity was present in only 21% of the replacements which required revision and the second operation reduced this to 8%. Flexion contractures affected rheumatoid knees more often and more seriously than osteoarthritic knees, but arthroplasty was more successful in correcting the deformity in the former. All of the 11 types of prosthesis used achieved some degree of correction, but the Walldius hinge and the variants of the Freeman condylar design were the most successful. Surprisingly, the best outcome, in terms of pain and reduced need for revision, was found in the rheumatoid knees most seriously deformed before operation, but this association was absent in the osteoarthritic knees. Postoperative deformity in knees without pain or extreme weakness did not appear to influence the patients' ability to walk or to use stairs or a chair, as measured by unexacting tests in the clinic

We report the case of a child with cerebral palsy and spastic diplegia treated for bilateral fixed flexion of the knee by bilateral hamstring lengthening. An attempt to straighten the legs from 90 degrees to 20 degrees flexion damaged the sciatic nerve. There are no objective means of estimating how much deformity can be reduced safely. We present a method of calculating the extra strain in the sciatic nerve produced by reducing a flexion deformity. The result, combined with clinical judgement, provides guidelines for safe corrective surgery

The June 2023 Wrist & Hand Roundup. 360. looks at: Residual flexion deformity after scaphoid nonunion surgery: a seven-year follow-up study; The effectiveness of cognitive behavioural therapy for patients with concurrent hand and psychological disorders; Bite injuries to the hand and forearm: analysis of hospital stay, treatment, and costs; Outcomes of acute perilunate injuries - a systematic review; Abnormal MRI signal intensity of the triangular fibrocartilage complex in asymptomatic wrists; Patient comprehension of operative instructions with a paper handout versus a video: a prospective, randomized controlled trial; Can common hand surgeries be undertaken in the office setting?; The effect of corticosteroid injections on postoperative infections in trigger finger release

In a consecutive series of 87 operations for knee replacement prospective observations were made of the pattern of articular destruction in the form of a triangle of erosion or osteophyte formation, which is seen on the medial femoral condyle, sometimes with an associated strip on the lateral femoral condyle. These areas represent the surfaces which are normally in contact with the anterior horns of the menisci when the knee is fully extended. The lesions in question were found only in association with a flexion contracture in 84 out of the 87 cases.

Reconfiguration of elective orthopaedic surgery presents challenges and opportunities to develop outpatient pathways to reduce surgical waiting times. Dupuytren's disease (DD) is a benign progressive fibroproliferative disorder of the fascia in the hand, which can be disabling. Percutaneous-needle-fasciotomy (PNF) can be performed successfully in the outpatient clinic. The Aberdeen hand-service has over 10 years' experience running dedicated PNF clinics. NHS Grampian covers a vast area of Scotland receiving over 11749 referrals to the orthopaedic unit yearly. 250 patients undergone PNF in the outpatient department annually. 100 patients who underwent PNF in outpatients (Jan2019–Jan2020). 79M, 21F. Average age 66 years range (29–87). 95 patients were right hand dominant. DD risk factors: 6 patients were diabetic, 2 epileptic, 87 patients drank alcohol. 76 patients had a family history of DD. Disease severity, single digit 20 patients, one hand multiple digits in 15 patients, bilateral hands in 65 patients of which 5 suffered form ectopic manifestation suggestive of Dupuytren's diasthesis. Using Tubiana Total flexion deformity score pre and post fasciotomy. Type 1 total flexion deformity (TFD) between 0–45 degrees pre PNF n=60 post N= 85, Type 2 TFD 45–90 degrees pre PNF n=18 post N=9, Type 3 TFD 90–135 pre PNF n=15 post N= 5, Type 4 TFD >135 pre PNF n=1 post PNF N=1. Using Chi-square statistical test, a significant difference was found at the p<0.05 between the pre and post PNF TFD. Complication: 8 recurrence, 1 skin tear. No patients sustained digital nerve injury. Outpatients PNF clinics are a valuable resource

Abstract. Introduction. This study compared biomechanical and functional parameters of a total knee arthroplasty (TKA) implant (Cemented Zimmer Hi-Flex) against healthy older adults to determine whether knee biomechanics was restored in this patient population. Methodology. Patients with a primary TKA and healthy adults >55 years old with no musculoskeletal deficits or arthritis participated. Bilateral knee range of motion (RoM) was assessed with a goniometer, then gait patterns were analysed with a 3D motion-capture system. An arthrometer then quantified anterior-posterior laxity of each knee. Statistical analyses were performed in SPSS (α=0.05; required sample size: n=21 per group). Results. 25 knees were replaced in 21 patients. Nine presented with fixed flexion deformities (FFD) (13.3±5.6°). FFDs were abolished intraoperatively, and the average flexion increased from 124.8±9.1° to 130.9±5.8°. At 9.6±3.2 years postoperatively, the patients achieved poorer RoM than healthy controls (n=23); p<0.0001. These differences were due to limited flexion in the knee. Patients also failed to achieve the same degree of flexion as controls bilaterally during gait. No differences were observed during mid-flexion; a state that has been associated with instability (p=0.614). There were no differences between groups in knee laxity. Conclusion. Patients in this study had similar gait patterns to healthy older adults during mid-flexion, and were no more likely to exhibit anterior-posterior translation of the knee >7mm; a known risk factor of instability. However, the flexion range was poorer. This led to bilateral pathological knee flexion patterns during gait. Further research should identify the cause of these limitations

Percutaneous flexor tenotomy involves cutting the flexor digitorum tendons to correct claw toe deformity to treat apical pressure areas and prevent subsequent infection in patients with peripheral neuropathy. Performing this under ultrasound guidance provides reassurance of complete release of the tendon and increases procedural safety. This study is a retrospective case series evaluating the effectiveness, safety, and patient satisfaction of performing percutaneous ultrasound-guided flexor tenotomy in an outpatient setting. People with loss of protective sensation, a digital flexion deformity, and an apical toe ulcer or pre-ulcerative lesion who presented to our institution between December 2019 and June 2022 were included in this study. Participants were followed-up at a minimum of 3 months. Time to ulcer healing, re-ulceration rate, patient satisfaction, and complications were recorded. An Australian cost analysis was performed comparing this procedure performed in rooms versus theatres. There were 28 ulcers and 41 pre-ulcerative lesions. A total of 69 tenotomy procedures were performed on 38 patients across 52 episodes of care. The mean time to ulcer healing was 22.5 +/- 6.4 days. There were 2 cases of re-ulceration. 1 patient sustained a transfer lesion. There were four toes that went onto require amputation, all in the setting of pre-existing osteomyelitis. 94% of patients strongly agreed that they were satisfied with the outcome of the procedure. Costs saved were estimated to be $1426. Flexor tenotomy is a minimally invasive procedure that can be performed in the outpatient setting, and therefore without delay to treatment, reducing risk of ulcer progression and need for subsequent amputation. This is the first study to report on flexor tenotomy under ultrasound-guidance. Ultrasound-guided percutaneous flexor tenotomy is safe and effective, with high patient satisfaction and low recurrence rates. This performance in the outpatient setting ensures significant time and cost savings for both the practitioner and patient

This study was performed at Assiut University, Assiut, Egypt. Anterior distal femoral hemiepiphysiodesis (ADFH) using intra-articular plates for the correction of paediatric fixed knee flexion deformities (FKFD) has two main documented complications: postoperative knee pain and implant loosening. This study describes a biomechanical analysis and a preliminary report of a novel extra-articular technique for ADFH. Sixteen femoral sawbones were osteotomized at the level of the distal femoral physis and fixed by rail frames to allow linear distraction simulating longitudinal growth. Each sawbone was tested twice: first using the conventional technique with medial and lateral parapatellar eight plates (group A) and then with the plates inserted in the proposed novel location at the most anterior part of the medial and lateral surfaces of the femoral condyles with screws in the coronal plane (group B). Gradual distraction was performed, and the resulting angular correction was measured. Strain gauges were attached to the plates, and the amount of strain (and equivalent stress) over the plates was recorded. This technique was then applied to 9 paediatric FKFDs of different aetiologies. The preoperative FKFD and the amount of subsequent angular correction were measured. The amount of angular correction was higher in group B at 5, 10-, and 15-mm of distraction (p<0.001). The maximum and overall stresses measured throughout the distraction process were higher in group A (p<0.001). The mean FKFD improved from 24 ± 9° preoperatively to 9 ± 7° after 10 ± 3° months (p<0.001). The correction rate was 1.81 ± 0.65° per month. During ADFH, the fixation of the eight plates in the coronal plane at the anterior part of the femoral condyles may produce greater correction and lower stresses over the implants as compared to the conventional technique. Preliminary results from our initial series seem to support the effectiveness of this technique with respect to the degree of angular correction achieved

Introduction. At Sheffield Children's Hospital, treatment of leg length discrepancy is a common procedure. Historically, this has been done with external fixators. With the development in intramedullary technology, internal nails have become the preferred modality for long bone lengthening in the adolescent population. However, it is important to review whether this technology practically reduces the known challenges seen and if it brings any new issues. Therefore, the aim of this review is to retrospectively evaluate the therapeutic challenges of 16 fit-bone intramedullary femoral lengthening's at Sheffield Children's Hospital between 2021–2022. Materials & Methods. The international classification of function (ICF) framework was used to differentiate outcomes. The patient's therapy notes were retrospectively reviewed for themes around structural, activity and participation limitation. The findings were grouped for analysis and the main themes presented. Results. There were 8 males, mean age 17.4 years (range 17–18) and 8 females, mean age 15.9 years (range 14–18). 5 right and 11 left femurs were lengthened. Underlying pathology varied amongst the 16 patients. All patients went into a hinged knee brace post operatively. Structural limitations included: pain, fixed flexion deformity of the knee, loss of knee flexion, quadriceps muscle lag, muscle spasms and gluteal weakness. The primary activity limitation was reduced weight bearing with altered gait pattern. Participation limitations included reduced school attendance and involvement in activities with peers. Access to Physiotherapy from local services varied dramatically. Five of the cohort have completed treatment. Conclusions. Anecdotally, intramedullary femoral lengthening nails have perceived benefits for families compared to external fixators in the adolescent population. However, there remain musculoskeletal and psychosocial outcomes requiring therapeutic management throughout the lengthening process and beyond. Therefore, quantifying these outcomes is essential for measuring the impact on each patient for comparison. To interpret these themes, we need to evaluate the outcomes objectively, this was not done consistently in this review. Future research should look at outcome measures that are sensitive to all aspects of the ICF. With an aim of improving the therapeutic treatment provided and the overall outcome for the children treated

Aims. The aims of this prospective study were to determine the effect of osteophyte excision on deformity correction and soft- tissue gap balance in varus knees undergoing total knee arthroplasty (TKA). Patients and Methods. Limb deformity in coronal (varus) and sagittal (flexion) planes, medial and lateral gap distances in maximum knee extension and 90° knee flexion and maximum knee flexion were recorded before and after excision of medial femoral and tibial osteophytes using computer navigation in 164 patients who underwent 221 computer-assisted, cemented, cruciate- substituting TKAs. Results. Mean varus and flexion deformities of 4.5°±3° (0.5° to 30° varus) and 4.9°±5.9° (−15° hyperextension to 30° flexion) reduced significantly (p<0.0001) to mean varus deformity of 1°±2.3° and mean flexion deformity of 2.7°±4.2° after excision of medial femoral and tibial osteophytes. The mean medio-lateral (ML) soft-tissue gap difference in maximum knee extension and 90°knee flexion of 2.7±3.6mm and 0.7±2.6mm reduced significantly (p<0.0001) to mean ML soft-tissue gap difference of 0.7±2.5mm in maximum knee extension and 0.1±1.9mm in 90°knee flexion. The mean maximum knee flexion (122.8°±8.4°) increased significantly to mean maximum knee flexion of (125°±8°). Conclusion. Excision of medial femoral and tibial osteophytes during TKA in varus knees significantly improves varus and flexion deformities, mediolateral soft-tissue gap imbalance in maximum extension and in 90°knee flexion and maximum knee flexion. Clinical Relevance. Excision of medial femoral and tibial osteophytes can be a useful, initial step towards achieving deformity correction and gap balance without having to resort to soft-tissue release during TKA in varus knees

Fixed flexion deformity is common in neglected cases of advanced arthritis of the knee. The need and means of complete correction of fixed flexion deformity remains controversial. We analysed 60 patients of advanced arthritis with severe flexion deformity > 300 who underwent total knee arthroplasty between January 2002 to January 2008. The age ranged from 54 to 78 years (mean age of 62 years). All surgeries were performed using posterior cruciate substituting implant. Patients were followed for an average period of 42 months. All patients were operated in a single stage. Distal femoral over-resection was done in addition to posterior, postero-medial and postero-lateral release. Posterior release was done upto the linea aspera. In 2 cases posterior capsular was released directly. A criteria was developed for sequential release on the basis of degree of flexion deformity. Flexion deformity was fully corrected in 48 cases where as 50 of residual flexion remained in 5 cases with preoperative deformity of 40–600 and 100 residual flexion remained in 6 cases with preoperative deformity > 600. One patient with pre op fixed flexion deformity of 90* had to be treated with arthrodesis. Our experience suggest that predetermined routine femoral over-resection in moderate to severe flexion deformity prior to balancing knee is not fraught with complications if our criteria are followed. Additional bony cuts (over-resection) and posterior soft tissue release is complementary to each other in correction of flexion deformity and it should be a sequential release. This technique saves time, reduces intraoperative difficulties and helps to correct flexion deformity maximally

Introduction. The objective of this study was to assess the effect of PCL resection on flexion-extension gaps, mediolateral soft tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilised total knee arthroplasty (TKA). Methods. This prospective study included 110 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted posterior-stabilised TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps pre- and post-PCL resection in knee extension and 90 degrees knee flexion. This study included 54 males (49.1%) and 56 females (50.9%) with a mean age of 68 ± 6.2 years at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1 ± 4.4 degrees varus. Results. PCL resection increased the flexion gap more than the extension gap in the medial (2.4 ± 1.5mm vs 1.3 ± 1.0mm respectively, p<0.001) and lateral (3.3 ± 1.6mm vs 1.2 ± 0.9mm respectively, p<0.01) compartments. The gap differences following PCL resection created mediolateral laxity in flexion (gap difference: 1.1 ± 2.5mm, p<0.001) but not in extension (gap difference: 0.1 ± 2.1mm, p=0.51). PCL resection improved overall FFD (6.3 ± 4.4° preoperatively vs 3.1 ± 1.5° postoperatively, p<0.001). There was a strong positive correlation between preoperative FFD and change in FFD following PCL release (Pearson correlation coefficient = 0.81, p<0.001). PCL resection did not affect overall limb alignment (change in alignment: 0.2 ± 1.2 degrees valgus, p=0.60). Conclusion. PCL resection creates flexion-extension mismatch by increasing the flexion gap proportionally more than the extension gap. The increase in the lateral flexion gap is greater than the increase in medial flexion gap, which creates mediolateral laxity in flexion. Improvements in FFD following PCL resection are dependent on the degree of deformity prior to PCL resection. Bone resection, implant positioning, and periarticular soft tissue balancing should account for these changes in flexion-extension gaps, mediolateral laxity, and fixed flexion deformity following PCL resection in PS TKA. For figures, tables, or references, please contact authors directly

Introduction: Majority of children with cerebral palsy patients suffer from fixed flexion contractures of their knees. Procedures commonly used to correct knee flexion deformities include hamstring release, anterior femoral hemiepiphyseodesis and femoral extension osteotomies. The latter procedure can cause neurovascular complications. Femoral stapling procedures are not very popular because of a theoretical risk of permanent physeal closure. We present our initial experience in correction of knee flexion deformity by using the 8-plate technique. This uses guided growth in the distal femoral physis to achieve gradual correction of the knee flexion deformity. Materials and Methods: We reviewed a consecutive series of 25 children with fixed flexion deformity of the knee who underwent anterior femoral hemiepiphysiodesis using a two-hole plate (8-plate) between April 2005 and April 2008. The pre-operative and postoperative knee flexion deformity (in degrees) and complication rates were also recorded. Paired t-Test was undertaken to assess the correction in the fixed flexion deformity post-operatively. Results: Total number of patients – 25, male:female = 19:6. Total number of limbs – 46. The mean age of the patients was 11.04 years (range between 4–16). Mean follow up time for the patients after they had undergone the procedure was 16.2 months (range 3 – 34). The Mean correction achieved − 21.52 degrees (range 5 – 40). Mean correction per month − 2.05 degrees. A paired ‘t’ test showed the correction was found to be highly statistically significant (p value < 0.001). Conclusion: We conclude that this is a simple technique with few complications to date. The learning curve for this procedure is 1 case. All patients in our series have shown promising results, with sustained gradual correction to date

Introduction. We have previously published limb lengthening using external fixation in pathological bone diseases. We would like to report a case series of femoral lengthening using the PRECICE system in a similar pathological group especially looking at it's feasibility and complications. Materials and Methods. This is a case series of four patients, two patients with osteogenesis imperfecta and two with Ollier's disease, who underwent femoral lengthening via distraction osteogenesis using the PRECICE intramedullary nail system. It was a retrospective study from a prospective database from clinical records and radiographs. Results. The mean age at the time of surgery was 15.5 years, the mean preoperative leg length discrepancy was 30mm, and the mean distraction distance achieved was 28.75mm. Since these patients were of shorter heigh, limb lengthening was considered. All 4 patients had successful insertion of the nail. The outcomes noted from the 4 patients are collated, with several complications occurring including delayed femoral union, fixed flexion deformity of the hip, persisting pain and quadriceps weakness. Those with Ollier's disease underwent an increased rate of distraction to prevent premature healing. The implications of long-term bisphosphonate therapy in OI are discussed with regards to the risk of delayed femoral union and intra-operative fracture. Conclusions. Intramedullary femoral lengthening in pathological bone disease is possible, but the surgeon needs to give attention to certain details. The regenerate formation is based on the background pathology irrespective of the hardware used. There is much more compliance with the nail technique

The purpose of this study is to investigate the feasibility of surgical correction of moderate flexion deformity during total knee arthroplasty by recreating the posterior condylar recess following certain sequence of surgical principles without extra-resection of bone from the distal femur or proximal tibia. The hypothesized surgical protocol was applied in 52 consecutive primary TKAs with moderate flexion deformity. Preoperative and residual postoperative flexion deformity was recorded. Intraoperatively, extension and flexion gap widths were recorded before and after surgical correction. Fixed flexion deformity has improved from a preoperative mean value of 24.8±6.4 to a postoperative residual value of 3.2±1.8 (p value < 0.001). Extension and flexion gap widths have increased by a mean value of 3.8±0.4 mm and 4.1±0.7 mm respectively (p value < 0.005). There was no significant difference between the changes in the extension and flexion gaps. The original flexion/extension gap width mismatch (3.2±0.5mm) was compensated for by an upsized femoral component. The statistically significant changes has demonstrated the efficiency of the hypothesized surgical protocol for management of flexion deformity during TKA added to the benefits of bone conservation for future revision surgery, preservation of surface area for collateral attachments, and establishment of the joint line at the correct level

Aims. The aim of this study was to assess the effect of posterior cruciate ligament (PCL) resection on flexion-extension gaps, mediolateral soft-tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilized (PS) total knee arthroplasty (TKA). Patients and Methods. This prospective study included 110 patients with symptomatic osteoarthritis of the knee undergoing primary robot-assisted PS TKA. All operations were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps before and after PCL resection in extension and 90° knee flexion. Measurements were made after excision of the anterior cruciate ligament and prior to bone resection. There were 54 men (49.1%) and 56 women (50.9%) with a mean age of 68 years (. sd. 6.2) at the time of surgery. The mean preoperative hip-knee-ankle deformity was 4.1° varus (. sd. 3.4). Results. PCL resection increased the mean flexion gap significantly more than the extension gap in the medial (2.4 mm (. sd. 1.5) vs 1.3 mm (. sd. 1.0); p < 0.001) and lateral (3.3 mm (. sd. 1.6) vs 1.2 mm (. sd. 0.9); p < 0.01) compartments. The mean gap differences after PCL resection created significant mediolateral laxity in flexion (gap difference: 1.1 mm (. sd. 2.5); p < 0.001) but not in extension (gap difference: 0.1 mm (. sd. 2.1); p = 0.51). PCL resection significantly improved the mean FFD (6.3° (. sd. 4.4) preoperatively vs 3.1° (. sd. 1.5) postoperatively; p < 0.001). There was a strong positive correlation between the preoperative FFD and change in FFD following PCL resection (Pearson’s correlation coefficient = 0.81; p < 0.001). PCL resection did not significantly affect limb alignment (mean change in alignment: 0.2° valgus (. sd. 1.2); p = 0.60). Conclusion. PCL resection creates flexion-extension mismatch by increasing the flexion gap more than the extension gap. The increase in the lateral flexion gap is greater than the increase in the medial flexion gap, which creates mediolateral laxity in flexion. Improvements in FFD following PCL resection are dependent on the degree of deformity before PCL resection. Cite this article: Bone Joint J 2019;101-B:1230–1237