Objectives

Up to 40% of unicompartmental knee arthroplasty (UKA) revisions are performed for unexplained pain which may be caused by elevated proximal tibial bone strain. This study investigates the effect of tibial component metal backing and polyethylene thickness on bone strain in a cemented fixed-bearing medial UKA using a finite element model (FEM) validated experimentally by digital image correlation (DIC) and acoustic emission (AE).

As many as 25% to 40% of unicompartmental knee replacement (UKR) revisions are performed for pain, a possible cause of which is proximal tibial strain. The aim of this study was to examine the effect of UKR implant design and material on cortical and cancellous proximal tibial strain in a synthetic bone model. Composite Sawbone tibiae were implanted with cemented UKR components of different designs, either all-polyethylene or metal-backed. The tibiae were subsequently loaded in 500 N increments to 2500 N, unloading between increments. Cortical surface strain was measured using a digital image correlation technique. Cancellous damage was measured using acoustic emission, an engineering technique that detects sonic waves (‘hits’) produced when damage occurs in material.

Anteromedial cortical surface strain showed significant differences between implants at 1500 N and 2500 N in the proximal 10 mm only (p < 0.001), with relative strain shielding in metal-backed implants. Acoustic emission showed significant differences in cancellous bone damage between implants at all loads (p = 0.001). All-polyethylene implants displayed 16.6 times the total number of cumulative acoustic emission hits as controls. All-polyethylene implants also displayed more hits than controls at all loads (p < 0.001), more than metal-backed implants at loads ≥ 1500 N (p < 0.001), and greater acoustic emission activity on unloading than controls (p = 0.01), reflecting a lack of implant stiffness. All-polyethylene implants were associated with a significant increase in damage at the microscopic level compared with metal-backed implants, even at low loads. All-polyethylene implants should be used with caution in patients who are likely to impose large loads across their knee joint.

Cite this article: Bone Joint J 2013;95-B:1339–47.

The lateral compartment is predominantly affected in approximately 10% of patients with osteoarthritis of the knee. The anatomy, kinematics and loading during movement differ considerably between medial and lateral compartments of the knee. This in the main explains the relative protection of the lateral compartment compared with the medial compartment in the development of osteoarthritis. The aetiology of lateral compartment osteoarthritis can be idiopathic, usually affecting the femur, or secondary to trauma commonly affecting the tibia. Surgical management of lateral compartment osteoarthritis can include osteotomy, unicompartmental knee replacement and total knee replacement. This review discusses the biomechanics, pathogenesis and development of lateral compartment osteoarthritis and its management.

Cite this article: Bone Joint J 2013;95-B:436–44.

This prospective randomised controlled double-blind trial compared two types of PFC Sigma total knee replacement (TKR), differing in three design features aimed at improving flexion. The outcome of a standard fixed-bearing posterior cruciate ligament-preserving design (FB-S) was compared with that of a high-flexion rotating-platform posterior-stabilised design (RP-F) at one year after TKR.

The study group of 77 patients with osteoarthritis of the knee comprised 37 men and 40 women, with a mean age of 69 years (44.9 to 84.9). The patients were randomly allocated either to the FB-S or the RP-F group and assessed pre-operatively and at one year post-operatively. The mean post-operative non-weight-bearing flexion was 107° (95% confidence interval (CI) 104° to 110°)) for the FB-S group and 113° (95% CI 109° to 117°) for the RP-F group, and this difference was statistically significant (p = 0.032). However, weight-bearing range of movement during both level walking and ascending a slope as measured during flexible electrogoniometry was a mean of 4° lower in the RP-F group than in the FB-S group, with 58° (95% CI 56° to 60°) versus 54° (95% CI 51° to 57°) for level walking (p = 0.019) and 56° (95% CI 54° to 58°) versus 52° (95% CI 48° to 56°) for ascending a slope (p = 0.044). Further, the mean post-operative pain score of the Western Ontario and McMaster Universities Osteoarthritis Index was significantly higher in the RP-F group (2.5 (95% CI 1.5 to 3.5) versus 4.2 (95% CI 2.9 to 5.5), p = 0.043).

Although the RP-F group achieved higher non-weight-bearing knee flexion, patients in this group did not use this during activities of daily living and reported more pain one year after surgery.

Objectives

To evaluate the neck strength of school-aged rugby players, and to define the relationship with proxy physical measures with a view to predicting neck strength.

We have reviewed the literature to establish the role of lateral retinacular release in the management of disorders of the extensor apparatus of the knee. The scientific evidence for intervention is explored and reports on outcome are discussed.

Modifications in the design of knee replacements have been proposed in order to maximise flexion. We performed a prospective double-blind randomised controlled trial to compare the functional outcome, including maximum knee flexion, in patients receiving either a standard or a high flexion version of the NexGen legacy posterior stabilised total knee replacement. A total of 56 patients, half of whom received each design, were assessed pre-operatively and at one year after operation using knee scores and analysis of range of movement using electrogoniometry. For both implant designs there was a significant improvement in the function component of the knee scores (p < 0.001) and the maximum range of flexion when walking on the level, ascending and descending a slope or stairs (all p < 0.001), squatting (p = 0.020) and stepping into a bath (p = 0.024). There was no significant difference in outcome, including the maximum knee flexion, between patients receiving the standard and high flexion designs of this implant.

Injury to the common peroneal nerve was present in 14 of 55 patients (25%) with dislocation of the knee. All underwent ligament reconstruction. The most common presenting direction of the dislocation was anterior or anteromedial with associated disruption of both cruciate ligaments and the posterolateral structures of the knee. Palsy of the common peroneal nerve was present in 14 of 34 (41%) of these patients. Complete rupture of the nerve was seen in four patients and a lesion in continuity in ten.

Three patients with lesions in continuity, but with less than 7 cm of the nerve involved, had complete recovery within six to 18 months. In the remaining seven with more extensive lesions, two regained no motor function, and one had only MRC grade-2 function. Four patients regained some weak dorsiflexion or eversion (MRC grade 3 or 4). Some sensory recovery occurred in all seven of these patients, but was incomplete. In summary, complete recovery occurred in three (21%) and partial recovery of useful motor function in four (29%). In the other seven (50%) no useful motor or sensory function returned.

Introduction: Traumatic knee dislocations are rare but devastating injuries. We have evaluated the clinical results of ligament repair and reconstruction. Knee dislocation was defined as an acute event that produced multidirectional instability with at least 2 of the 4 major ligaments disrupted.

Materials: Twenty-one patients with 22 knee dislocations presented between 1994 and 2001. There was one vascular and one common peroneal nerve injury. Eight (38%) patients were treated in the acute period (< 14 days), 5 (24%) had reconstructions within 1 year of injury. The remainder were late reconstructions. The patients were evaluated at mean follow-up of 32 months (11 to 77). This included ROM measurement, clinical and instrumented ligament laxity testing. Posterior stress view with 10kg weight was used to evaluate the PCL reconstruction. Function was evaluated using the IKDC chart, the Lysholm Score, the Tegner Activity Level, the Knee Outcome Survey and WOMAC.

Results: The mean extension deficit was 6.8 degrees (0–25) and mean flexion deficit was 8.6 degrees (0–20). Of the ACL reconstructions, 4 knees had 0–3mm side-to-side difference, 15 knees had 3–5mm and 1 knee had 6–10mm. Of the PCL reconstructions, 2 were within 3–5mm of side-to-side difference, 9 knees were 6–10mm and 4 were more than 10mm. Posterolateral corner repair/reconstructions appeared durable. None of the knees were IKDC Grade A, 8 knees were Grade B, 9 were as Grade C and 5 were Grade D. The mean Lysholm Score was 81 (66–100) and the mean Tegner Activity Level was 4.9 (1–7). The mean Knee Outcome Survey score was 75 (41–99). Acutely treated knees had better scores than late reconstructions.

Conclusion: Our study has demonstrated good function in the operatively treated knee dislocations at 1–7 years. Nearly all had few problems with daily activities. The ability to return to high-demand sports and heavy manual labour was less predictable.

We treated 21 patients with 22 dislocations of the knee by repair or reconstruction of all injured ligaments. Eight knees were treated in the acute phase (less than two weeks after injury); the remainder were treated more than six months after injury (6 to 72). Reconstructions were carried out with a combination of autograft and allograft tendons and by direct ligament repair where possible. At a mean follow-up of 32 months (11 to 77) the mean Lysholm score was 87 (81 to 91) in the acute group and 75 (53 to 100) in the delayed group. The mean Tegner activity rating was 5 in the acute group and 4.4 in the delayed group.

The International Knee Documentation Committee assessment revealed no differences between the two groups. Instrumented testing of knee stability indicated better results for anterior cruciate ligament reconstructions which had been undertaken in the acute phase, but no difference in the outcome of posterior cruciate ligament reconstructions. There was no difference in the loss of knee movement between the two groups. Although the differences were small, the outcome in terms of overall knee function, activity levels and anterior tibial translation were better in those knees which had been reconstructed within two weeks of injury.

Traumatic knee dislocations are rare but devastating injuries. We have evaluated the clinical results of ligament repair and reconstruction. Knee dislocation was defined as an acute event that produced multidirectional instability with at least 2 of the 4 major ligaments disrupted.

Twenty-one patients with 22 knee dislocations presented between 1994 and 2001. There was one vascular and one common peroneal nerve injury. Eight (38%) patients were treated in the acute period (< 14 days), 5 (24%) had reconstructions within 1 year of injury. The remainder were late reconstructions. The patients were evaluated at mean follow-up of 32 months (11 to 77). This included ROM measurement, clinical and instrumented ligament laxity testing. Posterior stress view with 10kg weight was used to evaluate the PCL reconstruction. Function was evaluated using the IKDC chart, the Lysholm Score, the Tegner Activity Level, the Knee Outcome Survey and WOMAC.

The mean extension deficit was 6.8 degrees (0–25) and mean flexion deficit was 8.6 degrees (0–20). Of the ACL reconstructions, 4 knees had 0–3mm side-to-side difference, 15 knees had 3–5mm and 1 knee had 6–10mm. Of the PCL reconstructions, 2 were within 3–5mm of side-to-side difference, 9 knees were 6-10mm and 4 were more than 10mm. Posterolateral corner repair/reconstructions appeared durable. None of the knees were IKDC Grade A, 8 knees were Grade B, 9 were as Grade C and 5 were Grade D. The mean Lysholm Score was 81 (66–100) and the mean Tegner Activity Level was 4.9 (1–7). The mean Knee Outcome Survey score was 75 (41–99). Acutely treated knees had better scores than late reconstructions.

Our study has demonstrated good function in the operatively treated knee dislocations at 1–7 years. Nearly all had few problems with daily activities. The ability to return to high-demand sports and heavy manual labour was less predictable.

We conducted a prospective, randomised and double blinded study to observe the recovery of knee function in 50 patients undergoing knee replacement with or without patella resurfacing.

Patients were assessed pre-operatively, at four months and a minimum 18 months after surgery using three scoring systems, the Knee Society Clinical Outcome Score, WOMAC and the SF-36 health questionnaire. In addition the active range of knee movement when weight bearing was measured using an electrogoniometer. Patients were asked to undertake 11 standardised activities including level walking, stair climbing and getting into and out of low chairs. Patients were randomised at the time of surgery into receiving a knee replacement with or without patella resurfacing.

Forty-two patients, (18 with patella resurfacing, 24 with no resurfacing) completed assessments at all time intervals. All patients in the study demonstrated an improvement in terms of pain relief and function by four months after knee replacement with a further but less significant improvement by 18 months. The active range of knee movement measured by electrogoniometry recovered to the pre-operative range for all activities but there was no increase in knee movement. Patients who had patella resurfacing had a significantly lower (p < 0.02) score on the Knee Society Clinical Outcome function score at 18 months compared to patients without patella resurfacing. There was no significant difference (p > 0.05) in the active range of knee movement with or without patella resurfacing, although patients with patella resurfacing in general had slightly poorer range of movement particularly for activities that required knee flexion beyond 70 degrees.

We concluded that in this study knee function was not improved by patella resurfacing when compared to a matched group of patients without resurfacing. As patients recovery stabilises by 18 months it appears that the final functional outcome following knee replacement is not enhanced by patella resurfacing.

We report a prospective study of 49 patients who had arthroscopic subacromial decompression for chronic rotator-cuff impingement. All patients were assessed preoperatively and at 3, 6 and 12 months using the modified UCLA shoulder score.

The dominant arm was affected in 35 patients, but only 13 recognised overuse as a cause of their shoulder pain. Before operation, the UCLA shoulder score was poor or fair in all patients. After three months only 28% of patients had satisfactory relief of symptoms but at one year 85% of patients examined had a good or excellent result. Patients with calcific tendonitis recovered more quickly: 93% reported a good result at six months.

We conclude that arthroscopic subacromial decompression is an effective form of treatment, but that patients should be warned that recovery from surgery may be prolonged.