Introduction: The time necessary to return to sports activities after ACL reconstruction is 6 months. Few authors have speculated on the possibility to reduce this time with accelerated rehabilitation. But nobody has considered the proprioceptive aspects. Recently some experiments have demonstrated that a perturbation training program can improve the functional stability in ACL injured and reconstructed knees. Nevertheless there are no studies showing the effects of these exercises in long period. The aim of this study was to find out if a specific proprioceptive exercise as perturbation training permits a further and durable recovery of proprioception after ACL reconstruction for an early return to agonism. Material and Methods: 70 sportsmen with an isolated ACL injury were recruited. They were undergone to arthroscopic ACL reconstruction with the ST+G tendons by the same team. At discharge they were randomly assigned to two homogeneous groups: the first one ‘self-controlled’ composed by patients that followed the standard rehabilitation protocol without any help of therapist; the second group ‘Perturbation’ constituted by patients that followed between the 2nd and the 3rd months a specific proprioceptive protocol that included perturbation exercises on support surfaces (perturbation training). They have been clinically evaluated before surgery and after 2, 3, 6 and 12 months after surgery with a kinaesthetic device constituted by a tilting platform equipped by digitalized sensor connected to a computer. The protocol included three repetition of one and two legged standing balance. The statistical analyses with t-test considered significant value of p< 0.05. Results: All the test shows a significant improvement between pre and post-operative values. The improvements in the Perturbation group are more significant than the ones in the ‘self-controlled’ group at the 3rd month (two legged stance test: p=0,001; one legged stance on the operated side: p=0,003; one legged stance on the healthy side: p=0,0001). Best results in the Perturbation group are maintained at the 6th month only in the one legged stance on healthy side (p=0,014) but any difference is still present at 12 months. Conclusion: The significant improvement of the Perturbation group’s values at 3rd month demonstrates that accelerated rehabilitation of proprioception after ACL reconstruction may enhance knee proprioception and suggests the possibility of an early return to sports activities. Nevertheless it must be considered the duration of benefits obtained is limited to the period of application. Therefore other studies are necessary to establish if it’s only a problem of time and duration of application and/or type of specific rehabilitative exercises

There has been very little documented regarding the impact of meniscal injuries on knee proprioception. The aim of this study was to investigate the proprioceptive function of patients with meniscal tears and asses the influence that arthroscopic partial menisectomy has on knee proprioception. One hundred subjects were recruited comprising an Arthroscopy group (50 patients) and a Normal Control group (50 subjects). The Biodex Balance SD System was used to assess proprioception. This equipment measures knee proprioception on an electronic platform. The balance of the subject is computed producing an Overall Stability Index (OSI). Lower scores reflect better proprioception. Knee stability was assessed clinically and with the Rolimeter knee arthrometer. The Lysholm and IKDC scoring systems were used to evaluate all the subjects. Of the 50 subjects within the Arthroscopy group (all of whom had a normal ACL confirmed) 34 were found to have meniscal tears. Twenty-nine of the 34 patients with meniscal tears returned for their follow-up review 3 months post-operatively. The proprioceptive function of the injured knee of the Arthroscopy group with meniscal tears (mean OSI 0.86) was significantly poorer compared to that of their uninjured knee (mean OSI 0.62, p< 0.001, 95%CI 0.14, 0.34) and to the Normal Control group (mean OSI 0.49, p< 0.001, 95%CI 0.21, 0.54). There was no significant improvement in their proprioceptive function following menisectomy (mean OSI 0.75, p=0.23, 95%CI −0.07, 0.28). There was a significant improvement of both the Lysholm (p=0.004) and IKDC (p=0.021) scores postoperatively. Conclusion: These results indicate that there is a demonstrable proprioceptive deficit in patients with meniscal tears even in the presence of a normal ACL. This deficiency in proprioception did not improve within three months following arthroscopic partial menisectomy despite the improvement in functional outcome measures

Purpose of Study. To investigate the proprioceptive function of patients with an ACL rupture before and after reconstruction and correlate these findings with ligament laxity testing and clinical outcome measures. Summary of Methods and Results. Fifty patients with an ACL rupture and 50 normal controls were recruited to the study. The Biodex Balance SD System was used to assess knee proprioception. This equipment measures proprioceptive function using an electronic platform. The balance of the subject is computed using stabilometry and an Overall Stability Index (OSI) is produced. A lower score reflects better proprioception. Knee stability was assessed clinically and with the Rolimeter knee arthrometer in all subjects. Participants were evaluated using the Tegner, Lysholm, Cincinnati and IKDC scoring systems. In the ACL group, 34 patients underwent ACL reconstruction and returned for their follow-up review 3 months post-operatively. The proprioceptive function of the injured knee of the ACL group (mean OSI 0.70) was significantly poorer compared to that of their uninjured knee (mean OSI 0.46, p<0.001, 95%CI 0.14, 0.34) and to the Normal Control group (mean OSI 0.49, p=0.01, 95%CI 0.05, 0.38). There was a significant improvement in proprioception of the injured knee following ACL reconstruction (mean OSI 0.47, p=0.003, 95%CI 0.10, 0.42). A significant correlation was found between pre-operative proprioception measurements and all the pre-operative knee outcome scores, however this correlation was not found post-operatively. No correlation was found between ligament laxity testing and either proprioception measurements or knee outcome scores. Conclusion. Patients with ACL ruptures were found to have a proprioceptive deficit which improved following reconstruction, the measurements of which correlated better with clinical outcome scores than instrumented ligament laxity testing

Aim: To assess shoulder proprioception before and after a new surgical treatment for multi-directional instability. Methods: A pilot study assessing shoulder proprioception in asymptomatic controls (n=6), pre-operative patients (n=7) awaiting surgery for multidirectional instability (having failed rehabilitation) and post-operative patients (n=7) having undergone thermo-capsular shrinkage and rehabilitation. Data were obtained using the Proprioception Assessment System developed at our centre following a standardised protocol to record threshold to detection of passive movement (TTDPM) and reproduction of passive position (RPP) in three positions of rotation. Results: For controls, TTDPM at 0 degrees, +30 degrees and −30 degrees was 1.08 degrees ± 1.05 degrees, 1.75 degrees ± 1.80 degrees and 1.61 degrees ± 1.68 degrees respectively. In the pre-operative group the asymptomatic shoulders had values of 2.48 degrees ± 2.22 degrees, 2.14 degrees ± 1.59 degrees and 1.51 degrees ± 0.87degrees and the symptomatic shoulders 8.59 degrees ± 12.96 degrees, 6.89 degrees ± 6.36 degrees and 4.4 degrees ± 3.45 degrees respectively. In the post-operative group, asymptomatic shoulders had values of 2.09 degrees ± 1.25 degrees, 2.31 degrees ± 1.30 degrees and 2.30 degrees ± 1.31 degrees and symptomatic shoulders 2.15 degrees ± 1.30 degrees, 2.54 degrees ± 1.43 degrees and 2.89 degrees ± 2.12 degrees respectively. With respect to RPP, controls had values at 0 degrees, +30 degrees and –30 degrees of 2.49 degrees ± 1.02 degrees, 2.58 degrees ± 1.13degrees and 2.72 degrees ± 2.11 degrees. In the pre-operative group, the results for asymptomatic shoulders were 2.48 degrees ± 0.68 degrees, 0.87 degrees ± 0.51 degrees and 3.44 degrees ± 2.41 degrees and for symptomatic shoulders 5.63 degrees ± 2.05 degrees, 3.17 degrees ± 2.05 degrees and 7.56 degrees ± 6.10 degrees respectively. In the post-operative group, the results for asymptomatic shoulders were 2.85 degrees ± 1.13 degrees, 3.78 degrees ± 1.94 degrees and 2.55 degrees ± 2.11 degrees and for symptomatic shoulders 2.28 degrees ± 0.81 degrees, 5.40 degrees ± 5.91 degrees and 3.62 degrees ± 1.63 degrees respectively. Conclusions: There were no differences between shoulders in controls and post-operative patients. Despite the small numbers, the pre-operative patients showed significant differences (p< 0.05) between shoulders in two of the six test protocols. Post-operative shoulders had means similar to controls suggesting thermo-capsular shrinkage may help regain shoulder proprioception after injuries

Aims: The purpose of this study, we need to identify the balance whether is influenced by proprioception or not? Can those be used as objective measures to predict functional stability?. Materials & Methods: Twelve young adults (10 males; 2 females) with chronic ACL deficiency (6 R’t knee; 4 L’t knee) were included this test (average time from injured to test: 12.8 months). The control group was 13 normal individuals (11 males; 2 females). There were no associated injuries in both group and no significant difference about age, height and body weight. Both groups were tested on computerized balance-testing machine system (self-design), proprioception testing apparatus (self-design) and the Isokinetic Dynamometer (Con-Trex Multi Joint System, Switzerland). Results: In ACL group, the Lachman score showed 67.7 ± 4.2 points. The difference of joint laxity between injured and uninjured knee was 9± 2 vs 3.7 ± 1.2 using K-T 1000 arthrometer. In single leg hopping test, showed significant difference (p< 0.05) between injured and uninjured leg. In proppriocetion test, the results showed significant time-delay in both TTDPM and RPP in injured knee. The results of balance test showed control group that had better tilting and unsteadiness than ACL group (P< 0.05). Correlation of TTDPM and mean tilting measurement showed significant difference (r=0.52, P< 0.05, y=0.6075x – 0.2072). There was lower correlation between RPP and mean tilting (r=0.19, p> 0.05). There was poor correlation between muscle force and mean tilting (extensor: r=0.20; flexor: r=0.22; p> 0.05). Similarly, time from injury to test correlated poorly with both proprioception (TTDPM: r=0.02; RPP: r=0.132) and balance (mean tilting: r=0.06; unsteadiness: r=0.004). Conclusion: Loss of proprioceptive sensibility had been proved by authors study, it was rarely indicated balance function in the ACL deficiency. In our study, we had proved positive correlation between proprioception and balance. We do believe poor proproception may cause of imbalance after rupture of ACL. In future rehabilitative program, balance training must be aided for restoration and recreation the proproceptive ability around knee joint

Introduction: Functional Foot Orthoses (FFO’s) have been shown to improve one element of balance, postural sway, when prescribed for patients with ankle injuries. Little is known, however, about the effect of these devices on ankle stability/proprioception, or the changes which might occur as the patient becomes habituated to using the device. We studied these effects from the time of initial application of the FFO through to regular usage at six weeks. Methods: Patients with musculoskeletal conditions affecting the lower limb that required custom made FFO’s were evaluated. A standardised protocol, using the Biodex stability system (a balance platform), to assess several stability indices was performed. Patients were assessed before fitting the orthosis, at the time of fitting and six weeks later. The American Orthopaedic Foot and ankle Society (AOFAS) score was also used to evaluate the progress of these patients. Results: There were 13 male and seven female patients, aged 10 to 64 years. Patients had a range of orthopaedic conditions and all been assessed by orthopaedic specialist and podiatrist as having correctable foot biomechanics. In 6 patients, proprioception deteriorated on initial application of FFO’s. However, all patients exhibited improved over-all stability by a mean of 2.5 points (Normal range 0.82–3.35) at 6 weeks evaluation. The mean AOFAS on presentation was 72 and the final mean score was 97, both of which were clinically and statistically significant (t test, p< 0.05). Eighteen patients had complete resolution of symptoms of pain and instability. Conclusions: FFO’s alter foot biomechanics, and in doing so appear also to improve balance and proprioception. Proprioception deteriorated in 30% of cases on initial application of orthotics, but pain and instability improved in more than 90% of patients on extended use of foot orthotics, with this improvement becoming manifest by 6 weeks after starting use of the device

The aimof this study was to assess proprioception in multi-directional instability of the shoulder before and after a new surgical treatment. A cross-sectional pilot study assessing shoulder proprioception in asymptomatic controls (n=6), pre-operative patients (n=7) awaiting surgery for atraumatic, multidirectional instability having failed a comprehensive rehabilitation programme and post-operative patients (n=7) having undergone thermo-capsular shrinkage of the shoulder and post-operative rehabilitation. Data were obtained using the Proprioception Assessment System developed at this centre following a standardised protocol to record both threshold to detection of passive movement (TTDPM) and reproduction of passive position (RPP) in three positions of rotation. Means and standard deviations are presented. There were no differences between shoulders in controls and post-operative patients. Despite the small numbers, pre-operative patients showed significant differences (p< 0.05) between shoulders in 2 of the 6 test protocols. Post-operative shoulders had means similar to controls suggesting thermo-capsular shrinkage may help regain shoulder proprioception after injury

Proprioception protects joints against injurious movements and is critical for joint stability maintenance under dynamic conditions. Knee replacement effect on proprioception in general remains elusive. This study aimed to evaluate the changes in proprioceptive performance after knee replacement; comparing Total (TKA) to Unicompartmental Knee Arthroplasty (UKA). Thirty-four patients with osteoarthritis were recruited; 15 patients underwent TKA using the AGC prosthesis and 19patients underwent UKA using the Oxford prosthesis. Both cruciate ligaments were preserved in the UKA group, while only the PCL was preserved in TKA patients. Patients’ age was similar in both groups.> Joint Position Sense (JPS) and postural sway were used as measures of proprioception. Both groups were assessed pre- and 6 months post-operatively in both limbs. JPS was measured as the error in actively and passively reproducing five randomly ordered knee flexion angles between 30 and 70°using an isokinetic dynamometer. Postural sway (area and path) was measured during single leg stance using a Balance Performance Monitor. Functional outcome was assessed using the Oxford Knee Score (OKS). Pre-operatively, no differences in JPS or sway were found between limbs in either group. No differences existed between the two groups. Post-operatively, both groups had significant improvement of JPS in the operated limb (UKA mean4.64°, SD1.44° and TKA mean5.18°, SD1.35°). No changes in JPS were seen in the control side. A significant improvement (P< 0.0001) in sway area and path was found in the UKA group only in both limbs. No significant changes in sway occurred in either limb of TKA patients. The OKS improved from 21.4 to 35.5 for TKA patients and from 23.9 to 38for UKA patients. Both UKA and TKA improve proprioception as assessed by JPS. However, UKA alone improves postural sway in both limbs. This may impart explain why UKA patients function better than TKA patients

Introduction: ACL injury is very common among sport activities. The incidence is very high and causes an important disorder in the articular function. Some articles have been published in the recent years about the risks to suffer this injury and its consequences in the biomechanics and proprioception of the limb. Although most of them were performed in animals and cadaver specimens and a few of them were realized in patients for a dynamic evaluation. Purpose: The objective was to analyze in a longitudinal and prospective manner the changes in proprioception (muscular latency in the muscles span the knee in front of a stimulus load) occurred in the joint in 25 patients undergone an ACL injury before and after ACL reconstruction using the contra lateral knee as control. Material and Methods: The study was performed in an experimental task pre and 4 and 6 months post surgery. Clinical Tegner, Lysholm, IKDC and SF12 evaluation, motion analysis system (EliteR) and surface electromyography was performed in a synchronized manner during a single leg jump before and after a fatigue exercise of a 10 seconds repetitive single leg jump. The muscles studied were anterior rectus, lateral and medial vastus, semitendinous and femoral biceps of both knees. Statistical analysis was performed and a P value < 0.05 was considered significant. Results: Statistical significant larger latency times in each muscle but lateral vastus was observed in the affected knee in the preoperative period with improvement in the first period of 4 months postoperatively reaching measures of the normal contralateral knee without further improvement at the 6 month period. Vastus medialis was the muscle more affected before surgery and semitendinous, although improved, never reached a normal reactivity. Extensor muscles of the normal knee presented in all the periods of the study similar results but flexor muscles showed significant better propioceptive function in the 4th and 6th month post surgery. Improvement in latency time of muscle reactivity correlated with better scores in the Lysholm, IKDC and SF12 scores, although the SF12 mental status didn’t change. Conclusion: Operated knees improve their neuromuscular activity relatively fast during the first 4th months. Therefore, specifically talking about neuromuscular function normal physical activity may be can be allowed at the 4th month and that means two months before usually normal activity level is permitted. Preoperative rehabilitation would have to insist to get better medialis vastus function. The mental status didn’t correlate with the neuromuscular status that means that psychologic aspects must be treated simultaneously with the physical training. Synergy among neurological pathways would exist, appreciating improved response in flexor muscles in the contralateral knee during the rehabilitation period

To investigate whether the harvesting of Hamstring graft in ACL reconstruction results in compromised knee flexion strength and proprioception, and hence knee function?, a prospective study, approved by the local Ethics Committee, to assess the function and strength of the knee joint in patients who had ACL reconstruction done using a four-strand Hamstring graft. The control group was the contra lateral knees. 28 knee joints were studied with mean follow-up of 70.1 weeks (52–156). All operated knees received an extensive set regime of pre-and post-operative physiotherapy. Assessment tools were clinical examination, Laxometer arthrometry for measured anterior draw, Biodex dynamometry and Stabilometry for Hamstring and quadriceps strength and proprioception. The knee function was assessed using a questionnaire incorporating IKDC (International knee documentation committee) performa, Lysholm 2 score, Tegner’s activity scale and Oxford knee score. Following reconstruction (mean 70.1 weeks postop), objective assessment using Biodex dynamometer showed that mean peak flexion torque around the knee joint was 69.8 N-m and 76.2 N-m in the operated and non-operated knee respectively. There was no difference in flexion torque in both groups. Mean Flexion: Extension ratio around the knee joint was 53.9% in the operated and 53.2% in non-operated sides. Mean stability index, measured using open eye stabilometry, was 3.5 (SD 2.4) in the operated side and 3.1 (SD1.8) in the non-operated side, with no significant difference demonstrable (p< 0.05). The mean age of patients was 28.3 years (18–44). Mean IKDC score following reconstruction was 74.8 (49–100), SD18.5. Mean Tegner’s activity scale improved from 2.5(3–7) pre-operative to post-operative 5.4(3–7), p< 0.01. Mean Lysholm 2 score improved from 53.4(41–76) pre-operatively to 85(64–100) post-operatively, p< 0.01. Subjective function of the knee on a scale of 0–10 improved from pre-operative 3.1 to post-operative 7.7 (p< 0.01). Arthrometry at 25-degree flexion and 130 N force using Laxometer showed mean anterior laxity 5.3mm on the operated side and 3.1 on the healthy side (side to side difference 2.2mm). Conclusion: The function of the knee improved significantly following ACL reconstruction both objectively and subjectively. The harvesting of Hamstring as a graft neither compromises the flexion torque nor the proprioception around the knee joint

Aims: Whether the harvesting of Hamstring graft for ACL reconstruction results in compromised knee flexion strength and proprioception, and hence knee function?. Methods: A prospective study, approved by the local Ethics committee, was undertaken to assess the function and strength of the knee joint in patients who had ACL reconstruction performed using a four-strand Hamstring graft. The contra lateral knee acted as control. 28 knee joints were studied with mean follow up 70.1 weeks (range 52–156). All operated knees received an extensive set regime of pre and post-operative physiotherapy. Assessment tools were Biodex dynamometry and stabilometery for hamstring and quadriceps strength and proprioception, clinical examination, Laxometer arthrometry for measured anterior draw. The knee function was assessed using a questionnaire incorporating International knee documentation committee (IKDC) proforma, Lysholm 2 score and Tegner’s activity scale. Results: Objective assessment using Biodex dynamometer pre-operatively showed that mean peak flexion torque was 67.86 N-m (SD± 24) in the involved knee and 76.1 N-m (SD± 22.2) in the healthy knee. Following reconstruction (mean 70.1 weeks post-op), mean peak flexion torque around the knee joint was 69.8 N-m (SD± 20.6) and 76.2 N-m (SD ±22.1) in the operated and non-operated knee (control) respectively. Flexion torque in the operated knee was as good as the control and not significantly different from the pre-operative levels. Mean Flexion: Extension ratio around the knee joint was 53.9% in the operated and 53.2% in non-operated sides. Mean stability index, measured using open eye stabilometery, was 3.5 (SD±2.4) on the operated and 3.1 (SD±1.8) on the non-operated side, with no significant difference demonstrable. The mean age of patients was 28.3 (range 18–44) years. Mean IKDC score following reconstruction was 74.8 (range 49–100), SD±18.5. There was significant improvement in pre and post reconstruction mean Lysholm 2 and Tegner’s activity scores (p< 0.01). Subjective function of the knee on a scale of 0–10 improved from pre-operative 3.1 to post-operative 7.7 (p< 0.01). Arthrometry at 25-degree flexion and 130 N force using Laxometer showed mean anterior laxity 5.3mm on the operated side and 3.1 on the healthy side (side to side difference 2.2mm). Conclusion: The function of the knee improved significantly following ACL reconstruction both objectively and subjectively. The harvesting of Hamstring as a graft neither compromises the flexion torque nor the proprioception around the knee joint

Deterioration in knee joint proprioception has been postulated to occur following injury, resulting in further instability due to disruption of receptors and feedback mechanisms. Surgical reconstruction techniques may also influence post-operative proprioceptive ability (PA). We hypothesised that anterior cruciate ligament (ACL) reconstruction techniques which disrupt the knee capsule would result in a decrease in PA. Following ethical approval, a total of 48 subjects (mean age: 28.1 ± 10.5, 34 male, 14 female) undergoing ACL reconstruction surgery were included in the study. Fifteen subjects underwent “open” capsule ACL surgery and patellar tendon graft, whereas 33 subjects had “closed” capsule surgery with a hamstring tendon graft. Knee proprioception was measured on a custom-designed test apparatus incorporating electromagnetic position sensors (Polhemus Fastrack) located on femoral and tibial landmarks to accurately track knee angle during flexion-extension (no load). Leg flexion-extension under partial weight-bearing (5kg) was also evaluated. Pre-operative PA was assessed bilaterally, and then again on operated joints at three, six and twelve months post-op. Proprioceptive ability was measured as the cumulative absolute error in knee angle (°) between five repeat measurements and a target angle. We observed no significant difference in PA between injured and contralateral knees prior to ACL reconstruction. Post-operatively, no significant difference in PA was observed between “open” versus “closed” ACL techniques, irrespective of loading conditions. While trends indicated that PA during knee extension (no load) and leg flexion (partial weight-bearing) improved over the 12 months compared to pre-operative values in closed ACL surgery, these were not significantly different to open ACL results. The proportion of subjects whose PA improved in at least two out of the three post-op evaluations was also similar (approx 50%) across all groups, irrespective of joint loading. The only difference was PA during leg flexion under partial weight bearing, where 27% of open ACL surgery patients showed improvement in two or more follow-up tests, as opposed to 58% of closed ACL surgery patients. We present a method to determine pre- and postoperative PA during knee flexion/extension under no load as well as under partial weight-bearing. We saw no significant difference in PA of the knee under no-load versus load. We also saw no significant difference in postoperative PA following open capsule, patellar tendon graft versus closed capsule, hamstring tendon graft ACL reconstruction technique after 1 year follow-up

Aim: To investigate and compare the effects of two types of LCS total knee arthroplasty on joint proprioception and range of motion. Methods: 47 patients were randomised to receive either a LCS AP glide or Rotating platform prosthesis. Clinical scores (Oxford knee score, American knee society score, EuroQol), range of motion and proprioception were assessed prior to and at 3,6, and 12 months after the operation. Proprioception was assessed in terms of absolute error angle (mean difference between the target angle and the response angle). Knee angles were measured in degrees using an electromagnetic tracking device, Polhemus 3Space Fastrak that detected positions of sensors placed on the test limb. Student’s t-test was used to compare the mean of two groups (with a level of significance of p < 0.05). Results: Both groups were comparable in terms of pre-operative range of motion, oxford knee score, American knee society score, EuroQol score and proprioception. There was statistically significant improvement in the Oxford knee score, AKSS and EuroQol score in both groups (p< 0.001), but there was no difference between the groups with respect to these parameters. There was improvement in the proprioception (reduction in absolute error angle) in both groups though this was not significant statistically (p> 0.05). Conclusions: We did not find significant difference between AP glide and RP LCS knee arthroplasty in terms of improvement in proprioception and range of motion

Orthopedic surgeons are taught to remove the under surface of the patella in accordance with the thickness of polyethylene used to replace an equivalent amount of bone. Inability, however, to obtain a symmetrical removal of bone can lead to subluxation, increased tension producing pain, and affect range of motion. A convenient and fast way to recognise this asymmetry and remove an additional sliver of bone from the patella would be an advantage in creating a patella of even thickness. Eight orthopedic surgeons were asked to evaluate 24 pre-cut patellar specimens with varying asymmetric thicknesses in a bag without visualisation. By feeling the patella between the thumb and forefinger, they were instructed to identify the thickest portion of the patella as well as to determine the difference in thickness between the thinnest and thickest sides. Two trials were conducted with each orthopedic surgeon consecutively. Orthopedic surgeons were able to determine through proprioception the thickest one-half of the patella 91% of the time. This did correlate with experience in total knee arthroplasty. They were able to differentiate a 1 mm difference in patellar asymmetry 36% of the time, a 2 mm difference 61% of the time, and a 3 mm difference 81% of the time. Orthopedic surgeons can identify an asymmetrically cut patella by assessing thickness of the patella between their thumb and forefinger the majority of the time. By doing this technique, inadvertent asymmetrically thick patellas at the time of total joint arthroplasty can be min-imised. This technique should be incorporated into the standard regimen of performing total knee arthroplasties

Aim: To investigate and compare the effects of two types of LCS total knee arthroplasty AP glide {(posterior cruciate is retained and the mobile bearing allows anteroposterior and well as rotational movement) and RP (in which posterior cruciate is sacrificed and the mobile bearing allows only rotational movement)} on joint proprioception and range of motion. Methods: 30 patients scheduled to undergo mobile bearing total knee arthroplasty were randomised to receive either a LCS AP glide or Rotating platform prosthesis. Clinical scores (Oxford knee score, American knee society score (AKSS), EuroQol), range of motion and proprioception were assessed prior to and at three and six months after the operation. Proprioception was assessed in terms of absolute error angle (mean difference between the target angle and the response angle). Student’s t-test was used to compare the mean of two groups (with a level of significance of p < 0.05). Results: Both groups were comparable in terms of pre-operative range of motion, oxford knee score, American knee society score, EuroQol score and proprioception. At 6 months there was significant improvement in the Oxford knee score, AKSS and EuroQol score in both groups (p< 0.001), but no difference was noted between the two groups with respect to these parameters. There was improvement in the proprioception (reduction in absolute error angle) in both groups though this was not significant statistically (p> 0.05). The mean active non-weight-bearing range of motion improved in both groups {AP glide group, (p< 0.05) and RP group, (p> 0.05)}. Conclusions: We did not find significant difference between AP glide and RP LCS knee arthroplasty in terms of improvement in proprioception and range of motion

Purpose of the study Function is strongly infl uenced by proprioceptive ability, this prospective longitudinal study aimed to evaluate the change in proprioceptive performance after knee replacement; comparing total to unicompartment replacement. Methods and Results Two groups of patients with OA as diagnosed clinically and by X-ray were recruited. Group 1 consisted of 15 patients (mean age 65.8yrs range 57-72yrs, 10 females & 5 males) listed for Total Knee Arthroplasty (TKA) with the AGC (Biomet, UK). Group 2 consisted of 19 patients (mean age 65.5yrs range 52–75yrs; 9 females & 10 males) listed for Oxford Uni-compartmental Knee Arthroplasty (OUKA) for medial compartment OA. The ACL and PCL were present and preserved in all patients in Group 2, while only the PCL was preserved for Group 1 patients. Joint Position Sense (JPS) & sway were used as measures of proprioception performance. Both groups were assessed pre- and 6 months post-op. JPS was measured using an isokinetic dynamometer (KinCom, Chatanooga Ltd) as the error in actively and passively reproducing fi ve randomly ordered knee fl exion angles (30°, 40°, 50°, 60° and 70°). Sway (area, path and velocity) was measured during single leg stance using a Balance Performance Monitor (SMS Medical) for 30-second interval. Functional outcome was assessed using the Oxford Knee Score (OKS). Pre-operatively, no differences in JPS or sway were found between limbs in either group. No differences existed between the two groups. Post-operatively, both groups had signifi cant improvement of JPS in the operated limb only (Mean ± standard deviation for UKA 4.64±1.44° and for TKA 5.18±1.35°). No changes in JPS were seen in the control side. Group 2 patients showed signifi cant improvement in both sway area and path (p< .0001) for both limbs post-operatively. No signifi cant post-operative changes in sway occurred in either limb of Group 1 patients. The OKS improved post-operatively in both groups, rising from 21.4 to 35.5 for Group 1 patients and from 23.9 to 38 for Group 2 patients. Conclusion Interestingly, joint position sense improved for both groups but did not seem to show any difference between UKA and TKA. Postural sway was infl uenced by joint replacement type. Ligament retention may contribute to improved global postural control seen after unicompartmental knee arthroplasty and may explain the higher level of function seen in these patients

Introduction: Knee joint arthroplasty (total or unicompartmental) is the standard operative treatment for osteoarthritis (OA). Survival rate is good for both types but functional outcome is different. The function of unicompartmental knee arthroplasty (UKA) is substantially better than that of total knee arthroplasty (TKA). As function can be strongly influenced by proprioceptive ability, it is possible that improved outcome seen in patients with UKA results from retaining proprioceptive function associated with the cruciate ligaments. This prospective longitudinal study aimed to evaluate the change in proprioceptive performance after knee replacement; comparing TKA to UKA. Methods and Materials: Two groups of patients with OA as diagnosed clinically and by X-ray were recruited. Group 1 consisted of 15 patients (mean age 65.8 years range 57–72 years, 10 females and 5 males) listed for TKA with the AGC prosthesis (Biomet, UK). Group 2 consisted of 19 patients (mean age 65.5 years range 52–75 years; 9 females and 10 males) listed for UKA with the Oxford UKA (Biomet, UK) for medial compartment OA. The ACL and PCL were present and preserved in all patients in Group 2, while only the PCL was preserved in Group 1 patients. Joint Position Sense (JPS) and postural sway were used as measures of proprioception performance. Both groups were assessed pre-and 6 months post-operatively in both limbs. JPS was measured using a dynamometer (KinCom, Chatanooga Ltd) as the error in actively and passively reproducing five randomly ordered knee flexion angles (30°, 40°, 50°, 60° and 70°). Postural sway (area, path and velocity) was measured during single leg stance using a Balance Performance Monitor (SMS Medical) for 30 seconds interval. Functional outcome was assessed using the Oxford Knee Score (OKS). Results: Pre-operatively, no differences in JPS or sway were found between limbs in either group. No differences existed between the two groups. Post-operatively, both groups had significant improvement of JPS in the operated limb only (Mean ± standard deviation for UKA 4.64±1.44° and for TKA 5.18±1.35°). No changes in JPS were seen in the control side. An improvement in sway was found in the UKA group only. UKA patients showed significant improvement in both sway area and path (p< .0001) for both limbs post-operatively. No significant post-operative changes in sway occurred in either limb of TKA patients. The OKS improved postoperatively in both groups, rising from 21.4 to 35.5 for TKA patients and from 23.9 to 38 for UKA patients. Conclusion: Interestingly, joint position sense improved for both groups but did not seem to show any difference between UKA and TKA. Postural sway was influenced by joint replacement type. Ligament retention may contribute to improved global postural control seen after unicompartmental knee arthroplasty and may explain the higher level of function seen in these patients

Osteoarthritis (OA) is a common cause of chronic pain. Subchondral bone is highly innervated, and bone structural changes directly correlate with pain in OA. Mechanisms underlying skeletal–neural interactions are under-investigated. Bone derived axon guidance molecules are known to regulate bone remodelling. Such signals in the nervous system regulate neural plasticity, branching and neural inflammation. Perturbation of these signals during OA disease progression may disrupt sensory afferents activity, affecting tissue integrity, nociception, and proprioception. Osteocyte mechanical loading and IL-6 stimulation alters axon guidance signalling influencing innervation, proprioception, and nociception. Human Y201 MSC cells, embedded in 3D type I collagen gels (0.05 × 106 cell/gel) in 48 well plastic or silicone (load) plates, were differentiated to osteocytes for 7 days before stimulation with IL-6 (5ng/ml) with soluble IL-6 receptor (sIL-6r (40ng/ml) or unstimulated (n=5/group), or mechanically loaded (5000 μstrain, 10Hz, 3000 cycles) or not loaded (n=5/group). RNA extracted 1hr and 24hrs post load was quantified by RNAseq whole transcriptome analysis (NovaSeq S1 flow cell 2 × 100bp PE reads and differentially expressed neurotransmitters identified (>2-fold change in DEseq2 analysis on normalised count data with FDR p<0.05). After 24 hours, extracted IL-6 stimulated RNA was quantified by RT-qPCR for neurotrophic factors using 2–∆∆Ct method (efficiency=94-106%) normalised to reference gene GAPDH (stability = 1.12 REfinder). Normally distributed data with homogenous variances was analysed by two-tailed t test. All detected axonal guidance genes were regulated by mechanical load. Axonal guidance genes were both down-regulated (Netrin1 0.16-fold, p=0.001; Sema3A 0.4-fold, p<0.001; SEMA3C (0.4-fold, p<0.001), and up-regulated (SLIT2 2.3-fold, p<0.001; CXCL12 5-fold, p<0.001; SEMA3B 13-fold, p<0.001; SEMA4F 2-fold, p<0.001) by mechanical load. IL6 and IL6sR stimulation upregulated SEMA3A (7-fold, p=0.01), its receptor Plexin1 (3-fold, p=0.03). Neutrophins analysed in IL6 stimulated RNA did not show regulation. Here we show osteocytes regulate multiple factors which may influence innervation, nociception, and proprioception upon inflammatory or mechanical insult. Future studies will establish how these factors may combine and affect nerve activity during OA disease progression

Aims. Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane. Methods. Postoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation. Results. Overall, 26/40 hips had a centre of rotation displaced posteriorly compared to the contralateral hip, increasing to 33/40 once corrected for sagittal tilt, with a mean posterior displacement of 7 mm. Linear regression analysis indicated that stem anteversion needed to be increased by 10.8° to recreate the head centre in the AP plane. Merely matching the native version would result in a 12 mm posterior displacement. Conclusion. This study demonstrates the significant incidence of posterior displacement of the head centre in uncemented hip arthroplasty. Effects of such displacement include a reduction in impingement free range of motion, potential alterations in muscle force vectors and lever arms, and impaired proprioception due to muscle fibre reorientation. Cite this article: Bone Joint Res 2022;11(3):180–188

Introduction. PIEZO mechanoreceptors are increasingly recognized to play critical roles in fundamental physiological processes like proprioception, touch, or tendon biomechanics. However, their gating mechanisms and downstream signaling are still not completely understood, mainly due to the lack of effective tools to probe these processes. Here, we developed new tailor-made nanoswitches enabling wireless targeted actuation on PIEZO1 by combining molecular imprinting concepts with magnetic systems. Method. Two epitopes from functionally relevant domains of PIEZO1 were rationally selected in silico and used as templates for synthesizing molecularly imprinted nanoparticles (MINPs). Highly-responsive superparamagnetic zinc-doped iron oxide nanoparticles were incorporated into MINPs to grant them magnetic responsiveness. Endothelial cells (ECs) and adipose tissue-derived stem cells (ASCs) incubated with each type of MINP were cultured under or without the application of cyclical magnetomechanical stimulation. Downstream effects of PIEZO1 actuation on cell mechanotransduction signaling and stem cell fate were screened by analyzing gene expression profiles. Result. Nanoswitches showed sub-nanomolar affinity for their respective epitope, binding PIEZO1-expressing ECs similarly to antibodies. Expression of genes downstream of PIEZO1 activity significantly changed after magnetomechanical stimulation, demonstrating that nanoswitches can transduce this stimulus directly to PIEZO1 mechanoreceptors. Moreover, this wireless actuation system proved effective for modulating the expression of genes related to musculoskeletal differentiation pathways in ASCs, with RNA-sequencing showing pronounced shifts in extracellular matrix organization, signal transduction, or collagen biosynthesis and modification. Importantly, targeting each epitope led to different signaling effects, implying distinct roles for each domain in the sophisticated function of these channels. Conclusion. This innovative wireless actuation technology provides a promising approach for dissecting PIEZO-mediated mechanobiology and suggests potential therapeutic applications targeting PIEZO1 in regenerative medicine for mechanosensitive tissues like tendon. Acknowledgements. EU's Horizon 2020 ERC under grant No. 772817 and Horizon Europe under grant No. 101069302; FCT/MCTES for PD/BD/143039/2018, COVID/BD/153025/2022, 10.54499/2020.03410.CEECIND/CP1600/CT0013, 10.54499/2022.05526.PTDC, 10.54499/UIDB/50026/2020, 10.54499/UIDP/50026/2020, and 10.54499/LA/P/0050/2020