To promote rapid bone healing, an adequate stable fixation implant with a percutaneous reduction instrument should be used for Vancouver type B1 or C fractures. The objective of this study was to describe radiographic and clinical outcomes of patients with periprosthetic fracture (PPF) around a stable femoral stem, treated with a distal femoral locking plate alone or with a cerclage cable. A total of 21 patients with PPF amenable to either a reverse distal femoral locking plate (LCP DF®) alone or with a cerclage cable, with a mean age of 75.7 years, were included. In these patients, 10 fractures were treated with a reverse LCP DF® alone and were classified as group I, and 11 additionally received a cerclage cable and were classified as group II.[Fig.1]Purpose
Materials and Methods
Purpose.
Treatment of syndesmotic injuries is a subject of ongoing controversy.
Aims of study. To assess and compare the functional, radiological and cosmetic results as well as patient satisfaction in patients treated with the IMN Device Vs Volar
Distal radius fracture is one of the most common fractures in older women (∼70,000 cases annually in Canada). Treatment of this fracture has been shifting toward surgery (mainly volar locking plate (VLP) technology), which significantly enhances surgeon's ability to maintain correction. However, current surgical outcomes are far from perfect. There is a need for an implant which maintains the corrected position (reduction), minimizes soft tissue disruption, and is technically easy to perform. A novel internal, composite-based implant was designed to achieve these ends. It is unclear, however, whether this novel implant offers similar fracture fixation as the VLP. As such, the objective of this research was to evaluate the fracture stability (assessed by calculating change in fracture length) of the novel implant and VLP under cyclic fatigue loading. Specimens: Seven radius specimens derived from older female cadavers (mean = 82.3 years, SD = 11.3 years) were used for the experiment. Preparation: A standardized dorsal wedge was removed from the cortex. The distance from the proximal and distal transverse osteotomies was 10 mm and was positioned 20 mm proximal to the tip of the radial styloid. The osteotomy removed all load-bearing capabilities of bone, equivalent to a worst-case-scenario for DRF fixation. Simulated Loading: The proximal end of the radii was potted (fixed) and positioned in a material testing system. To mimic natural loading conditions, hands were cycled between −30°/30° flexion/extension, at 0.5 Hz, for 2000 cycles, while tension load was applied to the tendons (25-N constant force per tendon, 100-N in total). Mechanical testing outcomes: A position tracking sensor used to measure change in fracture length. This change, as a function of number of cycles, was used to assess implant resistance to fatigue loading. Statistical Analysis: A paired student t-test was used to compare the change in fracture length. Level of significance was determined as 5% (p < 0.05). Changes in fracture fracture-length for both the novel implant and plate is shown in Table 1. The paired t-test indicated significant differences between the two groups in terms of change in fracture length (p = 0.026). The outcome of the novel implant ranged from very stable (change in fracture-length = 0.01 mm) to highly un-stable (2.88 mm). We believe the reason for this variance, at least in part, originates from the surgical procedures. Presumably, given that one very strong stabilization (0.01 mm) and one acceptable stabilization (0.37 mm) was obtained, future research directed towards surgical procedures may improve fracture stability. For any figures or tables, please contact authors directly.
Distal radius fractures are the most common upper extremity injury, and are increasingly being treated surgically with pre-contoured volar-locking plates. These plates are favored for their low-profile template while allowing for rigid anatomic fixation of distal radius fractures. The geometry of the distal radius is extremely complex, and little evidence within the medical literature suggests that current implant designs are anatomically accurate. The main objective of this study is to determine if anatomic alignment of the distal radii corresponds accurately with modern volar-locking plate designs. Additionally, this study will examine sex-linked differences in morphology of the distal radius. Segmented CT models of ten female cadaver (mean age, 88.7 ± 4.57 years, range, 82 – 97) arms, and ten male cadaver (mean age, 86 ± 3.59 years, range, 81 – 91) arms were created. Micro CT models were obtained for the DePuy Synthes 2.4mm Extra-articular (EA) Volar Distal Radius Plate (4-hole and 5-hole head), and 2.4mm LCP Volar Column (VC) Distal Radius Plate (8-hole and 9-hole head). Plates were placed onto the distal radii models in a 3D visualization software by a fellowship-trained orthopaedic hand surgeon. The percent contact, volar cortical angle (VCA), border and overlap of the watershed line (WSL) were measured. Both sexes showed an increase in the average VCA measure from medial to lateral columns which was statistically significant. Female VCA ranged from 28 – 36 degrees, and 38 – 45 degrees for males. WSL overlap ranged from 0 – 34.7629% for all specimens without any statistical significance. The average border distance for females was 2.58571 mm, compared to 3.52411 mm for males, with EA plates having a larger border than VC plates. The border distances had statistically significant differences between the plate types, and was approaching significance between sexes. Lastly, a maximum percent contact of 21.966 % was observed in specimen F4 at a 0.3 mm threshold. No statistical significance between plate or sex populations was observed. This study investigated the incoherency between the volar cortical angle of the distal radius, and the pre-contoured angle of volar locking plates. It was hypothesized that if the VCA measures between plate and bone were unequal then there would be an increase in watershed line overlap, and decrease in percent contact between the surfaces. Our results agreed with literature, indicating that the VCA of bone was larger than that of the EA and VC pre-contoured plates examined in this study. With distal radius fracture incidences and prevalence on the rise for elderly female patients, it is a necessity that volar locking plates be re-designed to factor in anatomical features of individual patients with a particular focus on sex differences. New designs should focus on providing smaller head sizes that are more accurately tailored to the natural contours of the volar distal radius. It is recommended that future studies incorporate expertise from multiple surgeons to diversify and further understand plate placement strategies.
Distal radius fractures (DRF) are common and the indication for surgical treatment remain controversial in patients higher than 60 years old. The purpose of the study was to review and analyze the current evidence-based literature. We performed a systematic review and meta-analysis according to PRISMA guidelines in order to evaluate the efficacy of volar locking plating (VLP) and conservative treatment in DRF in patients over 60 years old. Electronic databases including MEDLINE, CENTRAL, Embase, Web of science and Clinical Trial.gov were searched from inception to October 2020 for randomized controlled trials. Relevant article reference lists were also passed over. Two reviewers independently screened and extracted the data. Main outcomes included functional status: wrist range of motion, validated scores and grip strength. Secondary outcomes include post-operative complications and radiologic assessment. From 3009 screened citations, 5 trials (539 patients) met the inclusion criteria. All trials of this random effect meta-analysis were at moderate risk of bias due to lack of blinding. Differences in the DASH score (MD −5,91; 95% CI, −8,83; −3,00), PRWE score (MD −9.07; 95% CI, −14.57, −3.57) and grip strength (MD 5,12; 95% CI, 0,59-9,65) were statistically significant and favored VLPs. No effect was observed in terms of range of motion. Adverse events are frequent in both treatment groups, reoperation rate is higher in the VLP group. VLP may provide better functional outcomes in patients higher than 60 years old. More RCT are still needed to evaluate if the risks and complications of VLP outweigh the benefits.
Distal radius fractures are the most common osteoporotic fractures among women. The treatment of these fractures has been shifting from a traditional non-operative approach to surgery, using volar locking plate (VLP) technology. Surgery, however, is not without risk, complications including failure to restore an anatomic reduction, fracture re-displacement, and tendon rupture. The VLP implant is also marked by bone loss due to stress-shielding related to its high stiffness relative to adjacent bone. Recently, a novel internal, composite-based implant, with a stiffness less than the VLP, was designed to eradicate the shortcomings associated with the VLP implant. It is unclear, however, what effect this less-stiff implant will have upon adjacent bone density distributions long-term. The objective of this study was to evaluate the long-term effects of the two implants (the novel surgical implant and the gold-standard VLP) by using subject-specific finite element (FE) models integrated with an adaptive bone formation/resorption algorithm. Specimen: One fresh-frozen human forearm specimen (female, age = 84 years old) was imaged using CT and was used to create a subject-specific FE model of the radius. Finite element modeling: In order to simulate a clinically relevant (unstable) fracture of the distal radius, a wedge of bone was removed from the model, which was approximately 10 mm wide and centered 20 mm proximal to the tip of the radial styloid. Bone remodeling algorithm: A strain-energy density (SED) based bone remodeling theory was used to account for bone remodeling. With this approach, bone density decreased linearly when SED per bone density was less than 67.5 µJ/g and increased when it was more than 232.5 µJ/g. When it was in the lazy zone (67.5 to 232.5 µJ/g), no changes in density occurred. Boundary conditions: A 180 N quasi-static force representing the scaphoid, and a 120 N quasi-static force representing the lunate was applied to the radius. The midshaft of the radius was constrained. FE outcomes: To examine the effects of stress shielding associated with each implant, the long-term changes of bone density within proximal transverse cross-sections of radius were inspected. The regional density analysis focused on three transverse cross-sections. The transverse cross-sections were positioned proximal to the subchondral plate, and were distanced 50 (cross-section A), 57 (cross-section B), and 64 mm (cross-section C) from the subchondral endplate. For both implants in all three cross-sections, cortical bone was reserved completely at the volar side. On the dorsal side, the cortical bone was completely resorbed in the VLP model. In all cross-sections, the averaged resultant density was higher for the “novel implant”. The difference ranged from 33% (cross-section A) to 36% (cross-section C) in favor of the “novel implant”. On average, the density values of the novel implant were 34% higher in transverse cross-sections (A, B, and C). This study showed that the novel implant offered higher density distributions compared to the VLP, which suggests that the novel implant may be superior to the VLP in terms of avoiding stress shielding.
Treatment of proximal humerus fractures (PHF) is controversial in many respects, including the choice of surgical approach for fixation when using a locking plate. The classic deltopectoral (DP) approach is believed to increase the risk of avascular necrosis while making access to the greater tuberosity more difficult. The deltoid split (DS) approach was developed to respect minimally invasive surgery principles. The purpose of the present study (NCT-00612391) was to compare outcomes of PHF treated by DP and DS approaches in terms of function (Q-DASH, Constant score), quality of life (SF12), and complications in a prospective randomized multicenter study. From 2007 to 2016, all patients meeting the inclusion/exclusion criteria in two University Trauma Centers were invited to participate in the study. Inclusion criteria were: PHF Neer II/III, isolated injury, skeletal maturity, speaking French or English, available for follow-up (FU), and ability to fill questionnaires. Exclusion criteria: Pre-existing pathology to the limb, patient-refusing or too ill to undergo surgery, patient needing another type of treatment (nail, arthroplasty), axillary nerve impairment, open fracture. After consent, patients were randomized to one of the two treatments using the dark envelope method. Pre-injury status was documented by questionnaires (SF12, Q-DASH, Constant score). Range of motion was assessed. Patients were followed at two weeks, six weeks, 3-6-12-18-24 months. Power calculation was done with primary outcome: Q-DASH. A total of 92 patients were randomised in the study and 83 patients were followed for a minimum of 12 months. The mean age was 62 y.o. (+- 14 y.) and 77% were females. There was an equivalent number of Neer II and III, 53% and 47% respectively. Mean FU was of 26 months. Forty-four patients were randomized to the DS and 39 to the DP approach. Groups were equivalent in terms of age, gender, BMI, severity of fracture and pre-injury scores. All clinical outcome measures were in favor of the deltopectoral approach. Primary outcome measure, Q-DASH, was better statistically and clinically in the DP group (12 vs 26, p=0,003). Patients with DP had less pain and better quality of life scores than with DS (VAS 1/10 vs 2/10 p=0,019 and SF12M 56 vs 51, p=0,049, respectively). Constant-Murley score was higher in the DP group (73 vs 60, p=0,014). However, active external rotation was better with the DS approach (45° vs 35°). There were more complications in DS patients, with four screw cut-outs vs zero, four avascular necrosis vs one, and five reoperations vs two. Calcar screws were used for a majority of DP fixations (57%) vs a minority of DS (27%) (p=0,012). The primary hypothesis on the superiority of the deltoid split incision was rebutted. Functional outcome, quality of life, pain, and risk of complication favoured the classic deltopectoral approach. Active external rotation was the only outcome better with DS. We believe that the difficulty of adding calcar screws and intramuscular dissection in the DS approach were partly responsible for this difference. The DP approach should be used during Neer II and III PHF fixation.
Distal femur fracture is a critical issue in orthopedic trauma, because it is difficult to manage especially in cases with intra-articular fracture. Osteoporosis may cause instability of implant and increase complications. Few studies investigate on the stability of distal femur osteoporotic fracture and the behaviors under cycling. Our hypothesis was that the stiffness of construct would decrease as cycling in osteoporotic bone. Seven cadaver specimens were used in this study. Relative bone density for each specimen was evaluated using CT scanning by three known calibration phantoms scanned simultaneously with the specimen. All cadaver specimens were divided normal (group 1) and osteoporosis (group 2) in accordance with the bone density. The titanium distal femur locking plates with 6 screws placed in distal femur condyle and 4 in shaft. A 10 mm gap with 65 mm proximal to the center of articular surface and a vertical fractural line between intra-articular were created to simulate AO C2 type fracture. Each specimen was cyclically loaded in two-phase at a frequency of 2 Hz. Phase 1 was set at 1000 N for 10000 cycles. In phase 2, the load was set at 2000 N for 10000 cycles. Then, the specimen was loaded up to failure at a rate of 5 mm/min. Stiffness was evaluated from the linear portion of load-displacement curve at 2000 cycle interval.Introduction
Materials and Methods
Distal radius fractures (DRF) are common and the indication for surgical treatment remain controversial in patients higher than 60 years old. The purpose of the study was to review and analyze the current evidence-based literature. We performed a systematic review and meta-analysis according to PRISMA guidelines in order to evaluate the efficacy of volar locking plating (VLP) and conservative treatment in DRF in patients over 60 years old. Electronic databases including MEDLINE, CENTRAL, Embase, Web of science and Clinical Trial.gov were searched from inception to October 2020 for randomized controlled trials. Relevant article reference lists were also passed over. Two reviewers independently screened and extracted the data. Main outcomes included functional status: wrist range of motion, validated scores and grip strength. Secondary outcomes include post-operative complications and radiologic assessment. From 3009 screened citations, 5 trials (539 patients) met the inclusion criteria. All trials of this random effect meta-analysis were at moderate risk of bias due to lack of blinding. Differences in the DASH score (MD −5,91; 95% CI, −8,83; −3,00), PRWE score (MD −9.07; 95% CI, −14.57, −3.57) and grip strength (MD 5,12; 95% CI, 0,59-9,65) were statistically significant and favored VLPs. No effect was observed in terms of range of motion. Adverse events are frequent in both treatment groups, reoperation rate is higher in the VLP group. VLP may provide better functional outcomes in patients higher than 60 years old. More RCT are still needed to evaluate if the risks and complications of VLP outweigh the benefits.
To elucidate the molecular biology of fracture healing, murine models are preferred. We performed a study with the first internal fixation system that allows studying murine fracture healing in a controlled mechanical environment, to characterise the timing of the fracture healing cascade with this model, based on a histological evaluation. Femoral osteotomies were performed in 68 male C57BL/six mice and stabilised with locking internal fixation plates in either stiff, or defined, flexible configurations. Healing progression was studied at 10 time points between 3 and 42 days post- surgery. After surgery, mice were radiographed to confirm the correct implant positioning. After sacrifice, the extracted femora were processed for decalcified histology. Thin sections were taken as serial transverse sections and stained for subsequent histomorphometric analysis and three-dimensional reconstruction of the different fracture callus tissues. The surgery was successful in 62 animals. Only six6 (8.8%) animals had to be sacrificed due to complications during surgery. The post-operative radiographs demonstrated a high reproducibility of implant positioning and no implant failure or screw loosening occurred during the experimental period. The improved consistency in surgical technique leading to more uniform results represents a key advantage of this system over other mouse fracture healing models. As such, it may allow a reduction in the sample size needed in future murine fracture healing studies. The histological evaluation confirmed the lack of a periosteal callus, and exclusively endosteal, intramembraneous bone formation in the bones stabilised with the stiff implants. The bones that were stabilised with the more flexible internal fixation plates showed additional endochondral ossification with extensive, highly asymmetrical, periosteal callus formation. Our results demonstrate that this murine fracture model leads to different healing patterns depending on the flexibility of the chosen plate system. This allows researchers to investigate the molecular biology of fracture healing in different ossification modes by selection of the appropriate fixation.
Displaced two- to four-part fractures of the proximal humerus pose a difficult therapeutic challenge. We report the results of internal fixation of these fractures in a case series of 50 patients with a locking plate system. All fractures united with no failure of fixation. The mean constant score was 79. One patient developed avascular necrosis. Internal fixation with locking plate system in healthy active patients, disregarding their age, is a reliable method of treating displaced proximal humerus fractures. The tuberosities should be restored anatomically prior to plate application. Surgical expertise in treating shoulder conditions is essential for good functional outcome.
The aim of the study was to assess the medium term outcome for complex proximal humeral fractures treated with the long proximal humeral internal locking system (PHILOS) plate fixation. All patients who had long PHILOS plate fixation of proximal humerus fractures with metaphyseal or diaphyseal extension over a three year period at our institution were included in the study. Patients had their case notes and radiographs reviewed. Patients were also contacted to assess functional outcome using the Visual Analogue Scale (VAS) for pain, DASH, Oxford shoulder score (OSS) and Stanmore Percentage of Normal Shoulder Assessment (SPONSA). Out of an initial cohort of 34 patients, 1 died, 2 patients had unrelated illnesses resulting in them being unable to complete the assessment and 6 were lost to follow-up, leaving 25 patients (74%) for review. All patients had proximal humeral fractures with metaphyseal or diaphyseal extension requiring long plate osteosynthesis. One patient had the procedure for non union following initial treatment with an intra medullary nail and the rest were acute injuries. The patients were followed up after a mean of 27 months (range 11–60). The length of plate used varied from 5 to 12 holes for the shaft region. There was 1 wound infection. 3 patients had non unions which required bone grafting and revision internal fixation. At final follow-up, mean pain was 3.6 (95% Confidence Interval 2.5–4.8) with only 4 patients having residual pain greater than 5 on the VAS scale. Mean DASH score was 41.2 (95% CI 32.0–50.4), mean OSS was 29.1 (95% CI 24.3–33.9) and mean SPONSA was 63.9% (95% CI 50.8–77.2) The long PHILOS plate appears to represent a good treatment option for complex proximal humerus fractures with favourable medium term results and few complications.
Unstable fractures of the distal tibia are being increasingly treated by open reduction and internal fixation using pre-contoured locking plates. Functional outcome following this type of fixation has not been reported previously. The aim of this study was to functionally assess patients following MIPO fixation of distal tibial fractures. Case notes of 26 patients treated at a single centre were reviewed. The fracture type, fixation technique, complications, time to union and subsequent treatment were documented. All patients returned for functional scoring using the validated American Academy of Orthopedic Surgeons (AAOS) foot and ankle core score. Twenty-six consecutive patients were treated between 2002-2005. The majority were male, and 5 were open fractures. There were 13 AO type A, 4 type B and 9 type C fractures. Mean follow up was 20 months. Average time from injury to surgery was 2.5 days. All fractures were treated by a MIPO technique. A pre-contoured distal locking plate was used for the distal tibial reconstruction. Secondary surgical procedures e.g. 2nd look, delayed primary closure, or skin grafting were necessary in 3 cases. The fibula was plated in 60% of cases. Four patients developed wound infections requiring antibiotics, and all resolved. The commonest rehabilitation regime was 6 weeks non weight bearing in plaster. Mean time to union was 18 weeks. There were 3 cases of delayed union, requiring bone grafting. One patient required removal of the plate due to local irritation, and one required a broken screw to be removed. Mean range of movement was 10 degrees dorsiflexion, 30 plantarflexion. The mean normalised AAOS foot and ankle core score was 41 (SD +/− 8). We conclude that MIPO fixation of distal tibial fractures is a safe and effective method of treatment. Functional outcome does not significantly differ from that of the general population.
The aim of this retrospective study is to assess the functional and radiological outcome of a multi-planar corrective osteotomy, distraction and locking fixed angle volar plate as the standard of treatment of distal radius mal-unions that require multi-planar correction. We conducted a retrospective study on 13 consecutive patients – 4 males, 9 females (mean age 49). All patients underwent volar approach, open wedge distraction osteotomy locking fixed angle volar plate and cancellous bone grafting Radiographic measurements and functional assessments were taken preoperatively, 3, 6 months and one year.Objective
Methods
We present the results of a bi-centre, retrospective study examining the clinical, functional and radiological outcomes of distal radius fracture fixation with the Aptus locking plates and Tri-Lock® variable angle locking screws. We assessed 61 patients with distal radius fractures with a minimum of six months follow-up. Functional assessment was made using the DASH score. We measured wrist range of movement and grip strength, and reviewed radiographs to assess restoration of anatomy, fracture union and complications. All fractures united within six weeks. Mean ranges of movement and grip strength were only mildly restricted compared to the normal wrist. The mean DASH score was 18.2. Seven patients had screws misplaced outside the distal radius although 3 of these remained asymptomatic. Five other patients developed minor complications. Variable angle locking systems benefit from flexibility of implant positioning and may allow enhanced inter-fragmentary reduction for accurate fixation of intra-articular fractures. However, variable-angle systems may lead to increased rates of screw misplacement.
Symptomatic neglected and displaced three- and four-part proximal humeral fractures are often difficult to reconstruct. Replacement has been reported to give poor functional outcome and hence is not the ideal treatment option. We report our results of secondary reconstruction of these difficult fractures with a locking plate system. Between 2003 and 2005, 15 healthy active patients with displaced three- to four-part fractures underwent revision/secondary open reduction and internal fixation with a locking plate system (Philos, Stratec UK Ltd). Ten patients had delayed presentation. Three patients had failed previous internal fixation. One patient had non-union and one had malunited fracture. Their average age was 63 years. Objective assessment was measured by the Constant score, subjective assessment by the Oxford questionnaire. The mean follow-up was 14 months.Introduction
Material and methods
A finite element study was carried out to compare the performance of a three-hole locking plate with angled screws to the ‘gold-standard’ four-hole hip plate. Two cases of the three-hole hip plate were examined; (a) three screws and (b) two screws (most proximal and most distal). A 3D model of the proximal femur was constructed from CT scans. A 3D CAD model of the four-hole hip plate was also created. The three-hole hip plate was then created from the four-hole implant in a way that it was possible to switch between all three models by activating/deactivating sections and/or switching material properties. A single common finite element model was generated, and a static analysis of each model variation was then performed in two steps using ABAQUS/standard. In the first, screws were pre-tensioned up to 150N. In the second, loads corresponding to stair climbing were applied. Forces in the screws, permitted to change in the second step, were examined and compared. Maximum principal stresses in the bone were also examined, with a focus on the stresses in the bone at the end of the plate in each model. The highest tensile force was in the proximal screw of the three-hole plate with three screws, followed by the most distal screw in the standard four-hole plate. This suggests that the risk of screw pull-out is highest at the proximal screw of the three-hole hip plate with three screws. A comparison of the forces in the distal screws for all cases shows that the highest tensile force was in the four-hole plate, followed by the three-hole plate with two screws. The lowest was the three-hole plate with three screws, which was in compression at full load. The maximum tensile stresses in the bone at the end of the plate were greatest for the standard four-hole hip plate, followed by the three-hole plate with two screws and then the three-hole plate with three screws. This indicates that the risk of bone fracture at the end of the plate is lowest for the three-hole hip plate with three screws. The risk of bone fracture is significantly lower for the three-hole hip plate, with either two or three screws, compared to the ‘gold-standard’ four-hole hip plate. This is partially offset by a small increase in the risk of screw pull out (in the proximal rather than the distal screw).
Despite the variety of implants or techniques that exist to treat displaced distal radial fractures, the majority fail to provide sufficient stability to permit early functional recovery. However, locking plates have the advantage over other implants in that locking screws add considerably to the overall stability. The aim of this study was to assess the functional outcome of patients with displaced distal radial fractures treated with a volar distal radial locking plate (Synthes). During a two year period, details of 98 patients admitted to our unit with inherently unstable dorsally displaced distal radial fractures treated with volar locking plates were collected prospectively. For the purpose of this analysis, only those patients (55) with unilateral fracture, able to attend the study clinic at 6 months post-injury were considered. Patients were immobilised in wool and crepe for a 2 week period. The group consisted of 15 males and 40 females with an average age of 54 (28 to 83). At 6 months, patients' perceived functional recovery averaged 80%. Objective assessment was considered in relation to the uninjured side: grip strength 73%; pinch strength 83%; palmarflexion 77%, dorsiflexion 80%; radial deviation 74%; ulnar deviation 74%; pronation 93%, and supination 92%. Seven patients complained of symptoms relating to prominent metalwork. Good/excellent early subjective and objective functional recovery was made following open reduction and internal fixation using volar locking plates of dorsally displaced distal radial fractures. We suggest that objective assessment of grip strength and dorsiflexion can be used as a measure of patient perception of function.