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.

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

Bone stock loss is a major challenge to the revision hip surgeon. Impaction grafting is frequently the preferred option for the surgeon when faced with bone stock deficiency. This retrospective study assesses a consecutive series of patients who underwent revision hip replacement with femoral impaction grafting during the period 1994–2001. Radiographic measurement for stem subsidence was carried out by 2 independent observers on pre-operative and post-operative radiographs at 6 months, 1 year, 18 months and 2 years following surgery. Graft incorporation and trabecular remodelling were also subjectively assessed. Irradiated bone allograft was used in all cases.

Sixty-nine hips were reviewed. Radiographic analysis revealed graft incorporation in 38% of cases. However, there was no evidence of trabecular remodelling. Moderate subsidence (5–10 mm) occurred in 10 cases (14.5%), and massive subsidence (> 10 mm) occurred in 5 cases (7.2%). The survivorship with re-revision or need for further surgery as the end point was 92.8% at an average of 28 months.

The results obtained in this study are less favourable than other reported studies of revision of the femoral stem using impaction bone grafting. The absence of the characteristic changes of graft remodelling reported in other series raises concerns that irradiated bone graft may be a significant factor in the post-operative progress.

Loss of bone stock is a major problem in revision surgery of the hip. Impaction bone grafting of the femur is frequently used when dealing with deficient bone stock. In this retrospective study a consecutive series of 68 patients (69 hips) who had revision of a hip replacement with femoral impaction grafting were reviewed. Irradiated bone allograft was used in all hips. Radiological measurement of subsidence of the stem, incorporation of the graft and remodelling was carried out and showed incorporation of the graft in 26 of 69 hips (38%). However, there was no evidence of trabecular remodelling. Moderate subsidence of 5 mm to 10 mm occurred in ten hips (14.5%), and massive subsidence of > 10 mm in five (7.2%).

The results of this study are less favourable than those of others describing studies of revision of the femoral stem using impaction bone grafting. The absence of the characteristic changes of graft remodelling noted in other series raises the question as to whether irradiated bone graft may be a significant factor influencing the post-operative outcome.

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: 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.

Aim: The Low Contact Stress (LCS) Total Knee Replacements (TKR) is a well-established mobile bearing prosthesis with more than 25 year experience, while the Kinemax Plus is a well established fixed bearing prosthesis. We examined whether reproducing the joint line height to within 5 mm of the pre-operative joint line height had any impact on the clinical outcome in the two different types of Total Knee Replacements.

Method: 48 consecutive LCS knee replacements with a minimum of 2 years follow up had their pre and postoperative joint line (using Figgie’s method) and range of movement (ROM) measured. We used the Oxford Knee Score as a clinical outcome measurement tool.

A cohort group of 53 CR Kinemax plus TKR from the Bristol Knee group was matched for age and sex. They had the same parameters measured.

Results: Accurate joint line restoration was achieved significantly more frequently (P< 0.05) in the Kinemax group. Better post-operative ROM also occurred in the Kinemax group than the LCS, p = 0.03 and the former produced a bigger gain in ROM p < 0.01. However, no difference in the Oxford Knee Score existed between the two prostheses, p = 0.28.

Joint line: elevation K+ LCS

0–2 mm (16/48) = 33% (26/53) = 49% 2–5 mm (14/48) = 29% (14/53) = 26%> 5 mm (18/48) = 38% (12/53) = 25%

There was no significant difference in the ROM or Oxford Knee Score when the joint line was not elevated versus elevated for each prosthesis. However, there was suggestion that the ROM in LCS might be more sensitive to joint line changes, although this was not significant.

ROM

K+ LCS

Normal joint line 116° 105°

Elevated joint line 108° 101°

Conclusion: Accurate joint line restoration could not be shown to correlate with either improved ROM or Oxford knee score; probably because of the small mount of elevation encountered and the small study size. There was a significantly greater post-operative increase in ROM with the Kinemax Plus relative to the LCS, and a significantly closer restoration of the joint line with the Kinemax Plus, both with respect to the actual measurement and with respect to the proportion of cases in which the joint line was accurately reproduced. This is surprising since in most K+ cases additional distal femur had been resected to avoid a tight knee. While in the LCS group special efforts had been made to achieve accurate restoration of the joint level.

Introduction: Impaction bone grafting is a very useful technique in the armament of a revision hip surgeon. Traditionally fresh frozen allograft has been used for this technique. However there are concerns about the transmission of viral proteins and prions through this form of allograft.As a result irradiated bone graft has been favoured in some centres. There is no long term series describing the results of impaction bone grafting using irradiated bone

Method: We describe a series of 58 cases of acetabular revision surgery done at the Avon Orthopaedic Centre between 1995 and 2001 and followed up over a period of 48–90 months. The preoperative bone defect was graded by the Paprosky classification. There were 10cases of type 1,15 type 2a, 5 type 2b, 7 type 2c, 14 type 3a and 7 type 3c.50 cases were operated by the two senior surgeons and 8 were senior trainees.All uncontained defects were first contained by using a mesh or cages. The bone graft used was freeze-dried femoral head allograft, which was milled and used without defatting. The cases were followed up clinically and radiologically.Case notes were reviewed to gain information about the primary prosthesis, and operative details as well as the cause of the revision. All the cases were the first revisions.

The radiological picture was evaluated for signs of incorporation, remodelling, loosening and migration of the cemented acetabular component. Clinical evaluation was from the last clinic visit and included the presence of pain, mobility status, range of movement and patient satisfaction. Revision was the end point of the study

Results: There were no cases which underwent loosening and all the cups were stable.1 case had recurrent dislocation and was revised.26 (44.8%) cases showed changes of incorporation, and 4 cases (6%)showed changes of remodelling.23 cases (39.6%) underwent femoral impaction grafting as well. Clinically the results were satisfactory with absence of pain in 38 cases (65%). Trochanteric pain was present in 3 cases.

Conclusion: The results suggested that the results of impaction bone grafting on the acetabular side using irradiated bone graft are comparable to those with fresh frozen allograft and significantly better than those on the femoral side. This could be attributed to the compressive forces acting across the acetabular side as against the predominantly shear forces acting on the femur. The low percentage of remodelling remains a concern and warrants further studies.

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.

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 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 12 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 The average length for the medial incision was 17 cm with an average post-operative time of 3.37 yrs and skin numbness of 87.78 cm square.

The midline incision average length was 17.85 cm with an average post-operative time of 4.7 yrs and a numb area of 73.7 cm square.

The short medial incision used for UKR averaged to be 9 cm in length with an average post operative time of 3.9 yrs and an area of numbness of 48.1 cm square.

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

Discussion 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. The length of the incision correlated with the area of numbness when comparing the short and long medial incisions.

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.

The aim of this study was to analyse the kneeling ability of patients before and at one and two years after total (TKR), unicompartmental (UKR) and selective patellofemoral (PFR) knee arthroplasty, for osteoarthritis. Method: Data was prospectively collected on 253 knees, which underwent either TKR, UKR or PFR. A kneeling score was obtained by analysis of the relevant section of the Oxford Knee Score questionnaire. Scores were obtained pre-operatively and at 1 and 2 years post-operatively (minimum score 0, maximum 4). Absolute values and change following arthroplasty were recorded. Correlations with pain and other knee functions were also made.

Results: Kneeling ability prior to surgery was poor in all three groups (mean score 0.7 out of 4) and improved significantly after surgery (mean score at one year 1.13 and at two years 1.46 out of 4) (P< 0.001). Kneeling ability at 1 year differed significantly with operation type (p = 0.02). Kneeling ability improved most in the first year post-operatively but continued to improve between one and two years although the final function was still not good. Kneeling ability was best in UKR and worst in PFR, with the difference between these prostheses being statistically significant (P< 0.001).

Conclusion: Kneeling ability in osteoarthritic knees is poor but improves with arthroplasty. However, the majority of patients will still have difficulty kneeling.

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: One hundred and fifty three 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. Forty three revisions were for infection and 81 revisions were for aseptic loosening. Measurements of the joint height were made pre and post-operatively using Figgie’s method and were divided into three 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 1 9. 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.