Introduction

Patients with severe knee instability and extensive bone loss remain a surgical challenge. In such cases, regular knee implants and constrained condylar implants may not be suitable or have been attempted and failed.

Hinged knee replacements have developed an important role in the management of such complex knee cases. They also have an increasingly important role in cases such as rheumatoid arthritis and other cases of severe joint destruction.

We present a review of 138 consecutive hinge knee arthroplasties of 8 different Hinge models performed in our unit between 2004 and 2010.

Separation of the ACL into anteromedial (AM) and posterolateral (PL) fibre bundles has been widely accepted. The bundles act synergistically to restrain anterior laxity throughout knee flexion, with the PL bundle providing the more important restraint near extension and its obliquity better restraining tibial rotational laxity.

10% of ACL injuries involve isolated rupture to one of these bundles causing patients to present with instability symptoms or pain. As knowledge about the influence of the ACL bundles on knee kinematics has increased, isolated reconstruction of either PL or AM bundle has been advocated. However only one cohort study of 17 patients has been presented in the clinical literature.

KOOS (Knee Injury and Osteoarthritis Outcome Score) and IKDC (International Knee Documentation Committee Form) scores at 1yr post op were obtained for 12 patients who had undergone isolated ACL augmentation between 2007 and 2009. These were compared with previously published outcome scores for standard ACL reconstruction procedures. In addition examination under anaesthesia (EUA) assessments were analysed to see if a pattern of laxity for isolated AM and PL rupture could be determined.

There were 5 patients with isolated AM bundle rupture and 7 with isolated PL bundle rupture. EUA analysis demonstrated that patients with isolated PL bundle rupture had increased pivot shift and Lachman test laxity, whereas the AM bundle rupture group had increased laxity with the anterior drawer test. Compared to previously published IKDC scores, there were no difference between isolated bundle augmentation and standard ACL reconstruction. However the KOOS scores showed significantly increased Sports function scores which was significantly better in the isolated bundle augmentations (93/100 v's 74/100). Differences between isolated AM and PL bundle reconstructions were not distinguishable.

Isolated ACL bundle tears make up a significant proportion ACL injuries. Although technically more difficult than standard ACL reconstruction, isolated bundle augmentation appears to result in improved sports function when compared to standard ACL reconstruction.

Purpose

The aim of this study was to compare the short-term and mid-term outcome of lateral UKRs using a single prosthesis, the AMC Uniglide knee implant.

Introduction

Kneeling ability is better in unicompartmental than total knee arthroplasty. There is also an impression that mobile bearing knees achieve better functional outcome than their fixed bearing cousins in unicompartmental and to a lesser extent total joint arthroplasty. In the UK, the market leading unicompartmental replacement is mobile bearing.

Background

Body Mass Index (BMI) is used to quantify generalised obesity, but does not account for variations in soft tissue distribution.

Purpose of the study

Assessing medium term outcome of medial Uni compartmental replacement and whether there is a difference in outcome between mobile and fixed bearing variants of the same prosthesis.

Cutaneous nerve injury occurs commonly with knee arthroplasty, causing altered skin sensation and, infrequently, the formation of painful neuromas. The infrapatellar branch of the saphenous nerve is the structure most commonly damaged.

The aim of this study was to establish the frequency of cutaneous nerve injury with three incisions commonly used in knee arthroplasty.

Ten knees from five cadavers were studied. Skin strips representing three different incisions, were excised and examined for number and thickness of nerves.

There were more nerve endings found in the dermis layer than the subcutaneous fatty layer. There was no significant difference in the total number of nerves when the 3 studied incisions were compared. The lower part of all incisions was found to have more thick and a higher number of nerves than the upper part (P=0.005).

Careful incision placement is required to avoid damage to cutaneous nerves during knee arthroplasty. This may be of long-term advantage to patients especially those for whom kneeling is important.

We present 10–15 year follow-up of 33 patients who underwent Elmslie-Trillat osteotomy for severe patellar subluxation or dislocation. In the literature it has been reported that tibial tubercle osteotomy predisposes to subsequent patella-femoral arthritis, however it has never been documented if pre existent knee chondral damage has any role in this development. In our group all patients had pre-op knee arthroscopy performed and extant of chondral damage was documented. We pre-formed an evaluation by long-term follow-up to determined weather pre-op chondral damage was the cause of subsequent osteoarthritis of patella-femoral joint.

All patients were invited to attend outpatient clinic for clinical examination and knee radiographs and assessed by an independent research surgeon. Mean age at follow-up was 43 years and average follow-up was 10.5 years (range 10–15 years). 90% follow-up was achieved. Knee function was assessed by clinical scores (Lysholm knee score, American Knee Score, Oxford Knee score, Tegner and Insall knee scores) and three radiographs (AP, Lateral and Merchant views) were performed.

Four patients had developed significant arthritis and underwent joint arthroplasty. Majority of patients reported good results with no further dislocation. However we noticed that extant of pre-op chondral damage was a significant factor in subsequent development of patella-femoral arthritis. We will present our data which is unique as no previous such long-term results have been reported for tibial tubercle transfers followed-up for more than 10 years and have pre-op arthroscopic documented chondral damage.

Introduction: There is an impression among Orthopaedic surgeons that mobile bearing knee replacement has a better functional outcome than fixed bearing knee replacement. Since kneeling demands a high level of function after knee replacement this study was undertaken to see if mobile bearings in either total or unicompartmental replacement conferred an advantage.

Methods: A prospective randomised study of 207 TKR patients receiving the same prosthesis (Rotaglid, Corin, UK) was performed. Patients were randomised into a mobile bearing group (102 patients with a mean age of 53 years) and a fixed bearing group (105 patients with a mean age of 55 years). Data was also prospectively collected on 215 UKR patients who received the same unicompartmental implant (AMC, Uniglide, Corin, UK). 136 patients (Mean age: 62 yrs) had a mobile insert and 79 (mean age: 65 yrs) a fixed insert.

All patients completed the Oxford Knee Questionnaire preoperatively as well as at 1 and 2 years postoperatively. Their stated kneeling ability and total scores were analysed with a perfect score for kneeling ability being 4, and 48 the maximum total score.

Results: In all groups both the kneeling ability and the total scores improved markedly from their preoperative state. At two years the total score for the fixed bearing devices was marginally better than for the mobile (Rotaglide 36;31 and Uniglide 37;33)

There was a more striking difference with respect to kneeling ability with the fixed bearing variants performing better, (Rotaglide 1.4; 0.9 and Uniglide 1.9; 1.4), However, the greatest difference was between the UKR and TKR groups (UKR 1.7; TKR 1.2). Pre-operatively less than 2% of TKR patients (7% of the UKR patients) could kneel. Post-operatively, the patients’ kneeling ability improved with 21% for the mobile bearing, 32% of fixed bearing UKR patients. The TKR patients kneeling ability was 13% of the mobile, 26% of fixed bearing patients were able to kneel with little or no difficulty. In all groups the stated kneeling ability was poor with less than 50% of any group being able to kneel with ease or only minor difficulty.

Conclusion: Those undergoing UKR appeared to perform better than those with a TKR. None of the forms of knee replacement used resulted in good kneeling ability, though this function was improved by arthroplasty in all groups. Mobile bearing inserts

Introduction: Force plate analysis of contact areas and pressure has been used in the fields of podiatry and foot surgery. We used this tool in assessing normal subjects and knee replacement patients kneeling.

Aim: We analysed contact areas and pressures over the front of the knee during different kneeling positions.

Methods: Twenty three normal subjects and 33 knee replacement patients were included in this study. The patients were selected according to age and kneeling ability and the absence of involvement of other joints. They had unilateral or bilateral Total (TKR) or Unicompartmental knee replacements (UKR).

Target points were identified on the plate and patients were asked to place their tibial tuberosity on the target sites.

Patients and normal subjects’ data of load, contact area and pressure were recorded with knee at 90 degrees. A second reading was taken with subjects kneeling in their maximum flexion comfortable position. Foot position during kneeling was recorded in each case.

Results: Average age was 48.3 years for the normal group and 65.5.2 for the replaced knee group. Average range of motion was 141 degrees for the normal group and 115 degrees for the replaced knees group.

In the normal group, there was a significant positive correlation between body mass and kneeling load at both 90 degrees and maximum flexion. Kneeling pressure was never identical in both knees in all groups. There was no significant difference of peak pressures and contact areas between the normal and UKR group.

The angle of flexion affected the contact pressures as going from 90 degrees to higher flexion with the body weight still actively supported increases contact pressure, which then dropped to lowest level in maximum flexion when the body weight was supported by the calf. Peak loads were usually in the region of the tibial tuberosity.

Conclusion: Kneeling may be a sided activity with each individual having a dominant knee. The UKR group showed more normal kinematics in comparison with the TKR group.

Maximum contact pressures decreased in knees able to achieve full flexion. As kneeling flexion angle increases, the contact area decreases and while the thigh is off the calf and the peak pressure increases. Contact pressure dropped to below 90 degrees level whenever full flexion was achieved.

Introduction: There is an impression among Orthopaedic surgeons that mobile bearing knee replacement has a better functional outcome than fixed bearing knee replacement. Since kneeling demands a high level of function after knee replacement this study was undertaken to see if mobile bearings in either total or unicompartmental replacement conferred an advantage.

Methods: A prospective randomised study of 207 TKR patients receiving the same prosthesis (Rotaglid , Corin, UK) was performed. Patients were randomised into a mobile bearing group (102 patients with a mean age of 53 years) and a fixed bearing group (105 patients with a mean age of 55 years).

Data was also prospectively collected on 215 UKR patients who received the same Unicompartmental implant (AMC, Uniglide, Corin, UK). One hundred and thirty six patients (Mean age: 62 yrs) had a mobile insert and 79 (mean age: 65 yrs) a fixed insert.

All patients completed the Oxford Knee Questionnaire preoperatively as well as at 1 and 2 years postoperatively. Their stated kneeling ability and total scores were analysed with a perfect score for kneeling ability being 4 and 48 the maximum total score.

Results: In all groups both the kneeling ability and the total scores improved markedly from their preoperative state. At two years the total score for the fixed bearing devices was marginally better than for the mobile (Rotaglide 36;31 and Uniglide 37;33)

There was a more striking difference with respect to kneeling ability with the fixed- bearing variants performing better, (Rotaglide 1.4; 0.9 and Uniglide 1.9; 1.4), However, the greatest difference was between the UKR and TKR groups (UKR 1.7; TKR 1.2). Pre-operatively less than 2% of TKR patients (7% of the UKR patients) could kneel. Post-operatively, the patients’ kneeling ability improved with 21% for the mobile bearing, 32% of fixed bearing UKR patients.

The TKR patients kneeling ability was 13% of the mobile, 26% of fixed bearing patients were able to kneel with little or no difficulty. In all groups the stated kneeling ability was poor with less than 50% of any group being able to kneel with ease or only minor difficulty.

Conclusion: Those undergoing UKR appeared to perform better than those with a TKR. None of the forms of knee replacement used resulted in good kneeling ability, though this function was improved by arthroplasty in all groups. Mobile bearing inserts did not confer any advantage with respect to kneeling and in fact performed worse with regard to this particular knee function.

Purpose: To review long-term outcome following knee arthrodesis, and compare this with patient outcome following revision knee arthroplasty.

Methods: Case notes and radiographs of patients who underwent arthrodesis using the Mayday nail were reviewed retrospectively for evidence of clinical and radiological union. Patients also completed an SF12 health survey and Oxford knee score in the form of postal questionnaires. Each patient was matched with patients who had undergone revision knee arthoplasty and the outcomes were compared.

Results: 19 patients were reviewed who underwent knee arthrodesis using a Mayday nail in two centres between 1993 and 2004. 18 cases had united clinically and radiologically with one case lost to follow-up. Mean SF12 scores of patients following knee arthrodesis indicated severe physical (28.8) but only mild mental (43.3) disabilities. The mean Oxford knee score in this group was 41.0. These results were comparable with matched patients following revision knee arthroplasty who scores 27.2 (physical) and 41.1 (mental) on the SF12, and a mean of 38.8 on the Oxford knee score.

Conclusion: Outcome scores following knee arthrodesis were similar to those following revision knee arthroplasty making it an option worth considering in selected patients requiring revision surgery.

Discussion: The Mayday nail provides a method of knee arthrodesis with a high union rate and an acceptable complication rate. Outcome scores following arthrod-esis were not dissimilar to those following revision total knee replacement. These results suggest that knee arthrodesis may be considered as an acceptable alternative to complex knee revision surgery.

The aim of this study was to measure intra-articular gentamicin levels at the 2^nd stage revision following the use of an antibiotic impregnated articulating spacer.

Infected total knee replacements are a cause of considerable morbidity often requiring revision in two stages. Rings of bone cement, cement moulds and spacer devices are available for use following the initial debridement and removal of infected metalwork. The availability of antibiotic impregnated articulating spacers are potentially attractive to achieve a high local dose of antibiotic and to maintain a good range of movement.

Seven patients underwent a two stage revision of their total knee replacements. Following the initial debridement an antibiotic impregnated articulating spacer was cemented in place. At the 2^nd stage revision a perioperative joint aspirate and blood sample was taken and gentamicin levels measured. The range of movement was assessed.

The average gentamicin levels were 0.72mg/l (0.24 – 2.36mg/l). A good range of movement was maintained in all cases. At these levels the gentamicin would be therapeutic.

Antibiotic impregnated articulating spacers possess several potential advantages to the revision knee surgeon by helping maintain the range of movement and provide local release of antibiotics. Their use should be considered in such cases.

Purpose: This study was carried out to compare the alteration in skin sensation following midline, medial and short medial incisions for knee replacement.

Method: 88 patients with 102 replaced knees were examined for altered skin sensation over the front of the knee, all were at least 18 months from their knee replacement. Twenty-one knees had a medial incision, 38 a midline incision and 43 a short medial incision for UKR.

A scale of −2 to +2 was used to measure different degrees of skin hypo or hyperaesthia. A purpose-designed grid, designed to fit different knee sizes, was used to record sensations. A computer programme was created to record all patients’ data including the length and shape of the incision in relation to anatomical landmarks.

A parallel histological study was carried out on 18 skin specimens taken from the 2 standard incisions. The specimens were prepared and stained for nerve endings. The number of nerve endings in each incision was calculated.

Results Histologically, less cutaneous nerve endings were seen in specimens from midline incisions than medial incisions.

Discussion: Altered skin sensation is unpleasant to many patients at least initially and may affect function especially kneeling. The midline line incision seems to produce less dermal parasthesia than the medial incision, this probably relates to both the wound position and the density of nerve endings. As expected, the length of incision correlated with the area of numbness when comparing short and long medial incisions.

Introduction and Aims: Kneeling is an important function of the knee joint but little information is available on ability to kneel after different types of knee arthroplasty. We aimed to assess patients’ kneeling ability pre- and post-operatively after uni-compartmental, patellofemoral and total knee arthroplasty (UKR, PFR, TKR) and to objectively examine: kneeling ability, factors that affect it and whether this ability differed from the patient’s perception.

Method: In 253 knee arthroplasty cases, we prospectively analysed the ability to kneel pre-operatively, and post-operatively at one and two years using the relevant section of the Oxford Knee Score questionnaire. One hundred and twenty-two post-operative patients (38 TKR, 53 UKR, 31 PFR) were then examined to assess their actual kneeling ability.

Results: Patients’ perception of their kneeling ability prior to surgery was poor in all three groups (mean score 0.7 out of 4) and improved in all groups after surgery (mean score at two years 1.46 out of 4). Perceived kneeling ability was best in UKR and worst in PFR (P< 0.001). Perceived kneeling ability improved most in the first year post-operatively, but continued to improve between one and two years although the final kneeling function was still not good. When examined, only 37% of patients thought they could kneel, whereas 81% were actually able to kneel (P< 0.001). Ability to kneel was significantly better than perceived ability for all prosthesis types (P< 0.001). Kneeling ability was better in men and associated with an increased range of movement (P< 0.001).

Conclusion: Kneeling ability is poor prior to knee arthroplasty and improves up to two years post-operatively, though it is still perceived to be poor, but can be improved with rehabilitation. UKR gave better kneeling ability than PFR or TKR. Patient-centred questionnaires do not accurately document kneeling ability after knee arthroplasty.

Introduction and Aims: Cold therapy is known to reduce pain and swelling after surgical procedures on the knee. We hypothesised that if cold therapy is started earlier, then there would be a reduction in pain and swelling in patients undergoing arthroscopic anterior cruciate ligament [ACL] reconstruction.

Method: We prospectively randomised 40 patients undergoing arthroscopic ACL reconstruction with hamstring autograft, to receive either room temperature [19° C] or cold [4° C] arthroscopy irrigation fluid. Patients were then assessed over the following seven days, with regard to pain [measured on a visual analogue scale], and swelling [measured with limb girth at four points around the knee].

Results: Pain scores were consistently reduced in the cold fluid group compared to the room temperature group throughout the post-operative period, and this difference was significant [p< =0.05] from six hours until seven days post-operatively. At day seven, the swelling measured at 5cm below the joint and 5cm above the joint were significantly lower in the cold group compared with the room temperature group. Drainage from the intra-articular drain was significantly lower in the cold group.

Conclusion: The use of cold irrigation fluid is a simple and safe measure by which pain and swelling (at day 7) can be reduced in the early post-operative period for arthroscopic ACL reconstruction.

Aim: The aim of this study was to evaluate the functional results and ease of performing revision surgery after a primary unicompartmental arthroplasty versus primary total knee arthroplasty.

Method: 114 revision TKRs had data collected prospectively as part of our unit’s Knee Database. 45 were revisions of UKR’s and 79 revisions of TKR’s. This data included Bristol Knee Scores (BKS), reason for revision, use of implant augments and bone graft. Measurements were also made of the ability to restore joint-line after revision.

Results: In both groups there was a significant improvement in BKS post-operatively. In the UKR group the commonest reason for revision was progression of disease, while in the TKR group it was aseptic loosening. Bone graft was required in significantly fewer UKR cases (20% vs 40%, P< 0.05). Distal femoral augments were used in 45% of the TKR revisions but in none of the revisions from UKR. The joint line was elevated in a significantly higher proportion of revision from TKR cases versus revision from UKR cases (P< 0.001). Revisions from UKR had higher Total BKS and Functional BKS score than revisions from TKR.

Conclusions: Revision TKR after a primary UKR requires less bone graft, fewer augments, restores the joint line more frequently and gives improved functional results over revisions after primary TKR.

Introduction The aim of this study was to examine the flexion stability of posterior stabilised (PS) compared with deep dished (DD) tibial inserts in PCL sacrificing total knee arthroplasty using posterior stress radiography.

Methods Kneeling posterior stress radiographs at 90° of flexion were taken pre and post-operatively in 36 knees undergoing primary arthroplasty with PCL resection (26 DD and 10 PS implants). Sagittal plane tibial translation was measured.

Results The deep dish inserts all showed posterior displacement (mean: −5.1 mm, range: −2 to −12 mm). The posterior stabilised implants were all displaced anteriorly (mean: +6.7 mm, range: +3 to +12 mm). The difference in translation was highly significant (P< 0.0001). There was a strong correlation between implant and position of the tibia (R = 0.86). In seven patients comparison was possible between a DD component in one knee and a PS implant in the other. There was a mean post-operative side to side difference of 11 mm (range: 5 to 21 mm).

Conclusions This study discriminates between two implant types on stress x-rays. The posterior tibial displacement in the DD group suggests that this implant does not provide enough posterior flexion stability to compensate for the PCL resection. The anterior translation in the PS group has implications for the design and wear of the post as well as advice to patients about possibly avoiding kneeling in this PS design.

Aim: To assess the functional results of revision TKR with the PFC/TC3 system, and to correlate this with the reasons for revision and restoration of joint height. Method: 153 patients underwent revision TKR using the PFC/TC3 system. Data was prospectively collected (using the Bristol Knee Score) pre-operatively and at a mean of 4.2 years post-revision. 43 revisions were for infection and 81 revisions were for aseptic loosening. Measurements of the joint height were made pre and post-operatively using FiggieÔs method and were divided into 3 groups: lower by more than 5mm, restored and elevated more than 5mm. Use of distal augments and polyethylene thickness were recorded. Results: The mean pre-op function score was 12 and post-operatively was 19 for the infection group and 20 for the aseptic loosening group. Revision after initial UKR gave a mean score of 21, while revision after TKR gave a mean score of 18 (max 27). Knees in which the joint line was elevated by more than 5 mm had a mean score of 17 while those where the joint line was restored had a mean score of 19. Recent increasing use of distal augments improved the joint line and results. Conclusion: revision using the PFC/TC3 system produced acceptable medium term functional results and good survival. Better restoration of joint line and functional results were achieved by distal femoral rather than proximal tibial augmentation.

Aim: To examine the flexion stability of posterior stabilised (PS) vs deep dished (DD) tibial inserts, in PCL sacrificing total knee arthroplasty using posterior stress radiography. Methods: A simple jig was designed to allow kneeling posterior stress radiographs (at 90 degrees flexion) to be taken. This method was used to take pre and post-operative radiographs in 36 knees undergoing primary arthroplasty with PCL resection (26 DD and 10 PS implants). Sagittal plane tibial translation was measured. Results: The DD inserts all showed posterior displacement (mean: −5.1 mm, range: −2 to −12mm). The PS implants were all displaced anteriorly (mean: +6.7mm, range: +3 to +12mm). The difference in translation was highly significant (P< 0.0001). There was a strong correlation between implant and position of the tibia (R=0.86). In 7 patients, comparison was possible between a DD component in one knee and a PS implant in the other. There was a mean post-operative side-to-side difference of 11mm (range: 5 to 21mm). Conclusions: This study validates a simple new method for flexion stress x-rays (by accurately discriminating between the two implant types). The posterior tibial displacement in the DD group suggests that this implant does not provide enough posterior flexion stability to compensate for the PCL resection. The anterior translation in the PS group has implications for the design and wear of the post, as well as advice to patients about possibly avoiding kneeling in this PS design.