ORIGINAL ARTICLE

Medial patello-femoral ligament reconstruction for the treatment of chronic patellar instability : A systematic review of recent evidenc

Akash Patel*, Amarjit Anand**, Abbas Rashid***, Wai Weng Yoon***

* Barnet General Hospital, Wellhouse Lane, London, U.K. EN5 3DJ
**Co-author Watford General Hospital, London, UK
*** Co-author Northwick Park Hospital, London, UK
****Co-author Royal London Hospital, London, UK

Address for Correspondence:

Hospital Address: Barnet General Hospital, Wellhouse Lane, London, U.K. EN5 3DJ
Home Address: 16 Warren Road, Neasden, London NW2 7LH
Phone: 07930556922
Email: akash1981patel@yahoo.co.uk

Abstract:

Aim: The purpose of this systematic review was to identify and critically appraise recently published evidence describing surgical techniques and outcomes of medial patellofemoral ligament reconstruction for patients with chronic patellofemoral instability.

Background: There has been growing awareness of the biomechanical contribution of the medial patellofemoral ligament (MPFL) and its role in chronic patellofemoral instability over the past decade. This had lead to a recent increase in the publication of studies assessing reconstructive techniques and outcomes of MPFL reconstruction. The most recent major reviews were published in 2008, since then a substantial amount of advanced clinical research has been undertaken.

Methods: A PubMed, EMBASE, CINAHL and Cochrane database literature search using the terms “medial patellofemoral ligament” OR “MPFL” AND “reconstruction” was undertaken. Only papers published from 2008 onwards were included. The search was limited to English language articles and humans only. Case reports, anatomical/biomechanical studies and MPFL repair studies were excluded. The primary outcome assessed was post-operative patella dislocation or subluxation. Secondary outcomes included complications and functional knee scoring systems. The critical appraisal checklist (adapted from Critical Appraisal Skills Programme) for an article on treatment was used to guide assessment of the studies identified

Results: Seven eligible studies were critically appraised. All studies demonstrated favourable clinical outcomes following MPFL reconstruction. The post-operative incidence of patellar dislocation and subluxation was minimal in all studies. There was considerable improvement in all functional knee scores. Notable complications included flexion deficits, prominent screws and patellar fracture. A number of methodological weaknesses were identified during critical appraisal of the studies. These included small sample sizes, limited follow-up, varying MPFL reconstruction techniques and confounding adjunctive surgical procedures.

Conclusion: Despite methodological weaknesses in the studies identified, MPFL reconstruction seems to be a promising surgical option in alleviating chronic patellofemoral instability. Further studies comparing MPFL reconstruction techniques and graft types are recommended to address these methodological flaws.

J.Orthopaedics 2011;8(4)e5

Keywords:

Medialpatellofemoral ligament; MPFL; patellofemoral instability; patella dislocation

Introduction:

Chronic patellofemoral instability can be an extremely disabling condition1. The incidence of patellar dislocation is 5.8 to 77.8 in 100,000 2, 3. There have been a number of clinical studies describing the components of the knee extensor mechanism which are important in patellar stability4, 5, 6, 7, 8, 9, 10, 11. Lateral instability is a result of anatomical abnormalities and insufficient soft tissue restraints and is difficult to treat12. The medial patello-femoral ligament (MPFL) has been recognised as being an important stabiliser of the patella, preventing lateral dislocation5, 13, 14  . Studies have shown that the MPFL may contribute up to 80% of the medial passive resistance to lateral dislocation of the patella 6, 7, 10, 15.

Risk factors for recurrent instability can be determined in the clinical history16, 17. Female adolescents are the most common first-time dislocators. Risk factors include a family history, generalised ligamentous laxity, increased valgus angulation and knee hyperextension1. Examination of the knee should include apprehension test, observation for J sign and patella tilt/glide assessment. Many imaging modalities have been described to investigate the patellofemoral joint18, 19. These include plain radiographs (AP, lateral and skyline), CT and MRI scans. Various conservative and surgical options are available for the treatment of chronic patellar instability, including MPFL reconstruction. Conservative treatment options include analgesia, physiotherapy and taping. Before surgery is undertaken, consideration should be given to anatomical and physiological factors1.

These include:

• trochlea and patella morphology
• bony alignment and rotational profile – Q angle, tibial tubercle to trochlear groove offset (TT-TG)
• static soft tissue constraints – MPFL, ligamentum patellae, lateral fascial system, patellomeniscal ligament
• dynamic soft tissue constraints - VMO

Below are tables summarising some of the surgical procedures that may be performed for chronic patellofemoral instability:
Table 1: procedures for patellofemoral instability

Adapted from: Mulford J, Wakeley C, Eldridge J. Assessment and management of chronic patellofemoral instability. J Bone Joint Surg (Br) 2007; 89-B: 709-16.

Table 2: anatomical/ physiological abnormalities in patellofemoral instability and surgical options

Adapted from: Mulford J, Wakeley C, Eldridge J. Assessment and management of chronic patellofemoral instability. J Bone Joint Surg (Br) 2007; 89-B: 709-16.

Recently, there has been increasing interest in the MPFL because of its role in patellofemoral instability. Virtually all patella dislocations cause some degree of macroscopic MPFL damage13 and anatomic studies suggest that lateral patella dislocation is almost impossible without damage to the MPFL20. The MPFL originates at the posterior aspect of the medial femoral epicondyle and inserts along the superomedial patella and into the deep aspect of VMO21. It usually ruptures at its femoral origin upon lateral patella dislocation. Studies have reported 94% of patients suffer MPFL rupture after acute patella dislocations14. Chronic instability seems to be the main indication for MPFL reconstruction16. Some studies have shown no benefit of surgical management for primary patellar dislocation22, 23, 24. As demonstrated by previous reviews, MPFL reconstruction techniques have been promising in the treatment of chronic patellofemoral instability12, 25, 26, 27. Various reconstruction procedures using adductor magnus, quadriceps tendon, semitendinosus, gracilis, and synthetic tissue have been described, however, there is no conclusive evidence that one modality is superior to another12. More than 100 other surgical techniques have been described for treating chronic patellofemoral instability12, 28, 29 since 191530. This indicates that there is no general consensus regarding the surgical management of chronic patellar instability.

Recently, further trials have been published evaluating MPFL reconstruction, therefore this review is warranted to further interpret the body of evidence. The purpose of this review is to critically appraise the recent evidence for reconstruction of the MPFL in the treatment of chronic patellofemoral instability. The focus of this review will be on studies of patients who have undergone MPFL reconstruction for chronic patellar instability. Rates of postoperative patella dislocation or subluxation will be considered primary outcome measures. Secondary outcomes, such as functional knee scores and complications, shall also be discussed. The hypothesis of this review is that MPFL reconstruction may be a promising surgical option in alleviating chronic patellofemoral instability.

Methods

Numerous reviews for MPFL reconstruction for the treatment of chronic patellar instability have been published12, 25, 26, 27. The most recent reviews were published early in 200812, 26. The aim of this review was to appraise the recent clinical evidence assessing MPFL reconstruction. Participants in the studies included were patients with symptomatic chronic patellofemoral instability defined by two or more dislocations. The intervention was MPFL reconstruction. The primary outcomes assessed were rates of postoperative dislocations and subluxations. Secondary outcomes were functional scores and complications. 

A PubMed search for “medial patellofemoral ligament” or “MPFL” and “reconstruction” was conducted in March 2010 which identified a total of 127 articles. Specific search criteria included “English language articles” and “human” species. 112 articles were found. Studies from January 2008 to March 2010 specifically were included. 33 papers were identified within the time period and were limited to 30 following removal of duplicates. Each of the 30 abstracts were thoroughly screened using our exclusion / inclusion criteria specified in Figure 1. Of these, only 7 clinical papers evaluated patient outcomes and were relevant to MPFL reconstruction for chronic patellar instability. A similar search of EMBASE, CINAHL and the Cochrane database did not identify any additional papers. The excluded papers were:

• biomechanical studies (2)
• anatomical studies (3)
• MPFL repair (1)
• case reports (5)
• not directly related to MPFL surgery (2)
• acute patella dislocation (1)
• general reviews of the MPFL or patellar instability (4)
• only novel surgical technique discussion without any patient outcomes (5)

Figure 1: Flow diagram illustrating literature search and selection procedure
Search terms : “MPFL” OR “medial patellofemoral ligament” AND “reconstruction
 
Total number of articles (n = 127)
 
Humans, English, January 2008 – March 2010 inclusive (n = 33)
 
Duplicates removed (n = 30)
 
30 abstracts screened
 

The study by Watanbe et al33 compared MPFL reconstruction using a gracilis or semitendinosus tendon with tibial tubercle transfer (TTT) to reconstruction without TTT. Before 1997, they performed TTT as the main surgical treatment for chronic instability. During a transitional period between 1997 and 1998, they applied both MPFL reconstruction and TTT. Since 2001, they rarely performed TTT even for patients with severe patellofemoral alignment. Patients included in this study had operations between 1993 and 2003. 3 surgeons undertook the surgery, which may have affected the outcomes as each surgeon may have had different levels of experience and skill. The patients undergoing MPFL reconstruction with TTT were on the surgeons learning curves for MPFL surgery, therefore this may have affected the longterm results. Patients undergoing MPFL reconstruction only had operations after 1998, therefore the surgeons were more experienced at this stage. TTT+MPFL surgery was undertaken as either a 1 stage or 2 stage procedure. If TTT alone was unsuccessful in treating persistant instability, MPFL reconstruction was undertaken as a second stage procedure. This was the case for 5 knees. This may indicate that the patients in the 2 stage group have a worse, more complicated degree of instability, therefore this should have been clarified further in the study. Selection bias was not clearly discussed in this paper.

Even though the authors adopted different methods as first choice procedure during different periods, the indication for surgery and patient baseline characteristics for MPFL reconstruction and TTT were similar overall. The authors do state the patient backgrounds were not exactly the same. However age, sex, time from injury to surgery, number of pre-op dislocations, Q angle and follow-up period were similar to allow for comparison of clinical results. A relatively clear, defined research question incorporating participants, interventions, comparator and outcomes was addressed in this study. Forty patients (42 knees) with recurrent patellar dislocation were included. Lateral release was performed for any patient with lateral retinacular tightness or patellar tilt ≥20˚. More knees in the MPFL+TTT group underwent lateral release (12 out of 13 knees) compared to the MPFL only group (6 out of 29 knees). Also, different techniques were used for lateral release. Both of these issues may have affected the outcome. Even though, the baseline characteristics of the patients may have been similar, the fact that more patients underwent lateral release in the MPFL+TTT group may indicate some anatomical difference compared to patients in the MPFL only group.
The authors of this study used appropriate, validated scoring systems (Lysholm, visual analog) to demonstrate their results. However, observer blindind was not clearly described. At the average follow-up of 4.3 years, the Lysholm scores improved from 70 to 92 and 72 to 90 in the MPFL (29 knees) and the MPFL + TTT (13 knees) groups, respectively. There were no losses to follow-up. A visual analog scale demonstrating subjective knee function was significantly higher in the MPFL group (91 vs 81). Appropriate statistical analysis was performed and presented in this study, however no power calculation was undertaken. None of the patients in this study had postop dislocations or subluxations. However, 15% (2 out of 13 knees) in the TT+MPFL group had significant flexion limitation postop. No patients had this complication in the MPFL group. This study demonstrates that MPFL reconstruction alone may yield at least equally good results in patients with recurrent patellar dislocation.

Christiansen et al34 undertook MPFL reconstruction with gracilis autograft alone (n=32) or in combination with TTT (n=12) in patients with recurrent patellar instability and trochlear dysplasia (or increased Q angle), respectively. The research question in this study was defined and addressed participants, interventions and outcomes appropriately. However, the baseline characteristics of patients was significantly different as 18 patients had 1 previous patellar procedure and 8 patients had 2 previous procedures. The study does not adequately discuss the previous procedures in-depth with respect to MPFL reconstruction. Selection bias is not adequately addressed. The study also states that MPFL reconstruction and TTT was undertaken for patients with trochlear dysplasia and chronic patellofemoral instability. There is a clear difference in the patient groups (i.e. trochlear dysplasia).

The results for both groups were combined and presented despite the fact that two separate procedures were undertaken, i.e. MPFL reconstruction only vs MPFL reconstruction and TTT. The group of patients in this study was clearly heterogenous with respect to degree of patellofemoral dysplasia and previous surgeries. However, this heterogeneity gives an indication of clinical results with MPFL reconstruction in the typical chronic patellar instability population.

This prospective case series had an adequate sample size, as ascertained by applying the 1:10 rule for number of variables. Limitations with all case series are lack of defined comparator. This was the case with this study, despite the fact there were two separate groups. Follow up was only for an average of 22 months (range 12 to 32) with no losses to follow-up. This study is limited by investigating the short-term clinical results after MPFL reconstruction.
Postoperatively, 1 dislocation and 3 subluxations were observed. It is not stated which group the patients were in as the results for both procedures were combined. This study used validated subjective Kujala and objective Tegner activity outcome scores. Overall, combined Kujala scores improved from 46 to 84 postoperatively. The Kujala score postop was 88 in the MPFL group and 83 in the MPFL+TTT group when the results were broken down. Postoperative Tegner score was 4 points overall. No statistical power calculation was undertaken and observer blinding was not clearly described in this study.  Postoperative problems occurred with:

• reduced flexion (1 patient had MUA)
• inflammation around interference screws (3 patients had screw removal)
• patella fracture (1 patient had open reduction and internal fixation) caused by misplaced drill holes

The relatively high dislocation/subluxation rate in this group, compared to other MPFL reconstruction studies, may be due to the method of distal fixation. This places undue stress on the medial patellar edge. The authors concluded MPFL reconstruction with double transverse patellar drill holes and gracilis tendon graft provides good postoperative patellar stability.

The non-randomized comparative trial by Sillanpaa et al35 assessed retrospectively selected patients with chronic patellofemoral instability. Comparison of adductor tendon tenodesis MPFL reconstruction (n=18) with distal patellar realignment by the Roux-Goldthwait procedure (n=29) was undertaken. Non-randomization is a limitation as this indicates confounders have not been controlled. The patients underwent operation dependent upon the surgeons preference, indicating significant selection bias. Two surgeons separately performed each procedure. This may have influenced the outcomes as they may have had different levels of skill and experience.

The research question for this study was well defined in the introduction and addressed participants, intervention, comparator and outcomes adequately. The sample size was appropriate, as determined by the 1:10 rule for number of variables. The baseline characteristics for the patients included in the trial were simply defined in terms of age, previous dislocations, previous surgery, followup and arthrosis on plain radiographs. This may be interpreted as a strength of the study as the patient group was relatively homogenous, all being young, healthy male adults. This allowed good comparability between groups. On the other hand, only males were included in this study as patients were recruited from the Central Military Hospital in Finland. Therefore, this sample is not truly representative of the population of patients who suffer from chronic patellofemoral instability. Patients who did not want to undergo surgery for chronic patellofemoral instability were excluded from this retrospective review. Some of these factors may have affected overall long term results. Selection bias was not adequately discussed in this study. Another possible limitation was lack of a nonoperative control group, which may have produced additional evidence regarding the potential benefits of MPFL reconstruction.

Patients were followed for an average of 10.1 years after initial surgery. This long follow-up period is one of the strengths of this study. 3 out of the 18 patients in the MPFL group were lost to follow-up. 8 out of the 29 patients in the Roux-Goldthwait group were lost to follow up. This indicates a significant loss to follow-up which may have affected the results. 1 redislocation was observed in the adductor tenodesis (MPFL) group and 3 occurred in the Roux-Goldthwait group. There were 2 painful subluxations in each group. Observers were not blinded during data collection. The authors themselves conducted a clinical examination and systematic interview which may have introduced bias into the results. Kujala scores were 88 for the MPFL group and 86 for the Roux-Goldthwait group. Tegner activity scores were 4 and 5, respectively. No preoperative scores were calculated due to the nature of patient selection and follow-up. Preop scores would have been useful for comparison. Appropriate statistical analysis were conducted and showed no significant difference in the outcomes for each group. However, no statistical power calculation was undertaken. There was significantly more osteoarthritis in the Roux-Goldthwait group as determined radiologically by the International Cartilage and Repair Society criteria. This study demonstrates a very slight advantage of MPFL reconstruction over distal realignment in long-term results in the treatment of chronic patellofemoral instability.

Gomes et al36 undertook MPFL reconstruction with half width semitendinosus graft in 12 patients with chronic patellofemoral instability. The research question was not clearly defined, however the study did address participants, interventions and outcomes. This case series was limited by the lack of comparator. Clear exclusion and inclusion criteria were defined in this study. However, there was no discussion of baseline characteristics of the patients included or selection bias. There were no comments on follow-up, mean age and sex of patients. The sample size was extremely small, this may compromise statistical validity of results. No statistical power calculation was undertaken. No postoperative dislocations or subluxations were noted. This limited prospective case-series used a subjective functional outcome score (scale of activities of daily living) to quantify results without any discussion of observer blinding. This increased from 40 to 75 postoperatively. No complications were observed. This study concludes that MPFL reconstruction using the half width tendon technique preserves muscle continuity, with faster postop recovery, less complications and effective treatment of instability.

Two MPFL reconstruction techniques were compared in the study by Gomes37. Two matched-pair groups of 12 patients each were selected for either adductor magnus rigid or semitendinosus dynamic femoral fixation. Lateral release was also performed as part of the adductor procedure. To compare the two MPFL reconstruction techniques more accurately, lateral release should have been performed in the semitendinosus group as well. There was no clear explanation in this study as to why lateral release was performed in the adductor group only.

The research question in this study was well defined and discussed participants, intervention, comparator and outcomes adequately. The sample size was small. There were not enough patients for variables according to the 1:10 rule for number of variables. Baseline characteristics for patients were adequately defined and matched for each group. Clear inclusion and exclusion criteria were discussed and applied. Importantly, patients with previous surgery for patellofemoral instability were excluded. However, selection bias was not clearly discussed. The type of surgery was chosen by lot randomisation for the first patient and alternated for the first patient in subsequent pairs. This was not a truly randomised study.

Patients were followed up for an average of 53 months, with no losses to follow-up. 1 of the patients in the adductor magnus group suffered subluxation, none in the semitendinosus group. A subjective functional score (scale of activities of daily living) showed no significant difference between the groups, 72.8 vs. 72.7 respectively. The scores were significantly better than preop, 50.1 and 50.6 respectively. Observer blinding was not clearly described in this trial. Appropriate statistical analysis were undertaken, however no power calculation was performed. No major complication was observed in either group. Patients in the semitendinosus group felt subjectively better, and larger number of patients in this group resumed the practice of sport (8 vs. 4). This study demonstrated some of the biomechanical complexities of MPFL reconstruction and suggested a more dynamic femoral fixation is more advantageous than a rigid alternative.

The prospective case series undertaken by Rongo et al38 assessed MPFL reconstruction using a hamstring graft in patients with recurrent patellar dislocation. The clear research question, well defined eligibility criteria and prospective nature of the trial are strengths of this study. Only patients with a minimum 2.5 year follow-up, 3 or more unilateral dislocations with at least 3 months physiotherapy following each, and undertaking sports at least at recreational level were included. Patients with predisposing anatomical factors and those requiring other surgery (ACL, PCL, meniscal) were excluded. Only including patients who regularly participate in sports may reduce external validity of the results and generalisability of the conclusions of this study, as these patients may be more motivated and different from the general population of patients suffering from chronic patellar instability. Patients with higher levels of motivation will probably have better outcomes. On the other hand, limiting the inclusion criteria may also reduce confounding factors due to the similar baseline characteristics of the sample.

The surgical intervention was extremely well defined. All patients underwent MPFL reconstruction using 2 transverse patella drill holes and hamstring graft. This was a single surgeon series, which
eliminates confounding factors that may be present if multiple surgeons undertook the procedure on the patients included. Post-operatively rehabilitation was standardized, with patients initially partial weight bearing for 2 weeks and starting full sporting activities at 6 months. Primary and secondary outcome measures were not clearly defined in the methods, but included the postoperative dislocations/subluxations, Cincinnati score, Kujala score, anthropometry, radiographic measures and complications. Statistical analyses were appropriate in this study, however no power calculations were undertaken. The number of patients in the study was also small.

Twenty eight patients were included in this study with a mean age of the patients was 32 years (19 – 40) and average of 6.3 (3 – 14) previous patella dislocations. Two patients had previous proximal soft tissue alignment surgery and 1 had previous distal soft tissue realignment. Mean follow-up was 3.1 years (2.5 – 4), which is strength of this study. The mean modified Cincinnati score increased from 52 preoperatively to 89 (P = 0.001). The mean Kujala scores increased from 45 preoperatively to 83 (P = 0.03). There was significantly reduced muscle volume and strength in the operated leg compared with the non-operated leg, but this improved with time. Four patients were lost to follow-up and no intention to treat analysis was performed. Three patients had postoperative dislocations and no patients experienced postoperative subluxations. Complications included knee hypoaesthesia (1 patient), anterior knee pain (4 patients) and reduced flexion (2 patients). At final follow-up, ten patients had grade III/IV patellofemoral osteoarthritic changes.

The authors conclude MPFL reconstruction using hamstring tendon graft passed through a double patellar bony technique is a safe, reliable management option for recurrent patellar dislocation in patients without any predisposing anatomic factors. Overall, interpretation of the study by the authors is consistent with the results with some reservations regarding the methodology.

The retrospective case-series undertaken by Dopirak et al39 assessed MPFL reconstruction using partial thickness quadriceps tendon graft for recurrent patellar dislocation. There was no mention of eligbility criteria for participants at all. This increases external validity of the results as all patients undergoing MPFL reconstruction using quadriceps tendon graft were included. However, this also increases the effects of confounding factors due to variability in baseline patient characteristics. The authors also have poorly defined, unclear criteria for patients eligible for MPFL reconstruction. The intervention, in terms of surgical technique, was clearly explained and was undertaken by a single surgeon. Sutures were used to fix the graft to the medial epicondyle through bone. Postoperative rehabilitation was standardized, with patients weight bearing as tolerated. Outcome measures were extremely well defined. Primary outcomes were postoperative dislocations and subluxations. Secondary outcomes included patient satisfaction, Kujala scores, Crosby and Insall scores and complications.

The authors state that 13 patients (14 knees) underwent the procedure and only 9 were available for follow up. This loss to follow up, lack of intention to treat analyses, lack of power calculation and small sample size are significant weaknesses of this study. Another issue is that of the 9 patients available for follow-up, 5 had previous knee surgery for varying problems. Also, of the 9 patients available, 7 had adjunctive surgical procedures in addition to MPFL reconstruction to treat their chronic patellar instability. These procedures may act as significant confounders. The mean age of patients at surgery was 26.1 years (15 – 40) and mean follow up 3.5 years (2.3 – 5.4).

Postoperatively, no patients had dislocations and only 1 had an episode of subluxation. According to the criteria of Insall and Crosby, 44% of patients had excellent outcomes and 56% of patients had good outcomes. No outcomes were classified as fair to poor or worse. The mean postoperative Kujala score was 91.9 (77 – 100). Postoperatively, all patients reported their knee was improved. With regards to complications, 1 patient developed a wound infection, which required an incision and drainage in theatre, and 1 patient developed a superficial haematoma. The authors conclude that MPFL reconstruction with a quadriceps tendon graft is effective in preventing patellar dislocation and improving quality of life. Due to the poorly defined patient eligibility criteria, significant confounding surgical procedures and poor methodological quality, this study has limited overall external validity. However, even though these factors mitigate any conclusions drawn from the data, the study is still useful due to the novel, well described surgical technique.

Discussion

The aim of this review was to determine whether MPFL reconstruction is an appropriate procedure for chronic patellar instability and critically appraise the recent evidence. Following an extensive literature search, 7 studies were deemed appropriate for reviewed. In summary, 176 patients (179 knees) in total underwent MPFL reconstruction for chronic patellofemoral instability in the studies discussed. Postoperatively, only 5 patients (knees) had patella dislocations and 7 had subluxations. All outcome scores showed improvement following MPFL reconstruction. Time to full weightbearing post-surgery varied from immediate to 2 weeks. Complications included flexion deficit, interference screw problems and patellar fracture. Critical appraisal of these studies demonstrated that MPFL reconstruction provided favourable clinical outcomes for patients with chronic patellar instability.
However, following critical appraisal, a number of methodological deficiencies and were indentified. These included:

• small sample sizes
• limited follow-up period
• poorly defined baseline characteristics of subjects
• no controlling for confounding factors e.g. varying confounding adjunctive surgical procedures
• no power calculation to determine sample size / probability of Type II error
• no observer blinding or randomization in comparative studies

A number of issues may have impacted on the findings of this review. One factor was the variation in the literature regarding the grafts used and addition of other surgical procedures to MPFL reconstruction. This was considered during the literature search phase of the review, but excluding papers that presented other procedures combined with MPFL reconstruction, would have reduced the data available for this review. External validity may have also been reduced as clinical practice would not have been reflected. However, despite this, the addition of adjunctive patellofemoral correction procedures constitutes an incorrigible confounder. This undermines any insights into the efficacy of MPFL reconstruction that these studies might otherwise have offered.

The small sample sizes in some studies may indicate a reporting bias, selection bias, or both. The varying follow-up might indicate a significant amount of “missing” events and complications occurring after the follow-up period. In general, the methodological case series design of some of the studies seemed appropriate, as changes in outcomes could be captured following the procedure.

No paper specified which conservative treatments were undertaken and how long they were trialled for, which is a limitation in the presentation of these papers. However, all studies did clearly document post-operative rehabilitation.
There are other factors which may have affected the findings of this systematic review. Firstly, the selection criteria excluded case reports, editorials, comments, letters, guidelines, protocols, abstracts, and unpublished studies. Although this was undertaken to ensure the studies included were of appropriate high quality and had been through a peer-reviewed process, it may also have introduced publication bias. Secondly, the search strategy was based on a computer search process. Studies7 have demonstrated that computer searches may omit some articles, and consequently, limit the scope of this review. Thirdly, non-English language articles were excluded. This was due to the difficulties with translation. Nonetheless, it may have reduced the breadth of literature review.

Conclusion

Critical appraisal of recent literature suggests MPFL reconstruction may provide favourable outcomes for patients with chronic patellofemoral instability. However, a number of methodological limitations were found in the studies reviewed.  Conclusions made from these papers should, therefore, be interpreted with caution. The studies were relatively small, heterogenous, and employed adjunctive techniques. No clear demonstration of the superiority of any particular MPFL reconstruction technique was shown. However, MPFL reconstruction approaches seem to offer a promising surgical treatment for chronic instability. Further research is warranted to explore MPFL reconstruction and to demonstrate the relative efficacy of different reconstruction techniques, with particular attention to the methodologic quality of future trials.

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This is a peer reviewed paper 

Please cite as :Akash Patel,Medical patello-femoral ligament reconstruction for the treatment of chronic patellar instability : A systematic review of recent evidenc.

J.Orthopaedics 2011;8(4)e5

URL: http://www.jortho.org/2011/8/4/e5