Osteotomy around the knee: evolution, principles and results.

PURPOSE: This article summarises the history and evolution of osteotomy around the knee, examining the changes in principles, operative technique and results over three distinct periods: Historical (pre 1940), Modern Early Years (1940-2000) and Modern Later Years (2000-Present). We aim to place the technique in historical context and to demonstrate its evolution into a validated procedure with beneficial outcomes whose use can be justified for specific indications. MATERIALS AND METHODS: A thorough literature review was performed to identify the important steps in the development of osteotomy around the knee. RESULTS: The indications and surgical technique for knee osteotomy have never been standardised, and historically, the results were unpredictable and at times poor. These factors, combined with the success of knee arthroplasty from the 1980s onward, led to knee osteotomy being regarded as an irrelevant surgical option by many surgeons. Despite its fluctuating reputation, this article demonstrates the reasons for the enduring practice of osteotomy, not least because achieving the appropriate alignment is now recognised as the foundation step when planning any surgical intervention. CONCLUSIONS: With appropriate patient selection, accurate pre-operative planning, modern surgical fixation techniques and rapid rehabilitation, osteotomy around the knee is now an effective biological treatment for degenerative disease, deformity, knee instability and also as an adjunct to other complex joint surface and meniscal cartilage surgery. LEVEL OF EVIDENCE: V.

A low-riding patella in posterior stabilised total knee replacements alters quadriceps' mechanical advantage, resulting in reduced knee flexion moments.

Abnormal in vivo Total Knee Replacement (TKR) kinetics is influenced by a range of factors, particularly by changes to the knee's geometric parameters such as the patellar tendon moment arm (PTMA). In this study, ground reaction force (GRF) measurements were combined with simultaneous fluoroscopic image measurements to investigate the relationship between abnormal TKR kinetics and geometric parameters. Nine Scorpio Cruciate Retaining (CR) TKR (Stryker, Newbury, UK), nine Scorpio Posterior Stabilized (PS) TKR and seven normal subjects performed a step-up activity on a forceplate in view of a fluoroscope. The TKR subjects were part of a larger ongoing randomised controlled trial. The maximum external knee flexion moment was 22.0% lower in the Scorpio PS group compared to the Scorpio CR group. No significant differences in PTMA were found between the groups. The Scorpio PS had a low-riding patella, with a 30.7% reduction in patellar height compared to the Scorpio CR. This was probably due to using a thick tibial insert after PCL release in the PS, and led to an 8° increase in patellar flexion angle which altered the patellar mechanism and reduced quadriceps' mechanical advantage. Consequently, PS subjects stepped-up more cautiously with a reduced knee flexion moment.

Bicruciate substituting total knee replacement: how effective are the added kinematic constraints in vivo?

PURPOSE: The Journey bicruciate substituting (BCS) TKR was designed to restore normal knee kinematics. It has two cam-post mechanisms which substitute for the ACL and PCL. The aim of this study was to undertake a comprehensive study of the Journey BCS kinematics in vivo to assess the function of the cam-post mechanisms and their effect on functional kinematics and compared to the kinematics of a group of normal knees. METHODS: The kinematics of 10 Journey BCS were assessed fluoroscopically during step-up and lunge exercises, and were compared to those of 20 normal knees. The fluoroscopic images were used to determine relative implant orientation using a 2D to 3D reconstruction method. The determined relative tibio-femoral orientations allowed for cam-post engagement and tibio-femoral contact points to be determined. Functional kinematics were assessed using the patella tendon angle (PTA) and the patella flexion angle (PFA) relationship with the knee flexion angle (KFA). RESULTS: The average maximum flexion achieved by the Journey was 124.7°. Both cam mechanisms engaged: The anterior cam during extension at 12.6° and the posterior cam in flexion at 45.4°. During flexion, the contacts points on the tibia moved posteriorly with no paradoxical anterior translation. The PTA/KFA relationships of the Journey implant group for both the step-up and lunge exercises were broadly similar in terms of trend to those established for the normal knee but the PTA between 10° KFA and 140° KFA were significantly (P < 0.05) lower than that for the normal knees. The PFA/KFA trend for both the implant and normal groups showed a linear relationship; however, the values of PFA were higher for the Journey compared to the normal. CONCLUSION: The Journey BCS showed no paradoxical anterior movement and sufficient posterior femoral roll back which corresponded with the engagement of the anterior and posterior cam-post mechanisms. Trends shown by the PTA/KFA and PFA/KFA kinematic profiles observed for the Journey group were more normal than those seen with other designs of TKR. However, despite being more close to normal than other implants, the Journey group showed a different kinematic profile to that of the normal knees, which is most likely due to the femur being too far posterior relative to the tibia. LEVEL OF EVIDENCE: Case-control study, retrospective, comparative study, Level III.

Improved quadriceps' mechanical advantage in single radius TKRs is not due to an increased patellar tendon moment arm.

Single femoral radius TKRs have been reported to improve quadriceps' mechanical advantage, leading to enhanced patient function. An increased patellar tendon moment arm (PTMA) has been cited as the main feature leading to improved quadriceps' mechanical advantage. However, these designs often incorporate a recessed trochlea which alters the patellar mechanism and may contribute to improved quadriceps' mechanical advantage. This study simultaneously measured the PTMA using two and three dimensional methods, as well as quadriceps forces (QF), patellofemoral kinematics and tibiofemoral kinematics in a motion analysis laboratory during an open chain leg extension activity. Six cadaveric knees were tested in the normal state and after implantation of three different single femoral radius TKR designs: cruciate retaining, posterior stabilised and rotating platform posterior stabilised (Stryker, Newbury, UK). QFs in the TKRs were between 15% and 20% lower than normal between 60° and 70° flexion. The increase in PTMA was insufficient to explain the reduced QF in the TKRs. The patellar flexion angle (PFA) of the TKRs was lower than normal at knee flexion angles greater than 50°, probably as a result of the recessed trochlea. A simple patellar model demonstrated that the reduced PFA may explain a large proportion of the reduction in QF after single radius TKR.

Meniscal repair in anterior cruciate ligament reconstruction: a long-term outcome study.

PURPOSE: To study the long-term outcome of patients who have undergone inside-out, vertical stacked mattress suture repair of meniscal tears combined with anterior cruciate ligament (ACL) reconstruction. METHODS: From a database of ACL reconstructed patients, consecutive patients undergoing concomitant meniscal repair and ACL reconstruction between 1991 and 1999 were identified. Patients with previous ACL or meniscal pathology were excluded. Two age- and sex-matched cohorts who had undergone combined ACL reconstruction and menisectomy and who had undergone ACL reconstruction with normal menisci were identified for comparison. Outcome scoring included IKDC and Lysholm scores for the meniscal repair group. Two sample t-tests and chi-square tests were used to compare the IKDC subjective scores, with a minimum level of significance set at 5% (P = 0.05). RESULTS: Fourty-four patients were identified for analysis with a median follow-up of 10 years (7.7-12.6). Patients undergoing ACL reconstruction combined with meniscal repair had a mean IKDC of 84.2 compared with a mean score of 70.5 (P = 0.008) in patients who had undergone menisectomy and 88.2 (P = 0.005) in patients with intact menisci. 86.2% of patients with ACL reconstruction and meniscal repair had Lysholm score of between 80 and 100%. Sixty-nine percent follow-up was achieved. Survival analysis by life table method shows a best case of 89% 10-years survival. CONCLUSIONS: This study demonstrates that good long-term outcomes can be obtained in patients up to over 12 years after combined ACL reconstruction and meniscal repair. Improved functional scores can be achieved when compared with ACL reconstruction and menisectomy. The authors advocate repair of meniscal tears during ACL reconstruction unless there is complex tearing, radial tearing or plastic deformation of the remaining meniscus. LEVEL OF EVIDENCE: III.

A phase I study of extended dosing with lomeguatrib with temozolomide in patients with advanced melanoma.

Lomeguatrib, an O(6)-methylguanine-DNA methyltransferase inactivator, was evaluated in an extended dosing regimen with temozolomide, designed according to pharmacodynamic data from previous studies. Patients with unresectable stage 3 or 4 cutaneous or unknown primary melanoma metastases were treated with lomeguatrib 40 mg, b.i.d. for 10 or 14 days and temozolomide 75-100 mg m(-2) on days 1-5. Drugs were administered orally with cycles repeated every 28 days, for up to six cycles. A total of 32 patients were recruited to the study. Lomeguatrib for 10 days with temozolomide 75 mg m(-2) was established as the optimal extended lomeguatrib dosing schedule, with haematological toxicity being dose limiting. There were two partial responses to treatment giving an overall response rate of 6.25%. Extending lomeguatrib administration beyond that of temozolomide requires a reduced dose of the latter agent. Only limited clinical activity was seen, suggesting no advantage for this regimen over conventional temozolomide administration in the treatment of melanoma.

How effective are added constraints in improving TKR kinematics?

Newer designs of total knee arthroplasty (TKA), through the use of added degrees of constraint, attempt to provide a "guided motion" to restore more normal and predictable kinematics. Two such design philosophies are the posterior stabilised (PS) using a cam-post and the medial pivot (MP) concepts. Knee kinematics of 12 patients with a PS TKA, 13 subjects with a MP TKA and 10 normal subjects were compared. For kinematic assessment, patients underwent fluoroscopic assessment of the knee during a step-up exercise and deep knee bend. Fluoroscopic images were corrected for distortion and assessed using 3D model fitting to determine relative 3D motion, and a 2D method to measure the patellar tendon angle (PTA) as function of knee flexion. For the PS design the cam-post mechanism engaged between 70 degrees and 100 degrees flexion. Between extension and 50 degrees there was forward motion of the contact points. Beyond 60 degrees both condyles rolled moved posteriorly. The majority of the external rotation of the femur occurred between 50 degrees and 80 degrees . The PTA was lower than normal in extension and higher than normal in flexion. The MP exhibited no anterior movement throughout the rage of motion. The medial condyle moved minimally. The lateral contact point moved posteriorly from extension to flexion. The femur rotated externally throughout the range of flexion analysed. The PTA was similar to normal from extension to mid flexion and then higher than normal beyond to high flexion. The PS design fails to fully restrain paradoxical anterior movement and although the cam engages, it does not contribute significantly to overall rollback. The MP knee does not show significant anterior movement, the medial pivot concept appears to achieve near normal kinematics from extension to 50 degrees of knee flexion. However, the results show that at high flexion this design does not achieve normal knee kinematics.

Smoking and reconstruction of the anterior cruciate ligament.

We sought to determine whether smoking affected the outcome of reconstruction of the anterior cruciate ligament. We analysed the results of 66 smokers (group 1 with a mean follow-up of 5.67 years (1.1 to 12.7)) and 238 non-smokers (group 2 with a mean follow-up of 6.61 years (1.2 to 11.5)), who were statistically similar in age, gender, graft type, fixation and associated meniscal and chondral pathology. The assessment was performed using the International Knee Documentation Committee form and serial cruciometer readings. Poor outcomes were reported in group 1 for the mean subjective International Knee Documentation Committee score (p < 0.001), the frequency (p = 0.005) and intensity (p = 0.005) of pain, a side-to-side difference in knee laxity (p = 0.001) and the use of a four-strand hamstring graft (p = 0.015). Patients in group 1 were also less likely to return to their original level of pre-injury sport (p = 0.003) and had an overall worse final 7 International Knee Documentation Committee grade score (p = 0.007). Despite the well-known negative effects of smoking on tissue healing, the association with an inferior outcome after reconstruction of the anterior cruciate ligament has not previously been described and should be included in the pre-operative counselling of patients undergoing the procedure.

Combined anterior cruciate reconstruction and Oxford unicompartmental knee arthroplasty.

The options for treatment of the young active patient with isolated symptomatic osteoarthritis of the medial compartment and pre-existing deficiency of the anterior cruciate ligament are limited. The potential longevity of the implant and levels of activity of the patient may preclude total knee replacement, and tibial osteotomy and unicompartmental knee arthroplasty are unreliable because of the ligamentous instability. Unicompartmental knee arthroplasties tend to fail because of wear or tibial loosening resulting from eccentric loading. Therefore, we combined reconstruction of the anterior cruciate ligament with unicompartmental arthroplasty of the knee in 15 patients (ACLR group), and matched them with 15 patients who had undergone Oxford unicompartmental knee arthroplasty with an intact anterior cruciate ligament (ACLI group). The clinical and radiological data at a minimum of 2.5 years were compared for both groups. The groups were well matched for age, gender and length of follow-up and had no significant differences in their pre-operative scores. At the last follow-up, the mean outcome scores for both the ACLR and ACLI groups were high (Oxford knee scores of 46 (37 to 48) and 43 (38 to 46), respectively, objective Knee Society scores of 99 (95 to 100) and 94 (82 to 100), and functional Knee Society scores of 96 and 96 (both 85 to 100). One patient in the ACLR group needed revision to a total knee replacement because of infection. No patient in either group had radiological evidence of component loosening. The radiological study showed no difference in the pattern of tibial loading between the groups. The short-term clinical results of combined anterior cruciate ligament reconstruction and unicompartmental knee arthroplasty are excellent. The previous shortcomings of unicompartmental knee arthroplasty in the presence of deficiency of the anterior cruciate ligament appear to have been addressed with the combined procedure. This operation seems to be a viable treatment option for young active patients with symptomatic arthritis of the medial compartment, in whom the anterior cruciate ligament has been ruptured.

Influence of surface geometry and the cam-post mechanism on the kinematics of total knee replacement.

Abnormal sagittal kinematics after total knee replacement (TKR) can adversely affect functional outcome. Two important determinants of knee kinematics are component geometry and the presence or absence of a posterior-stabilising mechanism (cam-post). We investigated the influence of these variables by comparing the kinematics of a TKR with a polyradial femur with a single radius design, both with and without a cam-post mechanism. We assessed 55 patients, subdivided into four groups, who had undergone a TKR one year earlier by using an established fluoroscopy protocol in order to examine their kinematics in vivo. The kinematic profile was obtained by measuring the patellar tendon angle through the functional knee flexion range (0 degrees to 90 degrees ) and the results compared with 14 normal knees. All designs of TKR had abnormal sagittal kinematics compared with the normal knee. There was a significant (p < 0.05) difference between those of the two TKRs near to full extension. The presence of the cam-post mechanism did not influence the kinematics for either TKR design. These differences suggest that surface geometry is a stronger determinant of kinematics than the presence or absence of a cam-post mechanism for these two designs. This may be because the cam-post mechanism is ineffective.

Tensile strength of the medial patellofemoral ligament before and after repair or reconstruction.

The tensile strength of the medial patellofemoral ligament (MPFL), and of surgical procedures which reconstitute it, are unknown. Ten fresh cadaver knees were prepared by isolating the patella, leaving only the MPFL as its attachment to the medial femoral condyle. The MPFL was either repaired by using a Kessler suture or reconstructed using either bone anchors or one of two tendon grafting techniques. The tensile strength and the displacement to peak force of the MPFL were then measured using an Instron materials-testing machine. The MPFL was found to have a mean tensile strength of 208 N (SD 90) at 26 mm (SD 7) of displacement. The strengths of the other techniques were: sutures alone, 37 N (SD 27); bone anchors plus sutures, 142 N (SD 39); blind-tunnel tendon graft, 126 N (SD 21); and through-tunnel tendon graft, 195 N (SD 66). The last was not significantly weaker than the MPFL itself.

When is a meniscal cyst not a meniscal cyst?

Two patients are presented where lesions adjacent to the joint line of the knee were diagnosed clinically and on magnetic resonance imaging (MRI) as meniscal cysts. No concomitant meniscal tears were seen, and the MRI signal was not completely homogenous. The diagnostic imaging influenced the surgical management in a manner inappropriate for the definitive diagnoses of fibromyxoid sarcoma and monophasic synovial sarcoma. Not all cysts produce a purely homogenous signal on MRI due to haemorrhage or high protein content fluid, and not all meniscal cysts are associated with a meniscal tear. In the absence of a meniscal tear and with mixed signal on MRI we advise caution in the diagnosis of a meniscal cyst and advocate shared management with either orthopaedic or radiological colleagues with a special interest in oncology to obtain a tissue diagnosis before definitive treatment.

Anatomy and biomechanics of the medial patellofemoral ligament.

The medial patellofemoral ligament (MPFL) is a band of retinacular tissue connecting the femoral medial epicondyle to the medial edge of the patella. The MPFL is approximately 55 mm long, and its width has been reported to range from 3 to 30 mm. The MPFL is overlaid by the distal part of vastus medialis obliquus to a variable extent, and fibres of MPFL merge into the deep aspect of the muscle. Despite the MPFL being very thin, it had a mean tensile strength of 208 N, and has been reported to be the primary passive restraint to patellar lateral displacement. Lateral patellar displacement tests in vitro showed that the patella subluxed most easily at 20 degrees knee flexion. The contribution of the MPFL to resisting patellar lateral subluxation was greatest in the extended knee. This finding was linked to the retinaculae being tightest in full knee extension, and slackening with flexion.

The effect of screw length and position on fixation of four-stranded hamstring grafts for anterior cruciate ligament reconstruction.

The aim of this study was to examine interference screw fixation of four strand hamstring grafts for anterior cruciate ligament reconstruction in vitro. Bovine tibiae and cannon tendons were used. Screws were introduced from 'outside-in'. The tendons were loaded cyclically to 150 N to simulate walking and 450 N to simulate jogging. Slippage of the tendon from the anchorage was recorded after 100, 300 and 1000 cycles. Cortico-cancellous and cancellous only fixations were compared using a 7-mm screw in an 8-mm tunnel with a 7-mm graft. The effect of screw length was studied by comparing 8 x 25 and 8 x 45 mm screws. Graft slippage with cancellous only fixation was significantly greater than with cortico-cancellous screw fixation (P0.105), the longer screws gave more consistent behaviour. We concluded that the screw should be placed so that its head engages the cortex, while increasing screw length within cancellous bone did not significantly improve graft fixation. Cyclical load testing reflects the repetitive forces imposed in the early post-operative period following hamstring anterior cruciate ligament reconstruction and is important for the evaluation of graft fixations.

A comparison of bone remodelling around hydroxyapatite-coated, porous-coated and grit-blasted hip replacements retrieved at post-mortem.

We investigated the implant-bone interface around one design of femoral stem, proximally coated with either a plasma-sprayed porous coating (plain porous) or a hydroxyapatite porous coating (porous HA), or which had been grit-blasted (Interlok). Of 165 patients implanted with a Bimetric hip hemiarthroplasty (Biomet, Bridgend, UK) specimens were retrieved from 58 at post-mortem. We estimated ingrowth and attachment of bone to the surface of the implant in 21 of these, eight plain porous, seven porous HA and six Interlok, using image analysis and light morphometric techniques. The amount of HA coating was also quantified. There was significantly more ingrowth (p = 0.012) and attachment of bone (p < 0.05) to the porous HA surface (mean bone ingrowth 29.093 +/- 2.019%; mean bone attachment 37.287 +/- 2.489%) than to the plain porous surface (mean bone ingrowth 21.762 +/- 2.068%; mean bone attachment 18.9411 +/- 1.971%). There was no significant difference in attachment between the plain porous and Interlok surfaces. Bone grew more evenly over the surface of the HA coating whereas on the porous surface, bone ingrowth and attachment occurred more on the distal and medial parts of the coated surface. No significant differences in the volume of HA were found with the passage of time. This study shows that HA coating increases the amount of ingrowth and attachment of bone and leads to a more even distribution of bone over the surface of the implant. This may have implications in reducing stress shielding and limiting osteolysis induced by wear particles.

Taking the advanced knee arthroscopic surgery course to Singapore.

The Advanced Knee Arthroscopic Surgery course was first organised in 1995 under the joint auspices of the British Association for Surgery of the Knee and The Royal College of Surgeons of England. This is a two-day course in advanced knee arthroscopic techniques, with lectures, videos and extensive practical sessions. The approach is very much hands-on, using cadavers together with sawbones and model knees. Use is also made of the specimens in the Anatomical Museum of the College. Instruction is given in anterior cruciate ligament reconstruction, meniscal repair and posterior cruciate with posterolateral ligament reconstruction. Since 1995 the course has been held on seven occasions and has been attended by over 100 senior trainees and consultants.

A prospective trial of local versus general anaesthesia for arthroscopic surgery of the knee.

We set out to determine if arthroscopic knee surgery was acceptable to patients and their surgeon when carried out using a local anaesthetic infiltration technique. Patients awaiting arthroscopy were randomly allocated to have either a local or a general anaesthetic. The same surgeon (NPT) carried out all the procedures. The demographic profile was similar in the two groups, as were the diagnosis and the surgical procedures. The only difference between the two groups was that those performed under local anaesthesia did not have a limb tourniquet inflated. The time spent in the theatre suite was similar in each group. This did not include the recovery time in the general anaesthetic group. The duration of the operation was longer in the local anaesthetic group (P = 0.05). A simple 0 to 10 scoring system indicated that patients preferred a local anaesthetic but the surgeon preferred to have the patient asleep (P > 0.05). Those having a local anaesthetic required less physiotherapy (P = 0.025) and more of them returned to work and sport earlier (P = 0.05). We attributed this to not having sustained pressure-induced tissue damage to the thigh muscle as they did not have a tourniquet inflated. We had a 4% failure rate in the local anaesthetic group. Arthroscopic surgery is already a well-established day case procedure and our findings have a financial implication (a saving of 25 pounds per case) as well as identifying a safer technique in the medically unfit. Unfortunately, this technique is not suitable for the investigation and treatment of all knee problems. There are certain constraints, viz the very anxious patient, acute problems, children, larger arthroscopic procedures and the inability to perform an examination under anaesthetic but, overall, it is a useful and effective way of performing a common surgical procedure.